ELECTROTYPING
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ELECTROTYPING
A PRACTICAL TREATISE ON THE ART OF ELEC- TROTYPING BY THE LATEST KNOWN METHODS.
CONTAINING HISTORICAL REVIEW OF THE SUBJECT, FULL DESCRIPTION OF THE TOOLS AND MACHINERY REQUIRED, AND COMPLETE INSTRUCTIONS FOR OPERATING AN ELECTRO- TYPING PLANT.
BY C. S. PARTRIDGE.
SECOND EDITION.
CHICAGO:
The Inland Printer Company.
1908.
Copyright, 1899, Copyright, 1908,
By The Inland Printer Company, Chicago.
PRESS OF THE HENRY O. SHEPARD COMPANY.
PREFACE TO FIRST EDITION.
THE art of electrotyping has within recent years made material advancement. Labor-saving machinery and appliances have simpHfied and at the same time insured greater accuracy in the mechanical features of the art, while the constant and increasing demand for rapid work has been an incentive to invention and research, with the result that electrotypes are now pro- duced in much less time than was formerly required. That the literature of electrotyping, although of great value, is hardly up to date, is evidenced by the state- ments of Urquhart, Wilson, Langbein and others, to the effect that from seven to twenty hours are required to deposit shells of practical thickness. While these state- ments were, perhaps, correct at the time they were pub- lished, they can hardly be considered accurate now, in view of the fact that the plate from which this page is printed was deposited in fifteen minutes.
In the following pages, revised from a series of arti- cles in The Inlm%d Printer, I have endeavored to describe, as clearly and simply as possible, the most approved methods of producing electrotypes, with the hope that the information may prove of value both to the professional and the amateur,
C. S. PARTRIDGE. Chicago, June, 1899.
PREFACE TO SECOND EDITION.
THE general favor accorded "Electrotyping-" made several printings of the first edition necessary. This second edition has been revised and corrected to date and much new matter added, an important addition being a glossary or reference list of terms, processes and apparatus.
C. S. PARTRIDGE.
Chicago, December, 1908.
*♦
CONTENTS
CHAPTER PAGE
I. Historical Review . . ... 7
II. The Battery 18
III. The Dynamo 25
IV. The Bath . . . . ' . . 35 V. Steel, Brass and Nickel Baths ... 41
VI. Management of Baths 46
VII. Agitation of Baths 51
VIII. Measuring Instruments .... 58
IX. Preparation of Work .... 63
X. MoLniNG . '67
XI. Building ' . . . . . . . .78
XII. Metallizing 83
XIII. The Conductors 94
XIV. Depositing 99
XV. Casting 105
XVI. Finishing 119
XVII. Trimming and Routing 127
XVIII. Revising 136
XIX. Blocking 143
XX. Dr. Albert's Metal Molds . . . 150
Reference List of Terms, Processes and Appa- ratus 161
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ELECTROTYPING.
CHAPTER I.
HISTORICAL REVIEW.
DURING the period of 1837- 1839, Professor Jacobi, of St. Petersburg, Mr. Thomas Spencer, of Liver- pool, and Mr. C. J. Jordan, of London, made at differ- ent times announcement of their independent discovery of the art of electrotyping. According to one author- ity the rival claims of Professor Jacobi and Mr. Spencer were presented by them in person before the Chemical Section of the British Association for the promotion of Science, and this august assembly after prolonged dis- cussion decided that both had independently arrived at the same result, but that the priority of discovery was undoubtedly Mr. Spencer's. However, this decision of the society with the high-sounding title did not by any means settle the controversy, which became still further complicated by the later claims of Mr. Jordan, In view of the conflicting character of the evidence we are inclined to divide the honor between the gentlemen named; but whatever merit may attach to their respec- tive claims as discoverers, there is probably no question but that the credit for the first practical application of the new art to the printing business belongs to an Amer-
8 ELECTROTYPING.
ican — Mr. J. A. Adams, of New York, who produced successful electrotypes of wood engravings in 1841. It is to American inxentive genius, also, that we are in- debted for most of the labor-saving methods and machin- ery which have brought the art to its present state of perfection. In England, electrotyping seems to have been first utilized chiefly for the production of metallic art work such as engraved medals, statuary, etc. Messrs. Elkington & Co. were so successful in this branch of the art that in 1845 they had established a considerable business in the duplication of cups, vases and other articles, deposited entirely in gold, silver and copper. While our friends over the water have perhaps excelled in this feature of electrotyping, Americans were quick to grasp and develop the possibilities of the art as applied to printing purposes. In 1863, Mr. William Filmer, an electrotyper of New York, who had much to do with the early development of electrotyping, after an extended trip abroad stated that electrotyping as applied to the printing industry was generally recognized in Europe as an American art.
The discovery of electrotyping, like many other important discoveries, was purely accidental. Mr. Spencer, for instance, was trying some experiments in electro-chemistry. He had immersed a copper plate in a solution of sulphate of copper and a zinc plate in a solution of common salt, connecting them together by a wire, and separating the fluids by a partition of plaster of paris. In order that no action should take place on the wire connecting the plates, he covered it with sealing wax, and in so doing, spilled some of the wax on the copper plate. After a few days he found
ELECTROTYPING. 9
that copper crystals had covered the copper electrode except the portion protected by the drops of wax. It at once occurred to him that by the application of wax or other non-conducting substance, he could perfectly control the deposition of the metal. Mr. Spencer then coated a plate of copper with beeswax, and scratched his name through the wax on the plate and connected it with a zinc plate of corresponding size, immersing them in the solutions as before. After a few hours he found, as he expected, that the portion of the plate from which the wax had been removed was coated with bright metal, while the protected portions remained untouched.
The discovery of electrotyping created hardly less interest than the nearly contemporaneous invention of the electric telegraph. Scientists, professional men and workmen became alike interested, and the copying of medals, coins, etc., by electrotyping becarne a popular amusement of the time.
The apparatus employed at this time consisted of a single cell, as before described. The back of the coin or medal to be copied was first coated with wax or var- nish. Copper was then deposited on its face to form a matrix, which, after having been removed from the coin and properly prepared, was returned to the bath to receive in its turn a deposit of copper in the form of a facsimile of the original.
In 1840, Mr. Joseph Murray discovered that non- conductive substances could be made conductive by applying to them a film of graphite. This was a nota- ble step in the progress of the art, for it not only made possible the duplication of nonmetallic objects, but opened the way for the use of gutta-percha, wax and
10 ELECTROTYPING.
similar substances for molding material in which an impression of the coin or other object could be made, thereby greatly expediting the work by saving the lime required to make a matrix in copper.
The invention of the separate battery about the same time, by Mr. Mason, marked another material advancement in the art.
Mr. Adams made his first electrotype copies of wood engravings by depositing copper directly on the engraving and using the deposit for a matrix. The process was, of course, very crude and invariably destroyed the wood engraving, but it was of value as an insurance against checking and because the electro- type would stand much more wear than the wood cut.
Mr. J. W. Wilcox, of Boston, Massachusetts, an employee of Mr. Daniel Davis, was the originator of the methods by which electro^yping was made of prac- tical use for the printing business. Mr. Davis had produced a few electrotypes, but after the method laid down by European experimenters ; and it may be that Mr. Wilcox obtained, through his connection with Mr. Davis, his first information of the possibility of making duplicates by galvanoplasty, yet Mr. Davis did not encourage, but, on the contrary, endeavored to dis- suade Mr. Wilcox from the notion that something, in a business way, could be gotten out of the new art. Mr. Wilcox had so much faith in a successful result that he resigned his position, that of foreman for Mr. Davis, engaged a room and devoted his energies to the work. In less than one month thereafter he produced electrotypes from cuts and type, without injury to the originals, by virtually the same manipulation that is
ELECTROTYPING. 11
now used. His most important discovery was of a wax composition in which molds could be readily made by pressure. He immediately started in the business of making plates for printers' use, and was the first to make a business of electrotyping. He showed speci- mens of electrotypes in the fifth exhibition of the Mas- sachusetts Charitable Mechanic Association (1847), and page 42 of the report for that year reads as follows :
2. J. W. Wilcox, Boston. Specimens of Electrotype. These specimens are produced, as we think, in a manner original with Mr. Wilcox. The originality, consists in making the matrix, upon which the copper is deposited, of wax, either coated or mingled with plumbago. Previously, matrices were usually made of soft metal upon which, in a melted state, the original plate was laid and subjected to a smart blow, when the melted metal was partially hardened in the process of cooling. Objections to this mode are: liability of injuring molds or plates made of soft materials and, of course, its inapplicability to wood engravings, and the diffi- culty of obtaining perfect matrices, since even a small por- tion of air beneath the plate might, when the blow is given, materially injure the cast. Besides, the old mode is hardly practicable, when the plate is of great extent. By the method of Mr. Wilcox, matrices of any dimensions can be made from a plate or mold of any materials without the least injury to the original ; and the liability of failing to obtain a good matrix is almost wholly obviated.
We hence infer that, among other benefits resulting from this process, it will be found more economical, and will con- tribute much to the beauty and perfection of the impression, to use copper plates made from the blocks for wood engra- vings, than to use the blocks themselves. Indeed, several of the specimens exhibited were of this kind, and impressions from them substantiate the opinion of the committee.
One of the specimens examined was a copper stereotype
12 ELECTROTYPING.
plate for common printing, accompanied by an impression from the plate. This suggests to the committee what they consider the most important feature of the subject, namely, the probability that copper stereotype plates will take the place of common type-metal plates. The circumstances to warrant this probability are, the greater durability of copper plates and the more perfect outline of the letters. That copper plates will be more durable does not admit of a doubt ; and some practical men express their belief that they will last six times as long as type-metal plates. If so, and if, as is almost certain, copper is soon to become much cheaper than at present, there will be a decided economy in using copper plates, and the use of them will contribute very materially to the diffusion of knowledge, and, as we trust, to the growth of virtue. In addition to this, the impression from such a plate will be much more distinct and beautiful, inasmuch as a mold in wax will have its lines better defined than a similar mold in plaster. — Gold Medal.
Mr. Davis had an exhibit of magnetical apparatus in the same class and year, for which he was awarded a gold medal, and it is not likely that the award to Mr. Wilcox would have passed unchallenged if not prop- erly made.
Mr. Wilcox continued in business many years to his profit, but did not derive as much financial benefit from his inventions as he might had he patented them. He died in West Roxbury, Massachusetts, February 19, 1876.
The following, from a letter recently received from Mrs. Wilcox in reply to an inquiry regarding her hus- band, shows that Mr. Wilcox did not confine his efforts entirely to making printers' plates :
He perfected the art so well that the Massachusetts Charitable Mechanic Association, in 1847, awarded him a gold medal for specimen of electrotypes. The American
ELECTROTYPING. 13
Institute of New York awarded him a medal in 1848. He turned his attention to making clock dials and steam-gauge dials and all kinds of ornamental plates for decorating soda fountains and other ornamental work. He invented a proc- ess of electrotyping the face of rolls for dressing cloth, and received a medal in i860 from the Massachusetts Charitable Mechanic Association for the same.
Mr. Daniel Davis — properly Daniel Davis, Jr. — was a prominent manufacturer of philosophical instru- ments, in Boston. In 1842 he published " Davis' Man- ual of Magnetism," in which the process of electro- metallurgy was mentioned, and there appeared a cut and an electrotype duplicate of the same. In the sixth edition, published in 1847, there is a frontispiece — two pages — one of which was printed from an origi- nal engraving, on copper, and the other from an elec- trotype duplicate made by depositing on the original for a matrix, and by depositing on the matrix to make the plate printed from. At the bottom of the page it is stated that that duplicate was made by Mr. Davis. Page 53 of that edition was printed from an electro- type made by Mr. Wilcox. The seventh edition of Davis' Manual, issued in 1848, contains the following regarding the electrotype process :
An engraved copper plate may be copied by taking an impression on clean and bright sheet lead with a powerful press, or if the plate is small it may be pressed by hand on the melted fusible metal. Or a mold may be made by depos- iting copper on the plate itself, but care must be taken to prevent adhesion both of the mold to the original and of the copy to the mold. The duplicate thus obtained will furnish engravings which can not be distinguished from those printed from the original plate, however elaborate the design and delicate the workmanship may be.
14 ELECTROTYPING.
An engraving printed from an electrotype plate by this method is given as a frontispiece to the 1842 manual.
A medal or engraved plate is placed in the solution and copper deposited upon it. The negative wire of the battery should be connected with the rim of the medal, and in case of an engraved plate it may be soldered to the corners. The deposit is apt to adhere very firmly, sometimes so much so that its removal is impossible. This may be avoided by slightly greasing or oiling the mold and then brushing it over with a little dry copper bronze.
The mold thus obtained may have a wire soldered to it and be placed in the solution like the original one. In most cases it will be considered safer to take a mold of a valuable medal or plate in soft wax or by some of the other processes to be described. An engraving printed from an electrotype plate obtained by this process is given as a specimen in the 1847 manual.
In the same edition there is the following notice:
This book is believed to be the first ever electro-stereo- typed throughout. A single page (the 53d) of " Davis' Man- ual of Magnetism," published in August, 1847, was previously electrotyped by the subscriber in the same manner. The advantages of this process are : First, its durability, the copper face of the type and illustrations lasting many times longer than the type-metal; and second, the blackness of the impression taken from copper.
I am prepared to execute any orders for printed work in the above style, of which the present book is an example, and to execute any number of facsimiles of engraved copper plates and of whatever size. The face of each electrotype copy is harder and more durable than the rolled copper.
I am also prepared to execute plates of electrotype copper for engraving of greater purity and uniformity than can otherwise be prepared.
I have, within two years, electrotyped a large number of wood cuts, many of which have been in constant use and
ELECTROTYPING, 15
which have answered every expectation as to their durability and the perfect character of the impression.^
The report of the Massachusetts Charitable Mechanic Association, taking the lowest estimate, assigns to these a durability six times greater than that of the type-metal stereo- types. The slight additional expense of the electro-stereo- types is therefore in no proportion to their comparative value.
Ornamental work and every branch of the art of electro- typing will receive the attention of the subscriber.
J. W. Wilcox.
In 1853, an improvement in the Smee battery was suggested by Mr. Adams, and immediately adopted by electrotypers in America and Europe. Other improve- ments of a more or less important nature were made by Mr. Adams, Mr. Wilcox, Mr. Filmer and others, and by 1858-59 the electrotyping business may be said to have become established on a practical basis ; so much so that the process was quite generally employed for the reproduction of wood cuts.
In the meantime electricians had been busy with the problem of producing a continuous current of elec- tricity by mechanical means which could be substi- tuted for the battery. Machines more or less useful for this purpose were constructed by Dr. W. Siemens, of Berlin, in 1857. Between i860 and 1870, Gramme, Schuckert, Weston, Brush, and Wilde, brought out improvements of more or less value. The Wilde machines were the first to be used to any extent for electrotyping, and were first adopted, about 1872, by Frank Leslie and Lovejoy, Son & Co., of New York City. They accomplished a revolution in the art by reducing the time required to deposit a shell to about three hours. Invaluable as these first machines were
16 ELECTROTYPING.
to the electrotyping trade, they soon gave place to improved types, until at the present time it is possible to produce an electrotype shell thick enough for ordi- nary purposes in one hour or less.
Improvements in molding, blackleading and finish- ing machinery have kept pace with the advancing methods of electrotyping proper. In 1855, Mr. J. A. Adams invented a blackleading machine with a vibrat- ing brush and traveling carriage. In 1856, Mr. Filmer patented a method of backing electrotype shells, by means of which the shell was held down by springs during the operation of casting. In 1858, Mr. S. P. Knight invented an improvement in the preparation of electrotype molds for the bath which was of great value to the trade and is universally employed at the present time. His invention consisted in precipitating a thin film of copper on the mold previous to immers- ing it in the bath. This is accomplished by flooding the mold with a solution of sulphate of copper and then dusting iron filings over it. The effect of the operation is to cause the deposition of copper to begin immedi- ately over the entire surface, instead of beginning only at the points of contact and spreading slowly there- from to other portions of the mold. Mr. Knight also invented, in 1871, a process for applying blacklead to the molds in the form of a solution, distributing it over the face of the mold by means of a traveling rose nozzle.
Many other improvements of a minor nature, which we have not space to describe, have been made from time to time, and the art of electrotyping may be said to be now in a high state of perfection.
ELECTROTYPING. 17
In 1857, Alfred Smee made the remark that " elec- trotyping is likely to be useful for the Bible, Shakes- peare, ' Pilgrim's Progress,' or works that have a large circulation." But the world has made wonderful prog- ress in forty years, and the art of electrotyping has kept up with the procession. Improved methods, labor- saving machinery, cheapening material and the skill which comes from long experience have combined to reduce the cost and improve the quality of the product, and to-day electrotyping has become an indispensable auxiliary to the printing business. It is perhaps safe to say that seventy-five per cent of the books published during the last decade have been electrotyped, to say nothing of innumerable engravings and jobs of all kinds which have passed through the electrotypers' hands. Fifty years ago there were in existence per- haps a dozen electrotyping plants. There are in the United States alone about two hundred and fifty estab- lishments having an estimated annual output of over $5,oOo,ooo. To such proportions has grown a business that had its beginning a half a century ago in a quart jar.
18 ELECTROTYPING.
CHAPTER II.
THE BATTERY.
ELECTROTYPING as applied to the manufacture of printing plates may be briefly described as follows : A mold of the object to be copied is taken in beeswax and suspended, together with a plate of copper, in an acidulated solution of copper sulphate. The mold is attached to the negative pole of a battery or dynamo and the copper plate to the positive pole. The electric current passing through the bath decomposes the solu- tion and sets the copper free on the wax mold, deposit- ing it in an unbroken sheet. When the copper shell has become of sufficient thickness it is removed from the mold, strengthened with a backing of soft metal, straightened, shaved, trimmed and blocked, and is then ready for the printing press. As thus described the process is apparently a simple one ; but it is, in fact, an art which demands a high degree of manipulative skill and the closest attention to detail.
The electric current which makes the electrotype possible must be of a certain strength and tension. If too strong or too weak, the deposited copper would be brittle, crystalline or spongy, and unsuitable for electro- types. It is obvious, therefore, that the source of elec- tricity is a most important consideration. The dynamo is now so generally employed for electrotyping that a detailed description of the galvanic battery would seem
ELECTROTYPING. 19
to be out of place were it not for the fact that there are possible conditions under which the battery may still be found useful — such, for instance, as small experimental work, the deposition of copper during the night, or under other circumstances where power for operating the dynamo is not available.
In discussing the galvanic battery no effort will be made to consider the theory either of its action or the effect of the current on the solution. It will be suffi- cient to consider simply those facts a knowledge of which is essential to the successful practice of electro- typing. A plate of zinc and a plate of silver immersed in acidulated water and connected together with a wire will generate a current of electricity, and if this current is passed through a copper sulphate solution under proper conditions the solution will be decomposed. Why this is so and how it is done are matters concern- ing which various theories have been published in books devoted to these subjects and to which the reader is respectfully referred.
While a scientific education is not essential to the successful practice of the electrotyper's art, he should possess a sufficient knowledge of chemistry and of the principles of electro-metallurgy to enable him to prop- erly prepare and care for his solutions and to recognize the cause and apply the remedy for the difficulties which will occasionally confront him. It is essential, also, that the student of this subject shall become familiar with certain technical terms which are unavoidable in a dis- cussion of the subject. The following list will be found to contain most of the words and terms peculiar to electrotyping :
20 ELECTROTYPING.
Positive plate, the active element (zinc) of the bat- tery. Negative plate, the inactive (silver) element of the battery. Positive pole, the wire attached to the silver plate by which the current leaves the battery. Negative pole, the wire attached to the zinc plate by which the current returns to the battery. Electrodes, the immersed surfaces of metal or other conductor, by which the current enters and leaves the liquid. Anode, the pole or plate by which the current enters the solu- tion. Cathode, the wax mold or other surface receiving the deposit and by which the current leaves the solu- tion. Volt, the unit of electro-motive force. Ampere, the unit of current strength. Watt, a current of one ampere at the pressure of one volt.
There is hardly any limit to the number and variety of galvanic batteries extant, but for various reasons the one invented by Mr. Alfred Smee and bearing his name has been found most suitable for electrotyping. When a plate of copper and a plate of zinc are immersed in acidulated water and connected together with a wire, a current of electricity will at once begin to circulate, starting at the zinc, or positive plate ; passing through the fluid to the copper, or negative plate, and thence through the connecting wire back to the zinc. The current thus generated is at first powerful, but gradu- ally decreases in strength and finally ceases altogether, owing partly to so-called local action in the zinc plate and partly to the adherence of hydrogen bubbles to the copper plate, which have the effect of insulating it. The local action referred to is caused by particles of other metals, such as lead and tin, which are nearly always present in zinc to a greater or less extent.
ELECTROTYPING. 21
These foreign metals form minute but independent bat- teries in themselves, which serve to rapidly dissolve the zinc. This local action may be minimized by amalga- mating the zinc plate with mercury, which is done in the following manner : After thorough cleaning with caustic potash or dilute sulphuric acid, the zinc plate is placed in a shallow vessel and every part of its surface carefully coated with mercury mixed with a little sul- phuric acid. The coating may be applied with a flan- nel cloth tied to a stick or in any convenient manner, and should be well rubbed in.
The adherence of hydrogen bubbles to the copper plate may be prevented to a large extent by roughening its surface. Mr. Smee improved upon this plan by sub- stituting a silver plate for the copper plate and roughen- ing the surface of the silver by platinizing. The first cost of silver plates is considerable and platinizing is also an expensive process, but the Smee battery is so far superior to the zinc-copper battery for electrotyping that the difference in first cost is a matter of small con- sequence. Solid silver plates are seldom employed in the battery, heavily plated copper plates having been found to answer the purpose nearly as well. Platinizing is effected by suspending the silver plate in a saturated solution of bichloride of platinum and acidulated water in the proportion of one part solution to thirty parts water. In the same vessel opposite the silver plate is a porous cell containing sulphuric acid and water ( i to id) with a zinc plate suspended in it. On connecting the zinc and silver plates with a wire the platinum in the solution will be deposited on the silver plate in the form of a nearly black powder, which roughens the surface
22 ELECTROTYPING.
of the plate and effectually prevents the adherence of hydrogen bubbles.
A battery may consist of one or more sets of plates, the number and size of plates to be determined by the amount of work to be performed. To produce the best results the surface of the zinc element in the battery should equal the cathode surface in the depositing bath. That is to say, if it is desired to deposit copper on four molds at one time, each one square foot in area, then the battery should contain an equal area of zinc surface; a convenient size for the plates in a battery of this capacity would be 12 by 12 inches. A battery made up of four zinc and two silver plates, each twelve inches square, would deposit a good quality of copper over eight square feet of area.
The electro-motive force of one Smee cell is sufficient to deposit copper on shallow molds, and there is, there- fore, no necessity for employing more than one cell for ordinary electrotyping, but care should be taken to make the cell large enough to accommodate a sufficient num- ber of zinc plates to equal the area of the molds in the depositing bath. In this connection it may be explained that while a strong current may be employed in electro- typing, but very little tension or electro-motive force is required, and it is well to remember that the size of the battery or the number of plates it contains, have noth- ing to do with its electro-motive force or the pushing power of its current. A cell of one quart capacity has the same E. M. F. as one of 100 gallons, but the strength or quantity of current depends on the area of zinc surface attacked. It is, therefore, essential in mak- ing up a battery for electrotyping to connect all the zinc
ELECTROTYPING.
o.q
plates to one electrode, and all the silver plates to the other. As before stated, the E. M. F. of one cell is sufficient for ordinary electrotyping; but for such work as steel or nickel facing, one cell would not have suffi- cient power to overcome the resistance offered by the iron or nickel solutions, and it becomes necessary to couple two or more cells together by connecting the zincs of one cell with the silvers of the other. In this
Fig. I. Electrotype Battery.
way the power of the battery to overcome resistance is increased in proportion to the number of cells employed, but the strength of the current remains the same unless the area of zinc surface attacked should also be increased. In Fig. I is illustrated a single-cell battery showing the electrode and cross-rods for supporting the zinc and silver plates. This cell is i8 inches long, i8 inches deep and i6 inches wide, and is designed for four zinc
24 ELECTROTYPING.
and two silver plates, each 1 2 inches square. This bat- tery is large enough to deposit from eight to ten feet of copper at a time. The electrodes are ^-inch copper rods, and the cross-rods are ^ inch in diameter. The vat is constructed of pine or vvhitewood planks, bolted together, and is lined with asphaltum.
To obtain satisfactory shells at a minimum expense, the battery should receive careful attention. The zinc plates must be kept thoroughly amalgamated to prevent waste. With this object in view the plates should be frequently examined, and when dark spots are observed the plate should be reamalgamated. When not in action the zinc plates should always be removed from the cell. The battery should be stirred as often as every other day to equalize the solution, which becomes dense from the addition of sulphate of zinc. A little acid and water must also be added from time to time to keep up the strength of the battery. In mixing acid and water the acid should always be added to the water, and this should be done very slowly and carefully to avoid sudden heat and consequent danger of explosion. The silver plates require very little attention except an occa- sional washing, but should be platinized two or three times a year if in constant use.
After being in action about a week the battery usually becomes so impregnated with sulphate of zinc that the addition of acid has little or no effect upon it. If the quantity of sulphate becomes excessive, it will crystallize on the positive element and entirely stop the action of the battery. When such conditions appear, it is better to throw away the contents of the battery than to attempt a remedy.
ELECTROTYPING. 25
CHAPTER III.
THE DYNAMO.
AS previously stated, there are certain conditions . under which the galvanic battery may be found useful as a current generator for electrotyping, but it should be understood that in every respect except the quality of copper deposited the battery is inferior to the dynamo. Compared with the machine the battery is both slow and expensive. A shell which would require twelve hours' time to deposit with the battery may be deposited in one hour with the dynamo, and leaving the time element out of consideration the actual cost of deposition by the battery method is probably six times as great as by the machine. Theoretically a pound of copper should be obtained for each pound of zinc and acid consumed in the battery, but in actual working the consumption of zinc amounts to nearly two pounds. With zinc at 7 cents per pound, a copper shell tAd of an inch in thickness would cost for deposition about 3 cents per square foot. On the other hand, a dynamo with a capacity of 160 square feet per day can be opera- ted at an expense for power of not to exceed 75 cents, or about J^ cent per square foot. The current gener- ated by the dynamo is powerful, uniform, and easily managed; while the machine itself requires but little attention, is clean and always ready for business.
Dynamos of various sizes and types are now manu- factured specially for electrotyping and plating purposes.
26
ELECTROTYPING.
and the electrotyper is offered an unlimited assortment from which to choose. Dynamo building is no longer a mystery, and its principles are so well understood that there is no more excuse for building an inferior machine than there would be for building a poor steam engine.
Fig. 2. Electrotvping Dynamo.
There is, therefore, little danger of disappointment if the dynamo is purchased from a reputable manufac- turer, provided the requirements of the machine are thoroughly understood by purchaser and seller. It would be folly to attempt to force a ten-horse engine to do work requiring twenty horse-power, and it is equally
ELECTROTYPING. 27
foolish to expect a dynamo to do more work than it is designed to do. Here is where an error is often made. To save the few dollars difference in first cost a small machine is installed, overloaded and condemned, when the fault is not in the machine but in the man who over- loads it. Competition between builders of dynamos induces them to claim for their respective machines the utmost limit of their capacity when running under the most favorable conditions, and as the conditions are not always favorable, dissatisfaction results. The elec- trotyper should himself have a definite idea of the number of square feet he will require to deposit at one time and the speed at which he wishes to work, for it is true in electrotyping as in mechanics generally that ' ' we cannot get something for nothing. ' ' A dynamo which will deposit loo feet of shells in two hours will deposit only 50 feet in one hour, and if a rapid rate of deposition is desired a correspondingly large machine must be employed.
Authorities differ somewhat in their estimates as to the maximum current density which may be employed in electrotyping ; but it is safe to figure on about twenty- five amperes per square foot with the solution at rest and about fifty amperes with the solution in motion. On this basis, a dynamo of 500 amperes, with an E. M. F. of i)^ volts working one vat, would deposit about twenty feet at a time. If speed were no object a some- what larger area could be covered by reducing the volt- age. The most economical method of utilizing the current, and the one generally employed, is to connect the machine to two vats in series. By this means the current is utilized in both baths before it returns to
28
ELKCTROTVPING.
05
the machine and the capacity of the dynamo is nearly doubled. Fig. 3 is a plan view of a double vat, show- ing the method of con- necting the dynamo in ^ ^^ scries. The current leav- ing the machine traverses the electrode a, enters the solution in the first vat by anode ( i ) , passes through the solution and leaves the vat by cathode (3) and the dead rod c, enters the second vat by the anode (2), leaves it by cathode (4) and returns to the dynamo by elec- trode d. By this method the current is made to do duty in both vats ; but inasmuch as the resist- ance of two solutions is double the resistance of one solution, the E. M. F. of the current must be double what would be re- quired for a single bath. If one volt pressure will overcome the resistance of one solution to an ex- tent sufficient to accom- plish a satisfactory rate of deposition, then two volts will be required to effect the same rate of deposition in two
Fig. 3.
Dynamo Connkctions on Double Vat.
ELECTROTYPING. 29
vats. It should be remembered that within certain Hmits the rate of deposition depends on the strength of current employed, and this fact should have due con- sideration in estimating the capacity of a machine. A good quality of copper may be deposited with a current density of thirteen or fourteen amperes per square foot, but the rate of deposition would be slow. On the other hand, fifty or more amperes per square foot may be em- ployed, under proper conditions, with a corresponding increase in the rate of deposition, but at an additional expense for power. In the first case, roughly speaking, about four hours would be required to deposit a shell TT)*i)5 of an inch in thickness, while in the latter case one hour would be sufiicient to deposit the same weight of copper. In the first case a 500-ampere machine on one vat would deposit about thirty-five feet at one time, while in the latter case it would deposit only one-fourth as large an area, but would accomplish the work four times as fast. In the long run the result would be the same so far as the total quantity of copper deposited is concerned, and where speed is no object the former current density is preferable because more economical in power.
It has been stated that fifty or more amperes per square foot of cathode surface may be utilized in elec- trotyping under proper conditions, and that shells of average weight may be thus deposited in about one hour. To effect such a rapid rate of deposition it is essential, first, that the dynamo shall be constructed to supply a large volume of current without dangerously heating the machine; second, the solution should be properly proportioned; third, the solution or the anodes
30 ELECTROTYPING.
must be kept in constant motion; and fourth, all con- nections must be of large size, and the points of contact clean and firmly made.
Large plants, in which more than two vats are oper- ated, usually employ more than one machine. In other words, it is considered good policy to employ two dyna- mos for four vats, rather than to couple all four vats to one dynamo. The object of such an arrangement is that one-half the plant may be discontinued during a dull season, and it also permits the use of low voltage machines, such as are carried in stock by the manufac- turers. From what has been previously said on this subject, it will be obvious that a dynamo working four vats in series would require to have four times the volt- age needed for one vat, and twice the voltage needed for two vats. If a very rapid rate of deposition is desired, a machine working four vats would need to be operated at a tension of eight or ten volts, whereas a tension of four to five volts would be sufficient for two vats. Machines of the latter capacity are of standard make, while it is probable that a ten-volt dynamo would have to be specially constructed.
When purchasing a dynamo, consideration should be given to the possible maximum output of the foun- dry, as well as the rate of deposition desired. If the plant includes but one molding press and one black- leading machine, and rapid work is not imperative, a dynamo of 450 amperes and two volts would take care of all the work which could be turned out, for such a machine working two vats in series would deposit from forty to fifty square feet at one time, and would deposit a sufficiently heavy shell in about three hours. In other
ELECTROTYPING. 31
words, it would deposit about fifteen feet per hour, which would probably be the limit of the capacity of a foundry of the indicated size. If, however, it is desired to deposit fifteen feet every hour instead of forty-five feet every three hours, a much larger machine would be required, for, as has been before stated, the rate of deposition depends principally on the strength of cur- rent employed; and while a sufficient current density for a limited number of shells could be obtained from the small machine, it could be applied to only one vat at a time, because sufficient E. M. F. could not be generated to force the current through two solutions at the maximum speed. The capacity of the machine in square feet of cathodes which could be deposited at one time would, therefore, be cut down to one-quarter of the surface which could be covered at slow speed.
To further illustrate this point, we will suppose a dynamo of 450 amperes and 2 ^ volts to be connected with two baths in series. Each bath would then be supplied with a current of i ^ volts pressure, and the quantity of current utilized would be approximately 30 amperes per square foot of cathode. The total capacity of the machine, 450 amperes, divided by 30, gives 15, the number of feet which can be deposited at one time in each bath, or a total of 30 feet. Now, if it is desired to double the rate of deposition, it becomes neces- sary to double the pressure of the current, which would mean 5 volts instead of 2^. As the small machine cannot be made to produce 5 volts, the only alternative is to disconnect one of the vats. We now have 2^ volts applied to one bath, and are using about 60 amperes per square foot of cathode ; 450 divided by 60
32" ELECTROTYPING.
gives 7j^ as the maximum number of feet which could be deposited at one time, and this is in theory only, for in actual practice it is found impracticable to deposit more than 5 feet, owing to the tendency of the machine to heat. The economy in operating a large dynamo for rapid deposition is thus plainly evident.
The results of a series of tests recently conducted by the writer are given below :
Dynamo No. i Lloyd
Speed 1.350
Volts 2%
Amperes per square foot, about 51
Number of baths i
Area of cathodes, square feet 7
Time of exposure, minutes 60
Thickness of deposit, inches 003
A similar test of a No. i Eddy dynamo produced the same result. It should be said that during the tests these machines were both operated at higher speeds than those mentioned, with the result that shells .007 of an inch were deposited in one hour; but owing to heat generation only two or three square feet of cathode surface could be exposed at one time.
A test of a larger machine resulted as follows :
Dynamo No. 2 Lloyd
Speed 1,000
Volts, per vat 2^
Amperes per square foot of cathode, about. 54
Number of baths in series 2
Area of cathodes, square feet 20
Time of exposure, minutes 60
Thickness of shell, inches 0035
These tests indicate that a dynamo of 800 amperes and 5 volts, working two baths in series, will deposit,
ELECTROTYPING. 33
without undue heating, about twenty-eight feet of shells per hour ; while a 450-ampere, 2^ -volt dynamo will only deposit about seven feet per hour. It appears, therefore, that rapid deposition is not practicable with a small machine. However, the difference in cost of installation is of slight moment in view of the increased product of the large machine, and should not stand in the way of the better service, particularly as the larger dynamo will perform a limited volume of work equally as well as the smaller, and at only a nominal increase in expense for power. In later tests with larger dynamos and an agitated solution the current strength was increased to 125 amperes per square foot, with the result that practical shells were produced in fifteen minutes. The above mentioned tests are given with the object of indicating how present facilities may be utilized to the best advantage by electrotypers whose machines equal or excel the capacity of the No. 2 Lloyd.
Dynamos, as a rule, require but little attention, but should always be kept clean and well oiled. The com- mutator, in particular, should be occasionally cleaned with a piece of fine sandpaper (not emery paper) and then wiped off with a clean, damp cloth. Slow-speed machines require no lubricant on the commutator other than an occasional wiping with a damp cloth. On high- speed machines a very little vaseline may be applied every two or three hours. The brushes should fit the commutator fairly well, otherwise there will be a ten- dency to spark and heat. Sparking should never be permitted, as it rapidly wears the commutator. It may often be prevented by moving the brushes a little one 3
34 ELECTROTYPING.
way or the other from the position in which the spark- ing occurs.
For nickel-facing electrotypes a current tension of 2^ to 3 volts is required, and for this work a separate dynamo is usually employed ; but when the electrotyp- ing dynamo is sufficiently powerful the nickel bath may be operated in connection with the copper baths by pro- viding it with a resistance coil for regulating the strength of current supplied to it. With a dynamo operating at 2^ volts it would be possible to work the nickel bath without a resistance coil, as in this case a sufficient vari- ation of current strength could be obtained by varying the distance between the cathodes and anodes. But if the tension exceeds 23^ volts, a means must be pro- vided for cutting down the current to the point best suited to the conditions of the work.
ELECTROTYPING. 35
CHAPTER IV.
THE BATH.
THE depositing bath for electro typing in copper con- sists of a solution of blue vitriol acidulated with sulphuric acid. Copper sulphate, blue vitriol, or blue stone, as it is variously termed, forms crystals which when unadulterated are pure blue in color and cannot be mistaken for any other chemical. A green tinge indi- cates the presence of sulphate of iron and should be rejected. While the color is a sufficient guide to the purity of the sulphate it may be further tested by boil- ing a small quantity of the solution with a little nitric acid and adding spirits of ammonia in excess. The presence of iron will be indicated by brown flakes. Distilled water or filtered rain water should, if possible, be used in making the solution. If rain or distilled water cannot be conveniently obtained, well or lake water will answer, but should always be thoroughly boiled and filtered.
Sulphuric acid (oil of vitriol) for acidulating the solution should be used pure and concentrated. The crude acid contains arsenic which renders it unfit for use in electrotyping solutions. The pure acid has a specific gravity of 1.84. It may be recognized by mixing one part with twenty-five parts of distilled water and com- pounding with a few drops of barium chloride, when a white precipitate will be formed. In diluting acid with
36 ELECTROTYPING.
water it should always be added to the water very slowly and with constant stirring, as the heat generated by the contact of the acid and water might otherwise be suffi- cient to cause a dangerous explosion. Sulphuric acid is exceedingly corrosive and should always be kept in glass bottles or carboys.
The copper solution is the least troublesome of all electrolytes. While some baths require accurate pro- portionment, the use of distilled water, and even an exact degree of temperature for their successful opera- tion, the copper bath may be widely varied in propor- tion and will work well under considerable variation ot temperature. Nevertheless, there are certain limits oi proportionment which must be observed to obtain rapid deposition of a good quality of copper; for, while the rate of deposition depends very largely on the strength of current, it is essential that the solution be constituted to work in harmony with the current. The essential qualities of the solution are to present the least possible resistance to the electric current and to dissolve the anode with the same rapidity with which the copper from the solution is deposited on the cathode. A solu- tion of copper sulphate without the addition of acid will conduct electricity, but its resistance is such that a very strong current is required to overcome it. Von Hiibl found that the minimum current density per square foot of cathode in a fifteen-per-cent blue vitriol solution without acidulation is 24. i amperes, while the same solution with six per cent sulphuric acid added required but 13.9 amperes. But while it is thus shown that the addition of sulphuric acid lessens the resistance
ELECTROTYPING, 37
of the solution, there remains a wide difference of opin- ion as to the maximum quantity of acid which may be employed to advantage.
It is not difficult to prepare a solution which with a moderate current will deposit copper of good quality at a moderate speed. As an evidence of this fact it may be stated that it would be difficult to find two solutions exactly similar, the variations extending from twelve to twenty-two per cent blue vitriol, and from two to eight per cent acid. However, there is no question but that a moderately rich solution is preferable and even neces- sary for rapid work. A solution poor in copper will deposit quickly, but the shells are apt to be porous and granular. On the other hand, a solution too rich in copper will deposit slowly and in crystalline form. Deposits of this nature are specially noticeable when a weak current is employed, and it is also noteworthy that a poor solution is much more apt to produce gran- ular deposits when the current is strong. From these facts it appears that a richer solution may be employed with a strong than with a weak current. Almost any kind of a solution, within reasonable limits, will do good work if the current strength is adapted to work in har- mony with it. That is to say, by observing the quality of copper deposited and increasing or decreasing the current strength as the conditions demand. For in- stance, if a pulverulent deposit is obtained it is an indi- cation that the current is too strong or the solution too weak, and the defect may be most easily remedied by reducing the current strength either by means of a switchboard or by decreasing the speed of the dynamo.
38 ELECTROTYPING.
On the other hand, a crystalline, brittle deposit indi- cates a weak current or a rich solution, and may be remedied by increasing the dynamo speed. However, if rapid deposition is desired the solution must be con- stituted to work with a strong current, and defects in the deposit should be remedied, so far as possible, by changing the solution rather than the dynamo, inas- much as a reduction in the speed of the machine would retard the rate of deposition. Of course, there are well-defined limits to the current strength which may be effectively employed with any solution, and it should be the object of the operator to determine the highest effective point of harmony between the two. With the bath at rest, a fourteen to sixteen per cent solution acidulated with two to three per cent sulphuric acid and a current density of fifteen to eighteen amperes per square foot has been found most satisfactory. An agi- tated solution may be made somewhat richer if a stronger current be employed, say eighteen to twenty per cent blue vitriol and three to six per cent acid. The depositing vat for the copper solution should be solidly constructed of pine or whitewood planks bolted together and lined with sheet lead united at the corners by ' ' burning ' ' or melting the sheets together. Solder- ing will not answer, as the acid in the solution will attack the solder, and soon eat its way through. The vat should preferably be partitioned into two compart- ments, in order that the dynamo may be operated in series, as previously described. It is essential also that the vat shall be of ample size. The resistance presented to the electric current by the solution is enormous,
ELECTROTYPING.
39
and only a great area will compensate for its lack of conductivity. At least loo gallons of solution should be provided for each twenty feet of cathode surface exposed. A convenient size and shape of depositing vat is shown in Fig. 4. The length is 60 inches, width
Fig. 4. — Electrotyper's Depositing Vat.
30 inches, and depth 26 inches. It will contain about 200 gallons of solution, and will accommodate about ten cases of average size in each compartment.
In mixing the solution the vat should be about two- thirds filled with rain, distilled or boiled water. The blue vitriol may be conveniently dissolved by suspending it in cheese-cloth bags just under the surface of the water. As the water becomes saturated it will sink to the bottom of the vat, and should be frequently stirred and tested with a Baume hydrometer, when 14 or
40 ELECTROTYPING.
15 degrees is indicated on the instrument the bags of vitriol may be removed and sulphuric acid added to the solution, with constant stirring, until the reading of the hydrometer is increased two or three degrees. This solution will work well with a moderate current. If the current strength is more than 20 amperes per square foot, the solution may be enriched by the addi- tion of blue vitriol to the extent of two or three degrees, and if required as many degrees of acid may also be added.
The solution should be well stirred, and may be used at once, although it usually works better after standing a few days.
ELECTROTYPING. 41
CHAPTER V.
STEEL, BRASS AND NICKEL BATHS.
COPPER is almost universally employed for the pro- duction of electrotypes for printing purposes, and generally speaking it is the most suitable of all metals for this purpose. It is easily deposited, is tough, duc- tile, practically non-corrosive and inexpensive. How- ever, it is too soft to stand the wear of very large edi- tions, and it does not print well with colors containing mercury, which chemically attacks copper. To over- come these defects it is customary, when the circum- stances are such as to warrant the extra labor and expense, to face the copper electrotype with steel, brass or nickel. This is effected (a) by suspending the fin- ished electrotype in the proper solution and depositing thereon a film of harder metal, or {b) by suspending the wax or other mold in the hard-metal solution, obtaining thereon a preliminary deposit, and then trans- ferring it to the copper bath where it is strengthened by a sufficiently heavy deposit of copper. Of these meth- ods, the former is the more readily performed and the latter the more accurate in results. By the former method it is obvious that only a very thin facing can be given to the electrotype without impairing its accu- racy, and it is doubtful if any kind of a facing could be given to a fine-screen half-tone by this method
42 ELECTROTYPING.
without destroying something of its delicacy. How- ever, electrotype plates of ordinary character may have a thin facing of harder metal deposited upon them without perceptibly affecting their accuracy.
Of the three metals employed for facing electrotypes, nickel is the more readily deposited and its solution the least troublesome to manage. It is malleable and duc- tile, and nearly or quite as hard as iron. Moreover, it is non-corrosive and altogether is an ideal metal for the purpose. Various solutions are recommended for the nickel-depositing bath, each of which has its ad- vocates, but many of them are more or less compli- cated and require special care in management. A simple bath which has been thoroughly tested in some of the largest electrotyping establishments in the coun- try is made by dissolving the double sulphate of nickel and ammonia in warm water in the proportion of ^ of a pound of the salts in each gallon of water. The procedure is the same that has been recommended for the copper solution, i. e. , the salts should be sus- pended in cheese-cloth bags just under the surface ot the water until entirely dissolved, when the solution should be well stirred and is then ready for use. Some operators add about ten per cent of common salt to the solution for the purpose of increasing its conduc- tivity.
The deposition of iron is attended with more or less difficulty, and is not always successfully accomplished even by experienced operators. A good bath for iron (steel) facing may be made by dissolving two pounds of the double sulphate of iron and ammonia in each
ELECTROTYPING. 43
gallon of water. Another bath, recommended by Urqu- hart, is prepared by adding a solution of carbonate of ammonia to a solution of sulphate of iron until the iron is precipitated, when the liquid portion should be poured off and the precipitate washed, after which it is dissolved to saturation in a bulk of sulphuric acid equal to the volume of solution required.
Another iron solution consists of 56 pounds of car- bonate of ammonia dissolved in 35 gallons of water and supplied with iron by means of a large anode and an electric current from the dynamo.
The solution which seems to be most popular for the production of iron electrotypes, and which is highly recommended by M. Klein, is composed of equal parts of sulphate of iron (green vitriol) and sulphate of mag- nesia, kept neutral by bags of carbonate of magnesia suspended in the bath. A sufficient quantity of the sulphates should be dissolved in water to make the spe- cific gravity 1.55, i. e. , about 51° Baum6. This bath requires a current density of 18.5 amperes per square foot. A peculiarity of all iron solutions is that the anodes must always be of large size, preferably about eight times as large as the cathodes.
The deposition of brass is also attended with some difficulty, chiefly because it is composed of two metals, one of which is positive and the other negative, hence the current strength requires more or less regulation to insure uniform deposition of both metals. As brass is composed of copper and zinc, the salts of these two metals must necessarily form the basis of the depositing solution. A good brassing solution consists of 16
44 ELECTROTYPING.
ounces of cyanide of potassium, 5 ounces carbonate of copper, i^ ounces carbonate of zinc, i ounce of ammonia, and i gallon of water. The following formu- las are recommended by Roseleur and Dr. Langbein: Copper sulphate and zinc sulphate, each 53^ ounces, and crystallized carbonate of soda, 15^ ounces. Crys- tallized carbonate of soda and crystallized bisulphide of soda, each 7 ounces ; 98 per cent potassium cyanide, 8^ ounces ; arsenious acid, 30^ grains ; water, 10 quarts. The bath is prepared by dissolving the copper and zinc sulphates in 5 quarts of warm water, and in the other 5 quarts, the 15^ ounces of carbonate of soda; then mix both solutions, which will form a pre- cipitate of the carbonates of copper and zinc. After setting ten or twelve hours the supernatant liquor is poured off and sufficient water added to the precipitate to make six quarts of solution. Now add to the bath with constant stirring the carbonate and bisulphide of soda. Dissolve the potassium in 4 quarts of cold water and add this solution to the first solution with the ex- ception of one-half pint, in which the arsenious acid is dissolved by the aid of heat, when it is also added to the bath. This solution should be thoroughly boiled for one or two hours and the water lost by evaporation replaced.
Another brass solution, which is less troublesome to prepare, contains crystallized carbonate of soda, ioj4 ounces ; crystallized bisulphate of soda, 7 ounces ; neutral acetate of copper, 4.4 ounces ; crystallized chloride of zinc, 4.4 ounces ; 98 per cent potassium cyanide, 14. 11 ounces; arsenious acid, 30^ grains;
ELECTROTYPING. 45
water, lo quarts. Dissolve the carbonate and bisul- phate of soda in 4 quarts of water, then mix the acetate of copper and chloride of zinc with 2 quarts of water and add this solution to the first ; retaining, however, a small portion of it in which to dissolve the arsenious acid with the aid of heat. Finally, add the arsenious acid solution, when the bath becomes clear. Boiling the bath or working it through with the current is required.
The following solution is recommended by Watt : Cyanide of potassium, i pound ; carbonate of ammonia, I pound ; cyanide of copper, 2 ounces ; cyanide of zinc, I ounce ; water, i gallon.
Another brassing solution which the writer has found very satisfactory consists of 16 ounces cyanide of potassium, 5 ounces carbonate of copper, i ^ ounces carbonate of zinc, i ounce ammonia, and one gallon of water.
Solutions containing cyanides would immediately destroy wax or gutta-percha molds, and their use is therefore restricted to plating or facing electrotypes or other metallic articles.
46 ELECTROTYPING.
CHAPTER VI.
MANAGEMENT OF BATHS.
THE acid copper solution is not difficult to manage and may be kept for years in constant use by adding from time to time a little of one or the other of its constituents as may be needful to make good the loss occasioned by various causes. This loss is prin- cipally by evaporation, and by simply adding a few pints of distilled water the solution may generally be restored to nearly its original proportions.
Under ordinary conditions the copper withdrawn from the bath and deposited on the cathode is not fully replaced by the anodes, and it is necessary, there- fore, to enrich the solution occasionally with a little sulphate of copper, which may be done by suspending just under the surface of the solution a few pounds of the crystals in a cheese-cloth bag. A reduction in the content of copper in the bath from this cause always produces a corresponding increase of free acid. Should the content of acid become excessive, it may be neu- tralized by the addition to the solution of a little car- bonate of copper.
When the anodes are larger than the cathodes — or when, as may happen, a number of anodes are left in the bath, connected with the current, while molds are
ELECTROTYPING. 47
being prepared for the depositing process — the quan- tity of copper dissolved will exceed the quantity depos- ited, resulting in undue concentration of the solution. This condition will be indicated by a tardy formation of the deposit and the production of a shell of brittle and crystalline character. Moreover, a dense solution, unless continuously agitated, is apt to produce streaky deposits. An excess of copper is further indicated by the formation of crystals of sulphate of copper on the sides of the vat and sometimes on the anodes. When such conditions appear, the obvious remedy is to dilute the solution with water. However, the addition of water to make good the loss caused by evaporation is usually sufficient to remedy any excess of copper without further dilution.
A quiescent solution always becomes more concen- trated at the bottom than at the top of the vat. As a result of this condition the lower portion of the anode will be dissolved less freely than the upper on account of the increased resistance; but, on the other hand, the copper will be deposited more rapidly on the lower por- tion of the cathode where the largest quantity of metal is in solution. For the same reason that portion of the cathode which is suspended in the heavier strata of the bath is apt to become covered with nodules or excres- cences which are more or less annoying and wasteful. This difficulty may be minimized by stirring the solution occasionally with a wooden paddle, which will tem- porarily equalize its density. The bath should not be stirred while in use, particularly if old and dirty, as the
48 ELECTROTYPING.
impurities which will have settled on the bottom of the vat would be likely to lodge on the work and cause holes in the shells. Some electrotypers are content to stir the solutions once a week, usually on Saturday evening, thus giving the bath thirty-six hours in which to settle; but, unless very dirty, it is advisable to stir it as often as every twenty-four hours. When a bath has become so dirty that it cannot be agitated without danger of injuring the work it should be filtered.
The temperature of the bath should be kept between 65 and 75 degrees Fahr. At 65 degrees the best qual- ity of copper is produced; but the quality is not seri- ously impaired by raising the temperature ten degrees, while the rate of deposition is materially increased. Baths located in a room not heated at night may be provided with a coil of lead pipe through which steam may be circulated and the temperature increased thereby as desired. Deposition always proceeds sluggishly on cold mornings, unless some provision for warming the solution is made. It is always desirable to keep the baths in a room separate from the molding and finishing departments in order to protect them as far as possible from dust and flying particles of metal. It is also a good plan to keep the vats covered when not in use.
The anodes should be removed from the solution daily, and thoroughly cleaned from the slime which accumulates on them and which has the eflfect of par- tially insulating them.
What has been said regarding the general care of the copper bath applies also to the nickel bath. An
ELECTROTYPING. 49
occasional addition of water to restore the loss occa- sioned by evaporation is imperative, as is also the addi- tion of a few crystals of nickel salts from time to time if the bath becomes impoverished.
Brass and iron baths are more troublesome than either copper or nickel. The brass bath requires fre- quent building up, particularly if not in regular use. As brass contains a larger proportion of copper than zinc, the copper in the bath becomes first exhausted, and sufficient carbonate or cyanide of copper, according to the constitution of the bath, must be added to restore the proper proportions. Cyanide of potassium must also be supplied when the action of the bath becomes sluggish and no bubbles are observed on the cathodes. When, however, there is a vigorous evolution of gas it is an indication of an excess of cyanide, and a slow deposit under these circumstances would be remedied by the addition of the metallic salts. A deposit of light color would indicate a want of copper in the solution, and a dark color a lack of zinc. However, the color is not a reliable guide, as it may be caused by a variation in the density of current employed. A weak current would deposit more copper than zinc and would give its color to the deposit, while a strong current deposits both metals in their proper proportions. Constant watchfulness is required to keep the brass bath in good working condition.
The iron bath is even more troublesome than brass and less certain in the production of satisfactory depos- its. Owing to its tendency to oxidize, the bath must i
50 ELECTROTYPING.
be frequently filtered to insure uniform deposits. For the same reason it should be kept under cover when possible. The surface of anodes exposed should always be seven or eight times greater than the cathodes.
ELECTROTYPING. 51
CHAPTER VII.
AGITATION OF BATHS.
THE continuous agitation of the copper bath is of great advantage to the electrotyper, particularly when rapid deposition is desired. The copper is more evenly deposited and of better quality, the formation of gas bubbles and also of nodules and excrescences is largely prevented, while the annoying streaks which sometimes appear on the deposit, usually as the result of an excess of metal in the solution, are seldom or never seen in an agitated bath. But the principal advantage may be found in the fact that much higher current densities may be utilized, resulting in a corre- sponding increased rate of deposition. With a quiescent solution the quantity of current which may be employed is limited to about i8 or 20 amperes per square foot ; any excess of this quantity usually results in a deposit, dark red or black in color, and rotten, porous or granu- lar in texture. But in an agitated bath these defects disappear. The copper becomes lighter in color, and tough and ductile in character, and these conditions will not change materially even when the current density is increased to 100 amperes or more per square foot. A quiescent solution is seldom of equal density throughout. The heavier portions settle to the bottom
52 KLFXTROTYPING.
of the vat and the lighter portions rise to the top, and while the density of the bath may be temporarily equal- ized by occasional stirring, there is a continual tendency to separation. The evils resulting from this lack of homogeneity have been described in a previous chapter, and the remedy for these evils is continuous agitation. There are various methods by which this object may be accomplished. A small propeller may be operated near the bottom at one end of the vat, or, where sev- eral vats are employed, they may be arranged in steps and the solution permitted to flow through a connecting pipe from the upper vat to the next lower vat, and so on through the series.
Fig. 5 shows a depositing vat arranged for working by the Englehard process. For electrotyping, the anodes used are about 7 inches wide and i^ inches thick, the length being as may be needed for the work in hand. They are mounted on spindles as shown, and by suitable arrangement are rotated by power while the battery is in action, the usual rate of speed being about fifty revolutions per minute. The agita- tion of the solution insures thorough mixture and uni- form density ; friction between the solution and the moving anode clears its surface of foreign matter and facilitates its rapid dissolution. This also permits the employment of much greater electrical energy than in vats as ordinarily worked — in fact, quite beyond the capacity of nearly every plating dynamo in use. The inventor claims a current of 6 or more volts per vat, and 75 to 100 amperes per square foot of cathode
ELECTROTYPING.
53
Fig. 5.
54
ELFXTROTYPING.
may be used without the least indication of burning the deposit, which is of finer quality than that usually made in the old way, and the quantity of metal thrown down is fully twice as much in a given time.
The Dunton* method for producing a circulation in the solution is illustrated in Fig. 6. A small centrifu- gal pump, with a capacity of about 40 gallons per
Fig 6.
minute, rests on the bottom of one corner of the vat. The solution is drawn in through a strainer at a point over the center of the wheel, near the bottom of the vat, and discharged near the surface. In this manner the heavier liquid is lifted, and by the force of its dis- charge a circular motion is imparted to the whole body. It is forced toward the end of the tub, where it glances
ELECTROTYPING. 55
across, down the other side, some of it passing between the anodes and cathodes, across the opposite end to a point nearly over the pump. The pvmip occupies an area 6^ inches square by 4 inches high, and is con- structed entirely of lead and hard rubber. Above the solution the shaft ends in a length of hardened steel tubing, which runs in the upper bearing and carries the driving gear. The two lower bearings, under the solu- tion, consist of flint glass bushings pressed into hard rubber jackets, then forced into the sleeves provided at the top and bottom of the pump casing.
Fig. 7 illustrates the Leetham apparatus, which is particularly suitable for electrotyping solutions. Agita- tion is effected by air compressed in a reservoir by a small double-acting pump. The air is forced into the baths through perforated lead pipes which lie on the bottom of the vats, where they are entirely out of the way of the work.
The perforations in the pipes are only about one inch apart, which insures thorough circulation of the solu- tion between the anodes and cathodes.
The pressure is regulated by valves, and the agita- tion may therefore be made more or less violent at the pleasure of the operator. On top of the air reservoir and connected with it is a condensing chamber through which the air passes before it is admitted to the vat. The condensing chamber is provided with an inlet for steam. When it is desired to increase the temperature of the bath or increase its contents of water, steam is admitted to the chamber, where it is condensed, and is
56
ELECTROTYPING.
Fig. 7.
ELECTROTYPING, 57
then conveyed to the solution through the air pipes. This device therefore provides a means for heating the sohition and supplying it with distilled water as well as agitating it. Another obvious advantage of this appa- ratus is that one machine will agitate the contents of several vats.
r)S ELECTROTYPING.
CHAPTER VIII.
MEASURING INSTRUMENTS.
A CONVENIENT and almost indispensable measur- ing instrument in the electrotype foundry is the hydrometer, or, as it is popularly termed, acid gauge. By its aid the desired quantity of salts or acid in the bath may be conveniently measured, and the specific gravity of any solution readily determined. The hydrom- eter consists of a glass tube with a graduated stem of uniform diameter, a bulb to cause it to float in the liquid, and a weight to keep it upright as it floats. From the reading of the scale at the point which is on a level with the liquid in which it is floating, the density of the fluid may be ascertained. In pure water at a temperature of 60° Fahr., the hydrometer sinks to the zero mark, but by the addition of salts or acid having a greater density than water, the bulb is forced upward, and the reading on the scale will then indicate the increased density. In making up electrotyping solutions, the hydrometer is floated in a vat partially filled with water. Sulphate of copper is then dissolved in the water until the increased density of the solution forces the instrument upward to a reading which is
ELECTROTYPING. 59
known to indicate the desired proportions. Sulphuric acid is then added to the solution until the desired quantity is denoted on the scale of the instrument. To further illustrate : a popular bath for nickel-plating is made by dissolving three-fourths of a pound of salts in each gallon of water ; but instead of weighing the salts and measuring the water the same proportion may be obtained by dissolving salts in any quantity of water until the hydrometer scale registers 7 degrees. There are two well-known makes of hydrometers in use, namely : the Baum^ and the Twaddle. Every degree on the scale of a Twaddle hydrometer represents .005 of a degree of specific gravity. Zero on the scale is equivalent to i.ooo specific gravity. To ascertain by a Twaddle hydrometer the specific gravity of any liquid heavier than water, multiply the reading by .005 and add 1.000. For example, the reading on the hydrom- eter is 60 degrees : 60 X .005 = .300 + i.ooo = 1.300, the actual specific gravity of the liquid. The specific gravity of a liquid may also be easily ascertained by means of a Baum^ hydrometer by a simple calculation as follows : Subtract the reading from the number 144, and divide the same number by the difference. For
example, 144 — 50 = -^ ^ i-532, the specific gravity
94 of a liquid registering 50 degrees on a Baume hydrom- eter.
Instruments for measuring electric currents should belong to the equipment of every well-ordered electro- typing establishment. In the early days of the art it
fiO ELECTROTYPING.
was sufficient to know that a current of some kind was at work and that in due course of time a shell of suf- ficient thickness would be deposited. It might take twelve hours at one time and eighteen at another, but a few hours more or less was not considered of serious moment. With the modern electrotyper, however, every minute counts, and as a rule he employs all the current strength which can be utilized without burning the deposit. Having learned by experience what quan- tity may be employed to advantage, it is of great con- venience to be able to measure the current and by means of proper registering instruments maintain the pressure at the maximum point. Instruments for meas- uring electricity are the voltmeter and the ammeter. The former measures the tension and the latter the density of the current. While the scientific electrotyper would find both instruments convenient, the ammeter is not indispensable, for the strength of a current proceed- ing from a dynamo increases with the tension, and an instrument which registers the tension would, so far as the electrotyper' s necessities are concerned, also meas- ure the volume. Assuming that one volt pressure is sufficient to force a current of 12 amperes per square foot of cathode through a solution of given proportions, then with two volts pressure the current strength would be increased to 24 amperes and three volts would mean about 36 amperes per square foot. If, therefore, the electrotyper is provided with a voltmeter he may determine with sufficient accuracy for his purpose the strength of current employed.
ELECTROTYPING. 61
The speed with which copper may be deposited depends on certain conditions, but more especially on the density of current employed. To reproduce such conditions at all times it is important that the E. M. F. existing between the anode and cathode should be accurately measured. The ordinary galvanometer is insufficient for this purpose because it does not give an accurate reading of the tension. On the other hand, a sensitive voltmeter will indicate any loss of power due to slipping belts, short circuits or irregularities of any kind, and when used in connection with a switchboard will enable the electrotyper to accurately reproduce the conditions which he has found by experience conducive to success.
The switchboard or resistance board consists of a number of metallic spirals, usually of German silver, arranged on a board in such a manner that one or more of them may be switched into the circuit, thus presenting more or less resistance, as may be desired, to the passage of the current. The utility of the switchboard may be illustrated as follows : sup- pose a tension of 2j^ volts is desired in the bath and that by reason of slipping belts or other causes the tension has been reduced to 2^ volts. Then by moving the handle of the switchboard one or two but- tons a corresponding number of spirals will be cut out of the resistance, permitting a larger quantity of current to enter the bath. Or suppose the load in the bath be much smaller than usual, or for any other cause the ten- sion increases beyond the desired limit, a movement of
62 ELECTROTYPING.
the switch handle ia the opposite direction will increase the resistance by adding to the number of spirals in the circuit and the tension will thus be regulated. The wires connecting the voltmeter with the baths may be arranged in such manner that the tension in any one of a series may be readily determined.
ELECTROTYPING. 63
CHAPTER IX.
PREPARATION OF WORK.
SUCCESS in electrotyping depends largely on care- ful attention to details, not the least important of which is the preparation of cuts or type forms for mold- ing. The finished electrotype must be perfectly flat to insure satisfactory printing. If the original form is defective by reason of imperfect justification, high or low cuts or type, the defects will necessarily appear in the electrotype and must finally be rectified at the finishing bench. The truth of the old adage ' 'A stitch in time saves nine ' ' is nowhere better illustrated than in electro- typing. A few minutes' time spent in making ready the form for molding frequently saves hours at the finishing , bench, particularly when a number of duplicate electro- types are made from the same form. For instance, a broken or mashed type, unless discovered and replaced by a perfect one before the form is molded, will be a defect existing in every electrotype made from that form and must be finally corrected by punching out the defective letter and soldering in its place a perfect type. These defects are not always the fault of the electro- typer, but it is nearly always difficult to convince the
64 ELECTROTYPING.
printer of that fact unless a proof is furnished by the printer with the job.
Printers' forms frequently consist of both type and cuts, and it often happens that the cuts are lower or higher than the type. Here again a few minutes' time spent in shaving down or underlaying the cuts, as the case may demand, will save much valuable time in the later operations of finishing, and will also insure a better electrotype, for it is obvious that if the cut is low in the plate it must be forced up to a level with the type by punching or hammering, and it will be plain, even to the novice, that a plate which has been subjected to such treatment will be less perfect than one which has been corrected in the original and which, therefore, requires but litde attention from the finisher.
Usually better results are obtained by the molder from metal-mounted cuts than when they are mounted on wood, as the wood bases are liable to yield somewhat under pressure and will thus make a shallower impres- sion in the molding composition than the surrounding type. Moreover there is danger of losing something of the detail of the engraving. This is more especially true of half-tone engravings, which should always be mounted on metal bases.
Wood engravings, when subjected to changes of tem- perature or atmospheric conditions, sometimes check or crack. When it is desired to make an electrotype of such an engraving, the checks, if not too large, may be closed by covering them with strips of damp blotting paper and then applying a hot building iron to the
ELECTROTYPING. 65
paper until it is wholly or partially dry. When the check has been closed the mold should be made at once before it has time to open again.
Forms which are to be electrotyped should be sur- rounded by type-high beveled bearers with the beveled side next the type. The bearers prevent the wax or composition from spreading, and also serve to protect the face of the electrotype from injury during the oper- ations of shaving and finishing.
When low leads, quads and furniture are used to justify the form, the larger blanks may be filled up to the shoulders of the type with strips of wax. The wax will adhere to the furniture sufficiently to hold them in place when the form is inverted on the case ; and, on the other hand, if the wax filling is well brushed over with black- lead after it has been placed in the blanks, it will not adhere to the mold. Preparing the forms in this manner will prevent undue displacement of the molding compo- sition and facilitate the later operations of cutting down and building. Parts of book pages or pages of poetry should have an inverted type placed in each corner of the page to indicate the size of the page and serve as a guide to the finisher, and title-pages and large blanks of all kinds should have inverted letters so placed as to protect isolated lines from injury during the finishing processes.
All forms which are to be electrotyped should be
securely locked in extra strong chases and be perfectly
justified. The type should be squarely on its feet and
carefully planed. The pressure employed in molding is
5
66 ELECTROTYPING.
such that unless great care is taken to lock up the forms securely the wax will be forced between the bodies of the type, causing them to spread and throwing them off their feet. This will result in an imperfect plate, and at the same time be the cause of much trouble and annoy- ance owing to the difficulty of removing the wax thus firmly imbedded in the form. Moreover, unless the form is securely locked, there is danger that some of the types will be drawn out of the form, when it is separated from the mold, and lost or misplaced.
ELECTROTYPING. 67
CHAPTER X.
MOLDING.
THE most important department of electrotyping, from the workman's point of view, is the molding, and it is here that the question of profit or loss on a job is often determined. In some other departments of the foundry the work may be slighted to some extent with- out materially affecting the output, but carelessness or inefficiency on the part of the molder always means delay, extra expense for finishing inferior electrotypes, and possibly a final rejection of the job. A cheap (poor) molder is always the most expensive man in the foundry, for unless a perfect mold is obtained the time expended in later operations of depositing, casting and finishing will be wasted. Until recently the mate- rial most generally employed for molding composition was beeswax, mixed with a little crude turpentine and plumbago. The proportions vary somewhat, according to the ideas of the molder. A good combination is composed of pure beeswax eighty-five per cent, tur- pentine ten per cent and plumbago five per cent. If the molding room is very warm, about five per cent of burgundy pitch may be added with advantage. A cheaper material which is now quite generally em- ployed is ozokerite. Ozokerite is a mineral wax, which can hardly be distinguished from beeswax. It has a
68 ELECTROTYPING
high melting point, is non-adhesive and by most elec- trotypers is claimed to be superior to beeswax for gen- eral work. In some instances gutta-percha is employed as a molding material, and under proper conditions the results obtained are very satisfactory. The kind best adapted for the work is what is known as the unmanu- factured but purified sheet. Gutta-percha takes a coat- ing of blacklead readily, and is impervious to the solu- tion. When used for molding without pressure, as is usually the case in duplicating steel engravings or arti- cles of a fragile nature, it is melted and thoroughly mixed with about forty per cent refined lard, or it may be dissolved in bisulphide of carbon, and then moder- ately heated until it is thin enough to pour.
A good molding composition for certain purposes may be made by melting together one pound of lead, ^ pound of tin, and i^^ pounds of bismuth. This alloy melts at the temperature of boiling water, and assumes a soft but firm condition just before setting, at which time the impression should be made. The principal advantage of this composition is found in the fact that it expands in cooling, and therefore takes a very sharp impression. An elastic composition recom- mended by Urquhart, which may be used for molding an entire object at one time, is prepared as follows: Eight pounds of good glue is soaked in cold water until quite soft. It is then placed in a glue-pot and mixed with two pounds of treacle. The whole is heated and thoroughly incorporated by stirring; when the mold is not likely to be roughly handled, ^ pound of beeswax may be added to the mixture. This material is poured around the prepared object, and when set
ELFXTROTYPING. 69
may be cut open from top to bottom and the object removed ; the mold will now sprinj^ into its original position and shape. The tendency of this composition to absorb water may be prevented by immersing the mold in a weak solution of bichromate of potash and drying in the sun. An insoluble coating is thus secured.
A list of materials suitable for molding composition might be extended to include nearly any inelastic sub- stance which can be sufficiently softened to receive an impression from type or cuts with a reasonable degree of pressure. At this writing admirable results are being obtained from pure lead under the name of the Doctor Albert process, a description of which will be found in another chapter. However, there is no mate- rial which, for general work, equals in popularity pure ozokerite or ozokerite mixed with a little beeswax. Freedom from lumps, fiber or grain insures a perfect medium for the production of the finest lines and shades of engraving. It may be easily softened by heat to the degree most suitable for molding and will not perceptibly shrink in cooling or recover its form after receiving an impression. Moreover it takes black- lead readily, is unabsorbent and may be used over and over innumerable times. In this age of adulterations it is not always easy to obtain pure wax, but most adulterations may be detected. The materials which are most commonly mixed with wax are paraffin, resin and tallow, and the presence of these substances may be suspected if the fracture is smooth instead of granular.
To prepare wax for molding it should be melted in a steam-jacketed kettle and heated for several hours to
70 ELFXTROTYPING.
expel all the moisture. About ten per cent of crude turpentine and five per cent blacklead should then be added and thoroughly incorporated. Having been thus prepared the wax is dipped out and poured through a strainer upon some shallow trays of brass or other metal and allowed to cool. These trays, or cases, are sometimes made of brass plates of a convenient size with the edges raised about one-fourth of an inch so as to form a shallow pan. Such cases are, however, quite expensive and entirely unnecessary, as a perfectly flat plate made of electrotype backing metal will serve the purpose even better than brass, for in the event of its becoming bent or warped it may be easily straightened by simply laying it on a flat surface and planing it down with a hammer and block. A raised edge may be obtained by surrounding the case with wood or metal strips of suitable height. It is customary to place the cases on a stone or iron table large enough to accom- modate several at the same time and located within convenient distance of the wax-melting pot. When a stone table is employed for the purpose it should be very thick, not less than five or six inches, in order that it may quickly absorb the heat from the cases and thereby facilitate the cooling of the wax, otherwise much time would be consumed in waiting for the wax to set sufficiently to stand handling. Even a heavy stone table, unless of extraordinary size, will not cool cases fast enough when the volume of work is consid- erable, and under such conditions it is advisable to employ a hollow iron table provided with water and waste connections so that a circulation of cold water may be maintained and the time required to cool the
ELECTROTYPING. . 71
cases reduced to the minimum. Such a table may have, permanently secured to its surface a strip of iron, three-eighths of an inch thick, extending entirely around the outside edge. The flat cases, about one- eighth of an inch thick, are then laid on the table and wax poured on them until it reaches the height of the ^-inch strips. The cases may be separated, if desired, by strips of wood. After the wax has set, the cases are cut out with a knife and removed from the table, and the residue returned to the kettle. The iron table may be made still more effective by providing it also with steam connections, for it often happens on a cold morning that the table is too cold to cast perfect cases, and considerable time is consumed in producing the proper temperature by outside influences. In pouring the wax on the cases it is always advisable to strain it and thereby insure the exclusion of all dirt or foreign matter which may have found its way into the melting kettle. Immediately after pouring, a straight-edge or wire should be drawn over the surface of the cases to remove any air bubbles which may have formed. Any bubbles which do not yield to this treatment may be lightly touched with a gas flame. Neither wax nor com- position material can be used for molding until some time after it has been cast in cases, or until it has had time to cool, and it is therefore the practice to cast cases several hours in advance of the time they will be required for use.
Molding presses operated by steam or hydraulic power are usually provided with devices for indicating the depth of impression made in the wax, or with auto- matic stops for shifting the belt when the impression
72 ELRCTROTYPINO.
has reached a predetermined depth. Such devices are effective only when the wax cases are all of the same thickness and of imiform temperature. The tempera- ture of the wax determines its degree of plasticity, and the suitable degree is indicated when the wax will yield under pressure of the thumb. The ability to judge the correct temperature comes with experience, and can be acquired in no other way.
By exercising due care to fill the cases level with the bearers which surround them, the waxcaster may produce cases reasonably uniform as to thickness ; but to insure absolute accuracy they should be passed through a wax-shaving machine, which not only in- sures uniformity but also removes any dirt or dust which may have become attached to the wax while in a liquid or semi-liquid state.
When wax cases are cast several hours in advance of their use and have become cold and brittle, it is necessary, before molding, to restore them to a plastic condition, as any attempt to mold in cold wax would be not only dangerous alike to press and form, but would inevitably result in failure. The wax is sometimes softened by laying the cases on a steam-heated table, such as is illustrated in Fig. 8, first placing some strips of wood on the table to protect the back of the case from excessive heat. Unless so protected, the wax next the case would become much softer than the face,' and the result of molding from a case thus unevenly heated would almost certainly be concaved faces in the reproduced type and cuts. Even when great care is observed in warming the cases, it sometimes happens that this defect occurs in the electrotype, and for this
ELECTROTYPING.
7;?
reason as well as to avoid delay it is advisable to keep the cases in a box moderately heated by steam or hot air where they will be gradually brought to nearly the proper temperature for molding. They will then require an exposure of but a few moments on the steam table to make them sufficiently plastic. Instead
Fig. 8. Electrotypers' Wax Kettle and Table.
of a box, a number of pigeonholes may be constructed about two feet above the steam table in such a manner that the cases may rest on their edges in a vertical position, and the hot air arising from the steam table permitted to circulate between them.
Having warmed the case until the wax will take an
74 ELECTROTYPING.
impression of the thumb, it is given a thorough coating of molding graphite, which, when properly applied, prevents the wax from spreading. Graphite should also be applied to the form, rubbing it in thoroughly with a brush in order to prevent the type or cuts from adhering to the wax.
The form is now placed on the apron of the mold- ing press and the case inverted upon it, or if the form is small the operation may be reversed and the form inverted upon the case. In either event two or three sheets of heavy strawboard should be placed between the back of the case and the press to prevent too sud- den chilling of the wax. Having been thus prepared, the form and case with its strawboard backing are slid under the head of the molding press and pressure applied until sufficient depth of impression has been obtained in the wax, when the form and mold should be carefully separated and examined.
It will sometimes be found necessary to take a sec- ond impression in order to obtain a perfect mold, and in such cases it is obvious that the utmost care must be exercised to prevent a doubled impression. To provide for such contingencies, forms which are to be electro- typed should be imposed in such a manner as to leave an opening between the sections of furniture at two of the corners of the chase, that the molder, when setting the form the second time, may accurately locate the first impression.
When a large number of duplicates are required from one form it is customary to prepare a sufficient number of electrotype patterns to fill a chase and there- after mold from the patterns instead of the original
ELECTROTYPING, 75
form. When the patterns are carefully prepared no building- will be required on the molds, and much of the labor of finishing will also be saved.
The operation of the molding press is sufficiently explained by the illustrations Figs. 9 and 10. With the exception of the hydraulic press the principle by
Fig. 9. Electrotypers' Hand Molding Press.
which pressure is applied is the same in all molding presses — a toggle joint operated by a screw. In the hand press the screw terminates in a hand wheel whose spokes extend beyond the rim of the wheel to provide a convenient means of applying power. The screw in a power press terminates in a large gear wheel which is engaged by a pinion driven by steam power.
70 . Ki.iarrkoTvi'iNc.
The press illustrated in Fig. lo is provided with an indicator consisting of a finger and graduated dial, by means of which uniformity in depth of impression may be obtained. The indicator is particularly useful when two or more impressions are required, for, having noted the location of the finger on the dial plate at the
Fig. io.
Electrotypers' Power Molding Press.
completion of the first impression, it is an easy matter to determine the depth of the second.
In connection with the operation of the molding press mention may be made of a fact not always recog- nized by molders, which is, that the greatest power exerted by a toggle joint occurs just before the toggles
ELECTROTYPING. 77
reach a perpendicular position. The amount of pack- ing placed under the case is sometimes so excessive that the toggles never reach the point of highest effi- ciency, and therefore more or less power is unneces- sarily expended in producing the impression. While this is of no particular moment in the case of the steam press, except as it throws a heavy strain on the yoke, a proper adjustment of the packing would save consid- erable hard labor to the operator of the hand press.
78 ELECTROTYPING.
CHAPTER XL
BUILDING.
MOLDING a form or pattern naturally causes more or less displacement of wax, which is forced up around the edges of the form and between the cuts or type, or wherever there is an opening, however small. Before proceeding to metallize the mold, it is necessary that these displacements shall be cut down to a uniform level, for it would not only be difficult to metallize, by the usual methods, a mold whose surface consists of knobs and protuberances of uneven heights, but it would also be impossible to cast the electrotype plate within the limits of the thickness usually required for printing purposes, for every protuberance on the mold would necessarily involve a corresponding depression in the shell; and inasmuch as the shell must be backed with metal and entirely covered thereby, the thickness of the finished electrotype plate could not be less than the highest point of the shell. As a rule, electrotypes are made not more than one pica in thickness, and the lowest depression in the electrotype where blank spaces occur must obviously be somewhat less than a pica in depth.
ELECTROTYPING. 79
For the purpose of cutting down the mold a wax knife (Fig. ii) of special design is employed. The mold and the knife should be warm, and the knife must be occasionally heated over a gas jet or stove. The dis- placed wax is removed by a shaving, outward cut of the knife, taking care not to cut too deep into the mold.
Fig. II.— Wax Knife.
The operation requires some practice, but is easily accomplished if the knife blade is kept warm ; other- wise there would be danger of breaking down, or dis- torting the walls of the cavities of the mold, in which case the later operation of blackleading or metallizing the mold would be rendered difficult if not impossible. Even a sharp, warm knife will leave the edges of the walls more or less ragged, but these edges may be ren- dered smooth and rounded by passing rapidly over the mold a lighted gas jet attached to a rubber hose.
After the cutting-down process, the operator should go carefully over the mold with a sharp-pointed tool and pick out any shavings or particles of wax which may have become lodged in the indentations.
The mold should now present a reasonably smooth surface, all the high places caused by displacement hav- ing been cut down to a uniform level, which leaves the indentations in the mold from ^^ to ^^ of an inch deep.
80 ELECTROTYPING.
If the mold has been made from a soHd type form, it may now be metaUized and prepared for the depositing vat; but if made from an open form, the blanks between the printing surfaces must be raised in order to produce a depression in the electrotype and thus eliminate all possibility of smutting in printing. Unless the blank is raised or built up in the mold, it would be necessary to deepen the depression in the electrotype by routing or chiseling, which is a much more expensive operation than building, particularly when a number of duplicates are required from one pattern. Building is an operation requiring a steady hand and a quick eye as well as a skill which comes from long practice. The tools em- ployed are a building iron (Fig. 12), a small gas stove
Fig. 12.— Building Iron.
and a strip of wax. The building iron is a smooth, cone-shaped block of copper, about two inches long, one inch in diameter at one end and tapering to a sharp point at the other, with a handle eight or ten inches in length inserted in the side. Several of these irons should be provided in order that while one is in use the others may be heating. To build up a blank in the mold, the operator takes a hot iron in one hand and a strip of wax in the other, and, holding the point of the iron over and close to the blank which is to be raised,
ELECTROTYPING.
81
touches the iron Hghtly with the strip of wax, which instantly melts and runs down the iron onto the mold. If the blank is large, the wax is held in contact with the iron while it is moved over the space back and forth until entirely covered and built up to the required height.
Care must be -taken not to get the iron too hot, for in that case the wax would be made too thin and would not chill quick enough by contact with the mold, but would run off from the blank and into the indentations of the mold. It is always advisable to test the heat of the iron by running some wax onto the edges of the mold where no damage can result. Before blackleading or metallizing the mold it is also necessary to provide places of contact for the electrical connections.- This may be done in various ways. The simplest method is to provide two pieces of copper wire, about ts of an inch in diameter and six or seven inches longer than the case. One end of each wire should be turned over to form hooks by means of which the case may be suspended from the cross rods of the depositing vat. The wires are heated by dipping them in the metal pot or in any convenient manner, and are then laid on the case, one on each side of the mold, where they become embedded by melting a channel for themselves in the wax.
Additional security is obtained by covering over the wires with wax by means of the building iron. This method of providing electrical connection with the mold is simple and reasonably secure, if the case is not too heavy ; but a better method consists in substituting for the wires strips of thin sheet copper from one-half to one 6
82 ELECTROTYPING.
inch in width. These strips are not designed to sustain the weight of the case, but simply to act as conductors, and for this purpose are superior to wires, because they assure a better contact with the cross rods. When this connection is employed, the weight of the case is sus- tained by S-hooks, one end of which is passed through a hole in the case, and the other end, which should be insulated, hooked over the cross rod.
There are several other methods of making elec- trical connections with the molds which are valuable chiefly as time-savers. One of them is shown in the illustration. A piece of copper or brass is melted into the mold near the top and makes contact with a portion of the hook which suspends the case from the cross rod of the bath.
ELECTROTYPING. 83
CHAPTER XII.
METALLIZING.
THE utility of electrotyping in its early days was restricted to the reproduction of medals or other metallic objects which were conductors of electricity, but in 1840 Mr. Murray discovered that nonmetallic objects could be made conductive by applying to their surface a film of graphite (blacklead), and to this dis- covery is largely due the successful application of elec- trotyping to the copying and duplication of engravings and type forms. Only the purest grades of graphite containing from 95 to 99 per cent of carbon are used for metallizing. For this purpose it is ground to a seemingly impalpable powder, but under the microscope it is found to consist of minute flakes. To metallize or render conductive a nonmetallic object, it is essential that these flakes shall lie flat upon it like the scales of a fish, overlapping each other and forming a continuous and unbroken metallic covering for the object. Such a surface can be obtained only by brushing or otherwise forcing the flakes into the position described, which will incidentally give to the object a bright polish. Black- leading is sometimes accomplished by means of a pump
84 ELECTROTYPING.
or air blast, as will be hereafter described, but the usual method is to apply the graphite with a soft brush of camel's or badger hair, either by hand or with a black- leading machine. For blackleading by hand a camel' s- hair brush is preferred. With this instrument the graphite is brushed back and forth over the mold until a bright polish is obtained, and until it is certain that no spot, however small, has been neglected. If so much as a punctuation point fails to receive the proper polish, copper will not deposit thereon, and a hole in the shell will result.
Blackleading by hand is a slow and disagreeable task, and is seldom practiced in American foundries, a blackleading machine being considered essential even in the smallest establishments. Fig. 13 illustrates a blackleader which is a type of the machines in general use at the present time. While there are variations in the mechanical movements of different machines, the essential features are a vibrating brush or brushes, and a reciprocating bed to carry the molds back and forth under the brushes. The apparatus is all inclosed in a tight box which confines and prevents waste of graph- ite. After the mold has been built up and prepared as previously described it is placed on the bed of the blackleader and covered thickly over with graphite. When the machine is started the molds travel slowly back and forth while the rapidly vibrating brushes soon effect the necessary polish. The time required to prop- erly blacklead a mold depends upon the nature of the work and the speed at which the brushes are operated.
ELECTROTYPING.
85
A mold of a type form requires considerable more brushing than a flat engraving because of the minute
Fig. 13.— Blackleader.
indentions made by the punctuation points, etc. With a double-brush machine running at about 600 revolu-
86 ELECTROTYPING.
tions per minute, a good polish is usually obtained in from five to ten minutes.
A disagreeable feature of blackleading is the flying dust, which cannot be wholly confined and which even- tually covers everything in the molding room, including the workmen. This annoyance is minimized by the use of the inclosed blackleading machine but not entirely eliminated. On this account the wet process of black- leading is sometimes preferred. This method was invented and patented by Mr. Silas P. Knight in 1872. By this process the graphite is mixed with water to the consistency of thin cream and by means of a rotary force pump is discharged with considerable force upon the mold through a traveling rose nozzle, the entire appara- tus being confined in a water-tight box. In another form of wet blackleader the emulsion of graphite is forced over the mold by a paddle wheel which revolves in the liquid. The blades of the wheel consist of badger-hair brushes which come lightly in contact with the mold and assist in producing the necessary polish. The wet process is said to be entirely satisfactory, but for some reason has never come into general use.
Various attempts have been made to perform the
operation of blackleading by means of a blower or air
blast, and several patents have been issued for machines
with this design. Fig. 14 illustrates a machine which
combines both the air-blast and brush features. Air
from the pressure blower (on the floor, back of the
machine) passes through tubes in the horizontal cylinder
(above the machine) and is discharged through a narrow 6
ELECTROTYPING.
87
slot extending across the table and close to the mold ; water circulating outside the tubes reduces the tempera-
FiG. 14.— Combination Blackleading Machine.
ture of the compressed air, so the machine may be oper- ated continuously — even in the summer — without dan- ger of injury to wax molds. At the bottom of the
88 ELECTROTYPING.
machine there is a shallow drawer with a gauze bottom through which the air passes to the blower ; the gauze retains particles of wax and other substances likely to obstruct the free passage of air through the slot. How- ever, should the slot become clogged, by removing the plate on the front of the machine the workman can obtain access to the wind chest and may easily clear away any obstruction. By a glance at the mercury gauge, on the top of the machine, the operator can see whether the air pressure is as it should be. The brush, which is of badger hair, is located just back of the wind chest and actuated from a shaft supplied with a tight pulley, so, whenever desired, the brush may be stopped. The distance of the brush from the table is adjustable.
In operation the workman lifts the cover, at front, which is held raised by a hook shown at the left side, lays the cases to be leaded on the table, which is 33 by 22 inches, lowers the cover, and starts the machine by pulling the handle on the right until a pawl drops into a notch in the rod ; he then adjusts the stop motion so the table will make one, two or three trips forward and back; when these have been completed the pawl will be detached automatically from the rod, and the spring on the countershaft carry the belt on the loose pulley, stop- ping the machine. It is claimed by the manufacturers that a tableful of molds may be metallized in one minute.
After the mold has been blackleaded, it must be thoroughly freed from the loose graphite which would otherwise remain in the depressed portions, particularly
ELECTROTYPING. 89
in the smaller indentations made by punctuation points and leaders, and cause defective shells. The removal of the superfluous graphite may be effected by a hand bellows, but in large establishments a rotary fan opera- ted by power is sometimes employed. A still better method consists in taking the air through a tube from a reservoir in which it has been compressed by an air pump. By this method sufficient pressure to thor- oughly blow out the mold is assured. From such a reservoir additional tubes may be extended to the molding presses, and utilized to blow the loose graphite from the molds as may be necessary during the opera- tion of molding.
By the process of blackleading, the case is rendered conductive over its entire surface, and should it be sus- pended in the bath without further preparation, it would receive a deposit of copper not only upon the mold but upon the margin of wax surrounding the mold, and upon the back of the case. To restrict the action of the current to the surface upon which a deposit is desired, the remaining portion is painted out with hot wax or varnish, or its conducting surface is destroyed by passing lightly over it a hot building iron. The conductivity of graphite is only .07 of one per cent as compared with pure copper, 100 per cent, and the action of the electric current on a blackleaded mold is therefore very slow until covered with a coating of cop- per, when deposition proceeds rapidly. To give the mold a better conducting surface than is provided by the graphite, and thus facilitate immediate action of the
90 ELECTROTYPING.
current over its entire surface, it is customary to precipi- tate a film of copper on the mold before placing it in the bath. This preliminary coating of copper is pro- duced by pouring on the mold a solution of sulphate of copper of about i6° Baum6, and covering it with a sprinkling of iron filings. With a badger-hair brush the filings are lightly distributed over the mold until thoroughly wet, when they take up the acid in the solu- tion, and the copper thus set free is precipitated in a bright film on the mold. If any portions of the mold fail to take the coating the operation is repeated. Par- ticular care is observed to avoid scratching the mold with the iron filings.
Flat molds such as are made for the production of copper printing plates may be readily and effectively metallized by either of the methods previously described, but for the production of nickel electrotypes or the reproduction of irregular shaped objects such as stat- uary, or art work of various kinds having undercut or deep portions, recourse must be had to what is called metallizing by the wet way. While this class of work is not strictly in the line of commercial electrotyping it is sufficiently analogous to deserve mention. The processes to be described are recommended by such practical writers as Langbein, Urquhart and Watt. Gutta-percha or wax molds have their surfaces rendered conductible by the following plan : Take equal parts of albumen (white of egg) and a saturated solution of common salt, and apply the mixture to the object to be coated by means of a soft brush. Then dry the compo-
ELECTROTYPING. 91
sition thoroughly. Now make a strong solution of nitrate of silver and dip the mold into it for a few min- utes and dry again. Expose the mold to a strong light until it becomes quite black. The mold is then to be dipped into a saturated solution of sulphate of iron, when a layer of metallic silver will be formed upon which a deposit of copper may readily be obtained. The mold should be rinsed when taken from the sul- phate of iron solution and connecting wire attached to it, when it may at once be placed in the depositing bath.
Another method of metallizing is as follows: Dis- solve a piece of phosphorus in two drams of bisul- phide of carbon, stir in two drams of benzine and a drop or two of sulphuric ether; pour the whole into half a pint of alcohol and wash the surface of the mold with this mixture twice, allowing it to dry after each application.
The silver solution is made by dissolving one dram twenty grains of nitrate of silver in a mixture of half a pint of alcohol and one dram of acetic acid. The mold is thoroughly floated once with this solution and allowed to dry spontaneously.
Another and simpler method of rendering the mold conductive may be described as follows : Dissolve phos- phorus in pure alcohol until a strong solution is obtained and wash the mold with the mixture. The silver solution is prepared by dissolving nitrate of silver in aqueous ammonia to saturation. It is to be poured evenly over the mold and allowed to float over it for a few minutes. The solution is poured off and
92 ELFXTROTVPING.
the mold allowed to become partly dry, when it is again floated with the mixture. Spots that do not appear to take the solution readily should be wetted with it by means of a soft brush.
Still another process is as follows: Apply with a brush upon the mold a not too concentrated solution of nitrate of silver in a mixture of equal parts of distilled water and ninety per cent alcohol. When the coat is dry, expose it in a closed box to an atmosphere of sul- phureted hydrogen. The latter converts the nitrate of silver into sulphide of silver, which is a good conductor of the current. For the production of the sulphureted hydrogen, place in the box, which contains the mold to be metallized, a porcelain plate or dish filled with dilute sulphuric acid (i acid to 8 water) and add five or six pieces of iron pyrites the size of a hazelnut. The development of gas begins immediately and the box should be closed with a well-fitting cover to prevent inhaling the poisonous gas; if possible, the work should be done in the open air or under a well-drawing chim- ney. The formation of the layer of sulphide of silver requires but a few minutes, and, if not many molds have to be successively treated, the acid is poured off from the iron pyrites and clean water poured upon the latter so as not to cause useless development of gas.
For coppering leaves, plants, flowers, etc., dissolve five parts (by weight) of wax in five of warm oil of turpentine, and add to the solution a mixture of five parts of phosphorus, one of gutta-percha and five of asphalt in 120 bisulphide of carbon. When both are
ELECTROTYPING. 93
thoroughly mixed, add to the whole a solution of four parts (by weight) of guncotton in sixty of alcohol and sixty of ether, and, after a thorough shaking, allow to settle. The next day pour off the clear solution from the sediment, when the solution can at once be used. A French process for metallizing leaves, etc., con- sists in immersing them in iodized collodion composed of forty per cent alcohol, 40 cubic centimeters; ether, 60 cubic centimeters; potassium iodide, i gram; gun- cotton, I gram. Allow the leaves, etc. , to dry so that a firmly adhering layer is formed; then immerse them in a solution of ten parts (by weight) of nitrate of sil- ver in 100 of water, whereby a layer of iodide of silver is formed. Now expose the article thus treated for some time to the light, and then immerse it in the reducing fluid consisting of water, 500 parts; green vitriol, 25 parts, and acetic acid, 25 parts. The reduc- tion of silver proceeds rapidly and the articles are soon ready for coppering. Instead of the iodized collodion, a mixture of equal parts of white of egg and solution of common salt may be used.
94 ELECTROTYPING.
CHAPTER XIII.
THE CONDUCTORS.
THE electrodes and all connections between the dynamo and the molds or anodes should be of copper and should be amply large to conduct, without heating, the strongest current practicable to use in the depositing process. It should be remembered that the generation of the electric current requires power, and that a portion of the power is always expended in over- coming resistance, and is, so far as its effect on the work is concerned, wasted. It is obvious, therefore, in the interest of economy, that due precaution should be observed to provide both in the conductors and in the bath a path of minimum resistance. A barrel of water would run out of an inch bunghole in a very few min- utes, while it would take a tremendous pressure to force the same quantity of water in the same time through a gimlet hole. In the same way a current of several hundred amperes will flow readily through a large rod, when the attempt to force the same current through a small wire would result in overheating the wire and the dynamo, with a consequent waste of power. ' ' The development of heat in the conductors or the solution is proportional to its resistance and is proportional to the
ELECTROTYPING. 95
square of the strength of the current. Hence, the development of heat will be the greater, the smaller the cross-section of the conductor and its conducting capac- ity are, and the larger the quantity of current which passes through it."
The size of the conducting rods required for electro- typing depends, therefore, on the quantity of current to be employed at one time, which may be estimated with sufficient accuracy by multiplying the area of the cath- odes in square feet by the number of amperes required to deposit one square foot at the maximum practicable rate. Curiously enough there is a wide divergence of opinion among authorities as to the quantity of current which may be advantageously employed. V. Hiibl gives the maximum as 36 amperes with an agitated solu- tion. Sprague and Watt place the maximum at 37 amperes, while other writers claim that from 75 to 100 amperes may be employed. It is probable, however, that the latter estimates are made without considerations of economy. It would no doubt be possible to employ 100 amperes, but at a tremendous waste of power in overcoming the resistance due to polarization, which increases " at a rate approaching that of the square root of the current. " It is probable that 50 amperes per square foot cannot be exceeded, if consideration be given to economical working.
Depositing vats vary in dimensions, and for that reason a conducting rod which would be of ample capacity in one case would be too small in another. Inasmuch as the difference in the cost between a small
96 ELECTROTYPING.
rod and a large one is inconsiderable, it is always wise to err on the side of safety. The text-books recom- mend a cross-sectional area in the conductor of one square inch for each 500 amperes, and in practice, rods of this size have been found to be of ample capacity. The resistance of a conductor is proportional to its length as well as to its cross-sectional area, and this rule applied to electrotyping means that the dynamo should be located in the immediate neighborhood of the depos- iting vats. For the purpose of conducting the current, the cross rods, i. e., the rods from which the anodes and molds are suspended, do not usually require to be more than one-fifth the size of the main conductors, but inas- much as it is their province to sustain the weight of the heavy anodes they should not be less than one-half inch in diameter.
Less trouble will be found in making good connec- tions if the main conducting rods are rectangular in shape, as in that case the cross rods which rest upon them will have a larger area of contact surface, particu- larly if the ends are slightly flattened. If the main conductors are round, the ends of the cross rods should be not only flattened but curved to fit over the larger rods, and thus insure a good contact. The anodes are usually suspended in the solution by two copper hooks, which should be large enough to transmit the current without becoming sensibly heated — say three-eighths of an inch in diameter. These hooks, like the cross rods, should be flattened and curved in order to insure ample contact surface. Undoubtedly the best method of
ELECTROTYPING. 97
suspending the anodes is to drill and tap holes in the ends and screw the suspending hooks into them. This makes a perfect connection, and will remain as long as the anodes last.
It has been frequently noted that electrotypers do not always appreciate the importance of making good connections. It is of no avail to provide large conduct- ing rods and cross rods if the conducting capacity of the rods is to be choked off at the point of connection, which is what occurs when one round rod is laid across another round rod. It should be plainly obvious that unless one or both of the rods are flattened where they come in contact, the area of the contact will be extremely limited compared with the area of the conductors on both sides of the contact. It is hardly necessary to say that all contact points should be kept clean and bright. A neglected rod will soon become corroded, and corro- sion increases resistance and is a frequent cause of heat.
It should not be forgotten that the solution is a con- ductor of the current in the same sense that the rods are, and should be considered in that capacity as well as a dissolving medium. Pure sulphate of copper solu- tion is an extremely poor conductor. The addition of sulphuric acid improves its conductivity, but under the most favorable conditions its resistance is several million times greater than copper. To reduce this resistance to a point where the solution will not become appreci- ably heated by the passage of a strong current it' is necessary to provide an exceedingly large area of con- ducting fluid and to suspend the anodes and cathodes
7
98 ELECTROTYPING.
as near together as possible, say two to three inches apart. According to Joule's law, previously quoted, the development of the heat will be the greater the smaller the cross-section of the conductor and its con- ducting capacity are, and the larger the quantity of current which passes through it. If, therefore, it is desired to employ a very strong current, the vats must be larger in proportion to the size of the anodes than would be necessary with a moderate current. It is safe to say that the cross-sectional area of the solution should be at least double the area of the anodes.
ELECTROTYPING. 99
CHAPTER XIV.
DEPOSITING.
WHEN a mold has been metallized by the dry graphite method, and before proceeding to strike it (i. e., precipitate on its surface a preliminary coating of copper to render it more conductive), it is essential that the air shall be expelled from its surface by thoroughly wetting it, otherwise the mold when first immersed in the bath will be apt to repel the liquid, and the film of air retained on its surface will partially insu- late the mold and cause holes in the shell. Wetting may be accomplished by pouring over the mold a small quantity of alcohol or wood spirits. A more economical method consists in placing the mold face up on a shelf in a tank partially filled with water in such a manner that it will rest an inch or two under the surface, and then by means of a rotary pump and a rose nozzle direct a stream of water upon it. In some foundries graphite is mixed with the water, in which case the apparatus becomes an auxiliary blackleader and aids in the metallization of the mold.
After wetting and striking the mold it should be immediately suspended in the bath from one of the rods connected with the negative pole of the dynamo or bat-
100 ELECTROTYPING.
tery. It will be recalled that the current enters the bath through the positive electrode and leaves it through the negative. It is obvious, therefore, that were the mold suspended from the positive rod no action would result.
The anodes are solid plates of rolled copper of any convenient thickness, but they should have as nearly as possible the same area of exposure as the cathodes. If the anode be much smaller than the cathode the deposit will be brittle and the solution become impoverished. If the anode should be much larger than the cathodes copper will be dissolved faster than it is deposited, increasing the density of the solution and resulting in streaks on the back of the electrotype and the forma- tion of uneven deposits.
Holes in the shell are usually due to defective black- leading or failure to expel the air from the mold by thorough wetting. In some instances, however, they are caused by hydrogen bubbles. The remedy for the latter evil is to decrease the current strength or pass a camel' s-hair brush lightly over the mold several times during the time it is in the bath, or, better yet, agitate the solution.
The mold should be examined after it has been in the bath a few minutes, and if any dark spots are observed it should be at once removed and a solution of graphite and water, or, better yet, graphite and alco- hol, should be thoroughly rubbed into the defective spots. The mold should then be rinsed under a strong head of water applied through a spray nozzle and
ELECTROTYPING. 101
returned to the bath. On no account should the mold be allowed to dry while out of the bath.
The anodes should, of course, be suspended from the positive pole of the dynamo, and it is evident that only one anode need be provided for each pair of cathodes, for, to maintain an equal area of exposure, a mold should be placed on each side of the anode.
If the baths are arranged in series, which is the most economical method of working, the total number of molds should be divided as evenly as possible between the vats to insure an equal rate of deposition.
The copper sulphate solution requires little attention as a rule, because the proportions of its ingredients may be quite widely varied without materially affecting the quality of the deposited copper, and, on the other hand, the current strength may also be varied and the quality of the production still remain satisfactory; but, notwith- standing these facts, it is possible to make the solution too rich or too poor in metal, or too weak or too strong with acid, and the current density may be too great to work in harmony with the solution. Very often a defective shell may result from one of two or three causes. It is, therefore, sometimes necessary to experi- ment a little in order to determine the exact cause of the trouble. For instance, a sandy, pulverulent deposit may be caused by an excess of current, or it may be caused by an excess of metal in the solution, or both. A brittle deposit will be caused by a weak current, or a solution poor in metal, or both. But if the electro- typer be provided with an accurate voltmeter it is a
102
ELECTROTYPING.
comparatively easy matter to locate the cause of the trouble, for if the instrument indicates a current of suit- able tension for a properly proportioned solution, it may be assumed that the cause of the defective deposits will be found in the bath and may be removed by enriching or diluting the solution as may be indicated by the char- acter of the deposited copper.
Under ordinary conditions of current and solution, the molds should be separated from the anodes by a distance of about two inches; but if it is found that the deposit is very dark in color or granulated in texture, this distance may be increased, thereby increasing the resistance of the solution, which is equivalent in its effect to cutting down the current strength.
After working a few hours the anodes become more or less coated with slime, consisting of impurities and small quantities of foreign metals, which are always present to a greater or less extent in rolled copper. To remove the slime, which has the effect of partially insu- lating the anodes, they should be removed from the bath once every day and thoroughly scrubbed and rinsed with clean water.
When molds are removed from the bath the anodes should always be disconnected from the dynamo, as otherwise copper would be dissolved into the solution, thereby unduly increasing its density.
The length of time required to deposit a shell of given thickness depends on the current - strength em- ployed and the condition of the solution and connec- tions. According to Gore, a current density of 17.94
ELECTROTYPING. 103
amperes per square foot will deposit .001 inch of copper per hour; 35.88 amperes will deposit .002 per hour, and so on. Having ascertained the current-strength avail- able there would be no difficulty in calculating the time necessary to obtain a deposit of any required thickness provided it were certain that no variation in the current would occur, and that the connections would remain clean and in perfect contact, for having once ascertained the time required to deposit a satisfactory shell, it would be safe to assume that the same results would be obtained thereafter; but carelessness in the preparation of molds, as well as dirty rods or connections, sometimes delays the action of the current, and the electrotyper, after the calculated time, usually separates one corner of the shell from the mold with a sharp-pointed tool, and tests its thickness by bending it back and forth. This would seem to be a " rule-of-thumb ' ' method of working, but constant practice makes the workman so expert that he seldom makes a mistake. In establishments where the volume of work is large, it is customary to provide time tags which may be attached by clothes pins or other devices to the molds or cross-rods. When the mold is suspended in the bath, a tag is attached on which is written the hour it is due to come out. In this way the electrotyper is enabled to keep tab on his work and avoids waste of time in testing work which has been insufficiently exposed; for while it sometimes happens that a longer time is required to deposit a shell than would be indicated by the voltmeter or ammeter, it never takes less than the time so indicated.
104 ELECTROTYPING.
The electrotypers' sink should be of ample dimensions and should be provided with an unlimited supply of hot and cold water. The cold water faucet should be a hose bib, to which should be attached a short piece of hose terminating in an adjustable nozzle, to provide either a spray or a strong stream of water as circumstances may demand. The hot water should be kept in a tank at one end of the sink, from which it may be dipped as needed. One end of the sink should be provided with a hinged apron to protect the operator and the floor from the spray when using a strong head of water such as is necessary in washing out molds.
ELECTROTYPING.
105
CHAPTER XV.
CASTING,
ELECTROTYPERS' furnaces were formerly con- structed of brick with an iron kettle and face plate. These furnaces are, however, seldom seen now, the modern furnace (Fig. 15) being constructed of iron, lined with fire brick. It occupies less room than the old style furnace, is set up several inches from the floor to provide an air space underneath and thus minimize the
Fig. 15.— ELECTROTYPERS' Furnace.
106 ELECTROTYPING.
danger from fire, and it may be moved from one place to another when desired without tearing it to pieces. The kettle is square or oblong in shape, for convenience in floating the backing pans, and is about six inches
Fig. i6.— Leveling Stand.
deep, A wide flange or shelf extends around the top of the furnace to provide a convenient resting place for the backing pans and body molds. The floor vmder the furnace and for some distance in every direction should be covered with heavy sheet iron, about No. i6 gauge.
The leveling stand (Fig, i6), upon which the back- ing pans rest while the cast is poured, is a light but substantial framework of iron, whose upper rails are provided with T-screws which may be so adjusted as to
ELECTROTYPING.
107
keep the pan always in a level position and thus insure a cast of uniform thickness.
The backing pan (Fig. 17) is a plate of iron or steel, planed perfectly true and surrounded with a raised edge whose height determines the thickness of the cast. The pan is provided with handles to facilitate handling. Where the pans are large it is customary to handle them by means of a crane with an arm of sufficient length to swing them from the furnace to the leveling
Fig. 17.— Backing Pan.
stand. Backing pans should always be kept perfectly clean, and to that end should be scoured after each cast. Unless they receive proper attention in this respect they will soon become rusted and totally unfit for the purpose for which they are designed ; for to assure a perfect cast it is essential that the shell shall lie perfectly flat upon a smooth and level surface.
Backing metal is composed of lead, tin and anti- mony. A popular mixture is lead 90 pounds, tin 5 pounds, antimony 5 pounds. However, the proportions of tin and antimony are sometimes varied. Some elec- trotypers prefer 4 pounds of tin and 6 of antimony, and others 6 pounds of tin and 4 of antimony. The
108 ELECTROTYPING.
requirements are that the metal shall be soft enough to straighten easily under the hammer and punch, yet not so soft as to crush down on the press, and it must contain tin in sufficient quantity to insure perfect adhe- sion of the metal to the copper shell.
Having deposited a shell of satisfactory weight, the mold is removed from the bath and placed in the sink in a slanting position. After cutting the connections, a small quantity of hot water is poured over the mold, beginning at the upper end and allowing it to flow down over every portion of its surface. The heat softens the wax and releases the shell, which should be carefully handled to prevent buckling or bending. After rinsing the shell in cold water it should be washed with hot potash to remove the film of wax which will still adhere to the copper. The shell may be placed on a slanting board over the lye kettle and scrubbed lightly with a soft brush, and then rinsed with potash and after- ward with clean water. Unless the shells are to be immediately backed up with metal, they should be placed in a shallow, lead-lined box partially filled with water slightly acidulated with sulphuric acid. If the shells are permitted to become dry they will tarnish and will not readily amalgamate with the backing metal.
In order to effectually unite the backing metal to the shells it is essential that the back of the shell shall be perfectly clean, and that it shall be first covered with a coating of solder or with tin foil, which becomes solder when mixed with the lead in the backing metal. Tin foil may be purchased in rolls of any desired width
ELECTROTYPING. 109
and thickness. A convenient size is five or six inches in width and about .002 inch in thickness.
To thoroughly clean the shell it should be brushed over with a solution of chloride of zinc, which may be prepared by dissolving scraps of sheet zinc in muriatic acid to saturation and adding twenty-five per cent pure water. The zinc should be dissolved in a wide-mouthed bottle in the open air, as the fumes given oflf are disa- greeable and poisonous. The zinc solution may be applied with a bristle brush, and the operation may preferably be performed on a glass-topped table or on a sheet of heavy plate glass placed on the workbench. Glass is preferred because it is not affected by acid and may be easily kept clean.
After cleaning with the tinning solution the shell is covered with tin foil and placed face down in the back- ing pan, which has been previously heated by floating it in the molten metal, whose temperature should be sufficiently high to scorch a piece of white paper with- out burning it. The tin will almost immediately melt and cover the shell with a thin coating. If preferred, the shell may be placed on an iron plate heated by gas instead of in the backing pan, the object being to melt the tin foil on the shell. After the tin is melted the backing pan should be immediately transferred to the leveling stand and the shells covered with molten metal, pouring it on slowly from a small ladle and holding the shell down with a stick or any convenient instrument if it shows any inclination to rise to the surface of the metal.
no ELECTROTYPING.
To expedite cooling of the cast a small blower may be placed on the floor under the leveling stand in such a manner that a stream of air may be directed against the bottom of the pans.
A device which is sometimes employed in connection with the backing-up process and which is claimed to
Fig. 19.
accomplish a material saving of time and labor is illus- trated in Fig. 19. The description is taken from the circular of the manufacturer.
The apparatus is designed to flatten the plates by pressure after the metal has been poured and before it has set and hardened. The process differs but little
ELECTROTYPING. • 111
from that hitherto employed, the new feature being the application of pressure, whereby much of the ham- mering and finishing is obviated.
The press has been so designed as to make it thor- oughly efficient and convenient, many suggestions from experienced electrotypers being embodied in its con- struction. Its operation is very simple, presenting no difficulties.
When the pan is lifted out of the metal pot the metal that adheres to the bottom of the pan is scraped off by a steel scraper attached to the front end of the press. On the inner sides of the frame of the press are rollers, seven on each side, upon which the pans move easily and quickly. The pan is set on the rollers on the front of the press and the shell backea as usual. Air is blown on the bottom of the pan from a pipe underneath, and on the metal from a pipe above, the object being to cool the cast evenly as well as quickly. When the metal has commenced to set, a sheet of thick asbestos, covered with powdered chalk or blacklead, is laid on top of it and the pan rolled under the platen. The blast is then turned on the bottom of the pan under the platen. The rollers under the platen are on springs, and depressed by the pressure on the pan until the pan rests on supports underneath. The asbestos and the rollers being elastic, the pressure is gradual and easy. The pan remains under pressure till the next one is ready, and is then pushed out to the back of the press and taken off. The blast pipes underneath are supplied with the press and provided with dampers.
112
ELECTROTYPING.
They are so arranged that connection can be made with
the pipe from the blower on either side of the press.
Electrotypes are usually mounted on wooden blocks
to make them "type high," but for certain purposes it
Fig. 20.
is desirable to mount them on metal bases, as, for instance, half-tone cuts and matter which is to be stereotyped, such as advertising cuts for daily news- papers. For the latter purpose electrotypes are made in standard widths, i. e. , single, double or triple column. The electrotype, after it has been backed up and straightened, may be tacked or soldered to metal bases which have been previously trimmed and shaved to the proper dimensions, but better results are obtained both in appearance and security by casting the base directly
ELECTROTYPING.
113
on to the plate by placing the electrotype face down in an iron mold and pouring molten metal on the back. The cover of the mold is provided with corrugations which form depressions in the metal, thus effecting a saving in material and at the same time producing a cast both light and strong and more easily handled than a solid metal cast.
Figs. 20 and 21 illustrate respectively a body mold and a section of a cast made therein. The bottom plate of the mold on which the electrotype rests is not shown.
Before making a cast all parts of the mold are floated in the metal pot until they are of uniform tem- perature with the metal. With a pair of pincers or tongs the bottom plate is then withdrawn from the metal and placed on two supporting blocks, one under either end, one of which is slightly higher than the other, so that the plate will have a pitch of about one-half inch. The frame of the mold is then laid on the bottom plate, the electrotype placed inside, the cover adjusted and the 8
114 ELECTROTYPING.
different parts clamped together with two iron haind clamps. The cover is somewhat shorter than the frame, which leaves an opening at the upper end to receive the metal. The temperature of the mold is sufficient to soften the backing of the electrotype, so that the new metal, which is poured slowly and cautiously, readily amalgamates with it. Having filled the mold, the cast may be cooled by swabbing the mold with cold water. As the metal cools it shrinks and more metal must be continually added until the cast is set.
Electrotype body molds are made in several standard sizes, from 6 to 41 picas in width and about 14 inches long. Electrotypes wider than 41 picas are cast in adjustable molds, an illustration of which is shown in Fig. 22. In such a mold electrotypes from one-half to four columns in width may be cast solid or cored. Eight cores of different sizes are usually provided, suitable for different kinds of work.
In some foundries the mold is cooled after the cast has been poured by partially immersing it in a tank of water. When employing this method it is important that the cooling shall be effected gradually, otherwise uneven shrinkage would result and the electrotype be injured or destroyed. A convenient means of handling the molds is by means of a small derrick which may be locked in any desired position and thus permit the grad- ual immersion of the mold in the water.
After the shell has been backed up, the cast is taken to the scrubbing trough and thoroughly cleaned with kerosene and powdered pumice stone applied with a
ELECTROTYPING.
115
moderately stiff brush, and finally polished and dried with soft sawdust. Great care should be observed in cleaning half-tones, as a slight scratch is sufficient to ruin them.
The backing pan will usually accommodate several shells, and after they have been cast and cleaned the
next operation is to saw the different jobs apart that that they may be separately straightened and finished. For this purpose an iron saw table is employed, of which Fig. 23 is an illustration. The mandrel is driven by a countershaft and pulleys which are furnished with the
116
ELECTROTYPING.
machine. The rear end of the table is hinged to the frame of the machine; the front rests on the end of a screw, terminating in a hand wheel, by means of which the top may be adjusted to any desired height for sawing mortices, etc. An adjustable side gauge and a sliding end gauge are necessary features if the saw is to
Fig. 23.
ELECTROTYPING. 117
be used for general work, and a glass saw guard for protecting the eyes of the operator from flying chips and sawdust is also essential.
Saw blades for cutting electrotype metal should have about the same temper as for sawing wood, and should not be of greater diameter than the nature of the work demands. A large saw is liable to wind and warp, while, on the other hand, if it projects but slightly through the work this tendency will be minimized. The diam- eter of the saw must depend, of course, upon the dis- tance between the saw mandrel and the table top. For instance, if the saw mandrel is three inches below the top of the table, a nine-inch saw would be required to give sufficient cutting surface above the table and allow for a reasonable amount of wear. In most machines, however, the mandrel is located within two and one-half inches from the top, or even less, thus permitting the use of smaller blades. For general use a cross-cut saw, eight inches in diameter. No. i8 or 19 gauge, and with about five points to the inch, is found most practical and convenient. Such a saw should be driven about 4,000 revolutions a minute.
To cut freely without sticking or filling up, saws should be kept sharp, round, evenly set, and the teeth should be filed all with the same angle and without hook. To keep the saw round, it should be jointed occasionally by elevating the table top until only the longer teeth of the saw project through the slot in the top, when they may be ground down with a piece of emery stone to uniform length. If the saw mandrel fits
1 18 ELECTROTYPING.
perfectly the hole in the saw and no more filing is done than is necessary to bring the teeth to a point, a perfect circle will by this method be obtained.
The saw may be set by laying it on a block of hare- wood and striking every alternate tooth with a hammer or punch, and then turning it over and repeating the operation with the remaining teeth. It requires consid- erable skill, however, to set a saw evenly in this way, and it is preferable, particularly for the novice, to use a carpenter's saw set which may be purchased at any hardware store.
To file a saw properly it should be clamped between two round blocks, about one inch thick and one inch less in diameter than the saw. The blocks may be clamped together on the saw by placing them in a vise. The saw should be filed straight across and should not hook or lean forward of a line drawn from the center of the saw to its periphery.
ELECTROTYPING. 119
CHAPTER XVI.
FINISHING,
THE duties of the electrotype finisher are to make the face of the electrotype perfectly flat and level, to repair defective letters, or cut them out and replace them with type; to repair defective rules, etc., and finally to bevel the edges of the plates if they are to be worked on patent blocks, or to mount them upon wooden or metal bases.
The tools required to properly straighten an electro- type are a light hammer, with one round face, Fig. 24; a set of punches, Fig. 25; a pair of calipers. Fig. 26, and a rubber, Fig. 27.
The first operation is to beat down the edges of the bearers surrounding the page or engraving with the hammer, after which the plate is laid face down on a smooth, steel-faced finishing block, and planed down with a block of wood and hammer to make it lie flat and solid. If any bad sinks are observed in the electro- type their exact location is marked on the back of the plate by means of the calipers. The plate is then again laid on its face on the finishing block, and with a suit- able punch the marked spot is driven down until it is flush with the surrounding matter. After the plate has been rough-finished and straightened it is taken to the rougher. Fig. 28, and a cut taken off the back, which reduces it to an approximately uniform thickness.
120
ELECTROTYPING.
As its name implies, the rougher was designed to take the first or rough cut ofT from the electrotype cast. Its chief utility consists in the fact that a large quan- tity of "metal may be removed at one operation. The electrotype rests face down upon a traveling bed, and
Fig. 24.
Fig. 25.
is held down during the operation of planing by two spring rolls located one on either side of the track of a reciprocating cutter. The cutter is secured in a tool post which is arranged to slide on an arm extending over the bed and at right angles thereto. The cutter is actuated by a pitman, one end of which is connected with a stud on the cutter head and the other with a stud
ELECTROTYPING.
121
on the drive pulley. The bed is operated in one direc- tion by a worm, which is driven by a belt from a pulley on the drive shaft, and is reversed by hand.
Fig. 26.
While the machine was originally intended for rough work, yet if carefully constructed it can be made to per- form its duty so accurately that no further planing or shaving is necessary, and in many foundries it takes the place of the shaving machine.
An improved type of rougher has an adjustable shaving knife located just back of the reciprocating cutter, which frees the plate from the metal chips which
Fig. 27.
become imbedded in the plate by passing under the spring roller, and which would otherwise have to be removed with a file or scraper. The shaver knife also removes the tool marks left by the rougher, and gives the plate a finished appearance.
122
ELECTROTYPING.
After the electrotype has been roughed it is taken back to the finishing block and carefully examined. Every minor defect is then remedied and necessary corrections made.
To more readily detect the low spots in the plate, the face of the electrotype is lightly rubbed over with a rubber ink eraser, mounted on a block of wood, or with a piece of fine emery paper stretched over a block. Those portions of the electrotype which do not receive a polish from this treatment are obviously low, and after locating them on the back of the plate with the aid of
Fig. 28.
ELECTROTYPING. 128
the calipers, they are hammered or punched up to a uniform level. After each operation of hammering or punching, the electrotype is planed down and straight- ened, and again tested with the rubber, and these treat- ments are repeated until all the dark spots have been brightened.
While the process of straightening an electrotype as thus described is very simple, it really calls for a high degree of mechanical skill, which can be acquired only by long practice.
The electrotype having been straightened and re- paired, it is taken to the shaving machine for a final cut, which should reduce its thickness, if a book plate, to exactly ii points (small pica), this thickness having been adopted by the electrotypers' associations of America as a national standard for bookwork. If the plate is to be mounted on a wooden base it may be shaved somewhat thinner.
Shaving machines are of various patterns and sizes, some operated by steam power and some by hand. The hand shaver consists of an iron table planed perfectly true upon its upper surface, and provided with a stop at one end to hold the plate in position. The side edges of the table are planed true, both top and bottom, and serve as guides for a sliding head to which the knife is bolted. Secured to the rear of the head and traversing the entire length of the machine are steel racks, one on either side, which are engaged by two pinions located on a shaft which is at right angles with the racks. To one end of the shaft a cast-iron spider is keyed, and to the spider long wooden spokes are bolted, which afford the means of operating the head. The head is provided
124
ELECTROTYPING.
with brass gibs, and the wear on the gibs may be taken up by means of set screws.
In large establishments shaving machines are usually driven by steam power. There are various devices for applying the power, one of which is illustrated in
Fig. 29,
Fig. 29. The shaft and pinions acting on the racks are the same as in the hand machine. A large gear wheel is substituted for the spoke wheel on the main shaft and is driven by a pinion to whose shaft power is communicated through intermediate gearing by means of band wheels shown at the left of the machine.
ELECTROTYPING.
125
Nearly all shaving machines are provided with a spring roller located in front of and attached by brack- ets to the head. The purpose of the roller is to press the plate flat down on the bed of the machine just before the knife begins its cut. A plate which is slightly uneven or warped is thus secured against the danger of ' ' go"gii^g> ' ' ^nd the necessity for planing or filing a bevel on the end of the plate is also obviated.
Another type of shaving machine has a bed resting on steel wedges which are made adjustable by a screw
Fig. 30
126 ELECTROTYPING.
passing through the front of the machine and terminat- ing in an indexed hand wheel. By means of this wheel the bed may be raised or lowered to any desired height within the range of the machine.
Fig. 30 illustrates a machine which is of compara- tively new design and differs in many respects from other makes. The following description is given by the manufacturer: "The knife remains stationary, the plate to be shaved being placed on a table and passed under the knife. Power is applied to move the table in one direction only, the power being thrown on and off by a lever handle, not shown, convenient to the right hand of the operator. The backward move- ment is obtained by means of a hand wheel. The table is extended beyond the head toward the front of the machine, affording increased bearing surface and equaliz- ing the wear over all parts of its length ; the extended portion, is made slightly concave, on which plates may be bent so that they shall rest properly on the shaving table. At the front of the machine, on the left side, is an inverted plane, by which the plates may be beveled as is usual to prevent the too abrupt commencement of the shaving operation. ' '
ELECTROTYPING.
127
CHAPTER XVII.
TRIMMING AND ROUTING.
ALL electrotype plates, whether job or book work, require to be trimmed on sides and ends. In the case of wood-mounted plates the trimming is done after they have been mounted on blocks, when plate and block may be finished at one operation. The cir- cular saw is unsuited for such work because of its tendency to spring away from the job, and because its cut is more or less ragged and uneven.
Fig. 31.
Various machines have been designed for the finish- ing of electrotypes, the simplest and least expensive of which is the shootboard, Fig. 31, which consists of an
128 ELECTROTYPING.
iron plate with a gutter or chute along one side in which a plane, furnished with an adjustable cutter blade, freely slides. A stop extending across the bed at right angles with the gutter serves as a rest for the electrotype and also as a guide for squaring the plate. The plane is
Fig. 32.
provided with two blades, one for making a square edge and one for producing a beveled edge such as is required on book plates.
Fig. 32 illustrates a very convenient and efficient trimming machine, specially designed for finishing type- high or ' ' body ' ' work. A rapidly rotating arbor carry- ing a cutter head, in which are secured two or more
ELECTROTYPING. * 129
cutting tools, is journaled in a substantial iron frame. The work is carried past the cutters on a reciprocating carriage which slides on ways parallel with the cutter head. The carriage is furnished with a right-angled adjustable gauge against which the work rests, which is adjusted by a finely threaded feed-screw, admitting of close and accurate work. The trimmer head should travel at a speed of about 3,500 revolutions per minute. To prevent the work from being drawn into the cutters and mangled it must be held securely on the carriage. Large and heavy pieces may be held by the fingers without danger, but the very small pieces, such as one, two or three line electrotypes, should be held by a lineholder, Fig. 33. The lineholder is an oblong
Fig. 33.
block of iron ten or twelve inches in length, two inches in width, and one inch high. A dove-tailed groove, extending the full length of the side face of the block, admits two thin serrated clamps, one of which is secured by means of a set screw at any desired distance from the end of the block, and the other is pivoted to the end of a lever which is operated by a handle on the top of the block. The under side of the block is recessed to receive a spiral spring which is attached to
130 ELECTROTYPING.
the lever and serves to hold the clamps firmly together upon the work. In operation the block is placed upon the carriage of the trimmer, the clamp jaws separated by means of the handle and the work inserted between them. On releasing the handle, the spring acting on the lever draws the clamps together. The work is thus securely held and may be trimmed without danger to the eyes or fingers of the operator, provided the line- holder itself be held firmly against the side gauge of the machine during the operation of trimming. It should be impressed upon the workman that whether trimming large or small pieces it is important that the carriage be kept free from chips. More accidents have been caused by carelessness in this regard than from all other causes combined. A chip or a small piece of metal under the work will cause it to chatter or rock when it encounters the cutters, with the result that the workman often loses control of it; and even if he is not injured by flying fragments his work will be destroyed.
Two kinds of cutters are used in trimming machines, one for trimming metal and the other for wood, or wood and metal combined, such as job or book plates mounted on cherry or mahogany blocks. The cutters should be made of Stubs' tool steel, hardened, and the temper drawn to a purple color. The holes in the cutter head are usually made round, in which case round steel of a size which will accurately fit the holes should be used for tools. The cutting ends of the metal cutters must be squared for at least a half inch back from the end — that is to say, there must be one right-angled corner to do the cutting. Fig. 34 is a side and end view of a
ELECTROTYPING.
131
metal cutter, and Fig. 35 illustrates a wood cutter or "goose-bill."
It sometimes becomes necessary to deepen the relief in an electrotype to prevent blacking or smutting the paper in printing. While this operation may be per-
FlG. 35.
formed with a mallet and chisel, it is always preferable to employ a router. Fig. 36. In this machine a rapidly revolving vertical spindle carries on its lower end a chuck in which may be secured cutting tools of various sizes suited to the nature of the work to be performed. The box in which the spindle turns is bolted to a handle- bar, one end of which serves as a handle for guiding the tool over the work, while the other end is pivoted to another handle-bar which is again pivoted to the frame of the machine. The double joints thus formed permit the tool to be moved freely in any direction over the bed of the machine. The second handle-bar is sup- ported at the elbow formed by pivoting together the two bars, by a steel segment, and the first handle-bar
132
ELECTROTYPING.
rests on a straightedge of hard wood extending the entire length of the machine. The ends of the hard- wood slide are supported by spring studs, which hold
Fig. 36.
the handle-bar carrying the spindle high enough from the table so that the cutting tool clears the work when not in operation. A pedal attached to a lever under- neath the machine affords a means of compressing the springs, thereby permitting the tool to enter the work.
ELECTROTYPING. 133
The tool spindle is adjustable in a vertical direction f:o provide for plates of different thicknesses, as when a change from type-high to plate work, or vice versa, is desired. This adjustment is obtained by means of a hand wheel attached to a threaded sleeve in which the spindle turns. The sleeve is provided with a feather to prevent its turning, so that a movement of the hand wheel in either direction raises or lowers the spindle. The work is held in screw clamps, which slide freely in dovetailed grooves planed in the bed of the machine. Power is transmitted to the tool spindle by a belt passing over idle pulleys at the corner of the machine. The pulleys at the pivotal points of the radial arms enable the operator to move the spindle freely in any direction without changing the tension of the belt. To perform smooth and rapid work router tools require to be driven at a high speed. For electrotype metal the speed should be about 12,000 revolutions per minute. A machine running so rapidly should, of course, receive careful attention. The bearings should be kept clean
Fig. 37.
and well oiled, and must not be permitted to become overheated. Router tools for general work are about the size of a lead pencil. For special work they may be made as small as one-sixteenth of an inch in diameter, and when large quantities of metal are to be removed, the size of the tool may be increased to one-half inch. The cutting end of the tool is made in
134
ELECTROTYPING.
the shape of a half moon, as shown in Fig. 37, the leading point being slightly longer than the heel, to pre- vent clogging. This tool is sharpened by grinding the end only, and may, therefore, be easily kept in order. Book plates, when finished ready for the press, are usually mounted on patent blocks, and are secured to
Fig. 38.
ELECTROTYPING. 135
their bases by bevel clamps which lap over the edges of the plates. It is, therefore, necessary to provide a bev- eled edge for the plates. This work may be performed on a shootboard by using a suitable plane; but when a large number of plates are to be prepared, it is cus- tomary to employ a beveling machine — Fig. 38. This machine resembles a trimmer, but has an adjustable vertical shaft. It has a reciprocating carriage to carry the work past the cutters, is provided with gauges for the alignment of the work, and may be adjusted so as to produce either a rabbet or bevel, as may be desired.
136 ELECTROTYPING.
CHAPTER XVIII.
REVISING.
AFTER book plates have been straightened, shaved . and beveled, a proof is taken, and it sometimes happens that errors or omissions are then discovered which make changes and corrections necessary. Such changes may consist in some cases of only a single let- ter, while in others an entire line or paragraph may be involved. In the former case, the defective letters are punched out and type inserted in their places, and in the latter, the line or paragraph is set up and electrotyped, and after cutting out the defective portion of the plate the new piece is set in and soldered. The special tools required for this work consist of a set of punches and chisels and a pair of calipers, such as have been pre- viously described; a revising stick (Fig. 39), a blow pipe, a pair of cutting pliers, a soldering iron, some small flat files, and a light hammer. A complete set of chisels and punches consists of eight sizes, and corresponds with the different sizes of type in general use, namely: pica, small pica, long primer, bourgeois, brevier, minion, nonpareil and agate. The thickness of the tools corre- sponds with that of the letter i in the respective fonts. The revising stick may be made of a piece of print- ers' brass rule, six or more inches in length. To one edge and one end of the rule a strip of brass one-eighth
ELECTROTYPING.
137
of an inch square should be soldered, as shown in Fig. 39. This makes a convenient, and in fact indispensable tool for holding a line of type while fitting it to the slot in the plate in which it is to be soldered.
Fig. 39.
A line gauge, Fig. 40, is employed for detecting errors of alignment between the inserted type and the remainder of the line, and is also employed for the alignment of newspaper headings or other jobs com- posed of capitals and lower-case letters. In trimming a line composed of a capital letter followed by several lower-case letters, the width of the block, of course,
Fig. 40.
must correspond with the width of the capital, and it is obvious that without a guide it would be difficult to trim the block so that the lower-case letters would all be at an equal distance from the top and bottom of the block. The same difficulty would occur in trimming
138
ELECTROTYPING.
any kind of a job requiring a margin above and below the matter. The Une gauge enables the operator to trim the edges of such jobs exactly parallel with the printing face, and is, therefore, an important and almost indispensable tool. When used in revising, the edge of the gauge is set in alignment with the line in which a correction is to be made. After the type has been inserted, and before it has been permanently secured by soldering, an application of the gauge will determine whether the alignment is perfect.
The blowpipe is used for soldering in places which cannot be conveniently reached with a soldering iron. It consists of a Y of brass tubing, one of whose arms is connected by a rubber tube with the gas supply. By blowing in the other arm of the Y a stream of air is mixed with the gas. The point of flame may be directed and focused on any desired point, however small.
Referring to Fig. 41, it will be observed that the cutting ends of the revising punches are provided with V grooves, which give to the tools two cutting edges,
Fig. 41.
thus admitting of a sharp, clean cut through the plate of just the size of the type which is to be inserted. In correcting a typographical error in a plate, the workman first marks with his caliper the exact location of the
ELECTROTYPING. 139
letter upon the back of the plate. With a small chisel a groove is then planed at the point marked by the caliper to the depth of about one-half the thickness of the plate, A punch of the proper size having been selected, the plate is turned over, face up, upon a block of wood, and with a sharp blow with the hammer the letter is punched out. Turning the plate over again, face down upon the finishing block, the type is inserted in the hole, and the contiguous metal crowded against it with a chisel until it is secured against dropping out, when the face is examined to see that the inserted type is in alignment with the remainder of the line and level with the surface of the plate. Care must also be observed to keep the type on its feet — that is to say, it must not lean from the perpendicular. The body of the type which has been left projecting through the hole is now cut off with the pliers level with the back of the plate, and the type secured in its position with a drop of solder. It is of course necessary to observe some care, otherwise there would be danger of melting the surrounding metal or the type itself After the type is secured the superfluous solder is removed with a chisel or file.
When several consecutive letters are to be mserted in the plate, the hole made with the punch is enlarged with chisel and file to the size of the correction, and the type which has been previously set up in the revising stick is inserted and temporarily secured as before. Somewhat more skill is required to make a correction of this kind than to insert a single letter, as the slot must be kept parallel and in exact alignment with the remainder of the line, and this is a more difficult matter
140 ELECTROTYPING.
than to punch a single hole in the plate. When the slot has been made too large, as sometimes occurs, the type is aligned by crowding the contiguous metal against that side of the type which is above or below the line. When the type has been properly placed it is usually partially secured by soldering before cutting off the body; otherwise there would be danger of dis- turbing it.
When the correction consists of several words or parts of lines, the matter is set up and electrotyped in the usual manner. The corrected piece so made is laid on the plate in the position it is to occupy, and with a graver or other sharp-pointed tool its exact outline is transferred to the plate. A hole is drilled in one corner and the defective portion of the plate cut out with a jig saw — Fig. 42. The correction is then inserted, the plate turned face down and a drop of solder applied to each of the four corners. During the operation of sol- dering, the plate and correction should be firmly held against the finishing block to prevent warping or spring- ing of the pieces, which might otherwise be caused by the heat of the iron. For this purpose the cutting pliers may be reversed, the end of one handle being used to hold the plate and the other the correction.
A necessary part of the equipment of an electrotype foundry is a set of brass standards based upon the print- er's universal unit of measurement, the pica. These standards should be twenty-six in number, ranging from one to twenty-six picas in length. The convenience of such standards will be apparent when it is remembered that all large type, such as is employed for newspaper headings, etc. , is made to occupy the space of a certain
ELECTROTYPING.
141
Fig. 42.
142 ELECTROTYPING.
number of lines of pica and is called 6-line type, 7-line type, etc.
In addition to the pica standards, the electrotyper should have a type-high standard, preferably made of steel, about 2 by 3 inches in size and .919 of an inch thick. Such a standard is useful not only for testing finished work, but also for setting the knife of the shav- ing machine, for which purpose it is placed on the bed of the shaver and the knife screwed down until it will just touch it.
Book plates are usually worked on patent blocks and should be shaved to exactly eleven points (small pica) in thickness. For testing this class of work a standard should also be provided.
ELECTROTYPING. 143
CHAPTER XIX.
BLOCKING.
"DOOK plates are usually worked on patent blocks, ^-^ with which every large publishing house is sup- plied. These blocks are made in some cases of wood, but preferably of iron, accurately finished and provided with clamping devices for securing the plate to the base. The best blocks are made in sections, and may be arranged and adjusted to fit various sizes of plates. The clamps are beveled and made adjustable so that they will fit snugly over the beveled edge of the plates.
Plates which cannot be worked on patent blocks are secured by screws, tacks or anchors to wooden blocks. Mahogany makes the best blocking wood, but is rather expensive for general work. Cherry comes next, and is the wood most generally employed for blocks ; birch and maple are also used to some extent. Blocking wood may be procured ready for use, kiln dried, and surfaced to proper thickness; but most electrotypers prefer to purchase lumber in the rough and dress it to thickness as it is required for blocking, thus avoiding danger of warping, which is likely to occur when the wood is dressed several days in advance of its use.
Lumber which has been thoroughly dried in the yard is superior to kiln dried lumber because it is less susceptible to changes of atmosphere. When sufficient space is available it is always advisable to carry a stock
144
ELECTROTYPING.
in the foundry, where it soon becomes seasoned. It often happens, however, that well-seasoned lumber can- not be procured and kiln drying then becomes neces- sary. By whatever process the wood is dried it should
Fig. 43-
be thoroughly done, otherwise the block will warp after the electrotype has been secured to it, probably after it has been delivered to the printer, in which case much annoyance and expense will inevitably result.
ELECTROTYPING. 145
Blocking wood must be surfaced on both sides and with perfect accuracy to insure good printing. For this purpose a rotary planer, Fig. 43, is almost indispensa- ble. The peculiar advantage of this machine consists in the fact that it dresses the wood perfectly flat and level, no matter how badly it may have been warped or sprung before planing. In this respect it is far supe- rior to the ordinary wood planer, for, while the wood is flattened by the pressure rollers during the operation of planing, it springs back to its original shape on being released.
Referring to Fig. 43, it will be observed that the cut- ting tools of the rotary planer are secured in a revolving disk which is made vertically adjustable by means of the crank shown at the top of the machine. Power is com- municated to the disk by a belt passing over idlers at the rear of the upright frame to the pulley on the disk shaft. One of these idlers is secured to a shaft which carries on its outer end a grooved pulley which provides a means of transmitting power to the worm shaft shown at the side of the machine. The worm wheel driven by this shaft is secured to a shaft passing under the travel- ing bed, and is provided on its inner end with a small pinion which engages the rack attached to the under side of the bed. By a simple mechanism which is at all times in control of the operator, the worm is thrown out of gear at the termination of the cut and the bed returned to its first position by hand. The lumber is held during the operation of planing between the jaws of two clamps, one of which is stationary and the other connected with a screw which terminates in the crank
handle shown at the front of the machine. In opera- 10
146 ELECTROTYPING.
tion, the board is placed between the jaws of the clamps and locked by means of the crank mentioned. The board is thus secured against springing or rocking while its upper surface is dressed perfectly true and level. The board is then turned over with its flat surface against the bed of the machine, and again passed under the cutters, which reduce it to the required thickness. The disk is raised and lowered by a graduated adjust- ing screw operated by the crank shown at the top of the machine, and may, therefore, always be returned to the proper height for the finishing cut without going to the trouble of comparing each board with a standard. Ow- ing to the large size of the disk and the fact that the tools are located near its periphery, the machine should be driven at a speed not exceeding 1,500 revolutions per minute.
After planing, the boards are cut into convenient lengths for handling, and the plates secured to them by means of wire brads or screws, or both. Brads may be driven through the thin places (spaces) in the plates, but for the screws holes should be drilled and countersunk in order that the heads may be sufficiently depressed to avoid danger of blacking or smutting in printing. Where a plate has no spaces or blanks where brads or screws may be driven, it is customary to "anchor" the plate to the block. For this purpose holes about one-fourth of an inch in diameter are bored through the block and deeply countersunk on both sides. If the plate has been finished long enough to have become oxidized, the back should be brightened by filing, and is then laid on the block and temporarily secured thereto by hand clamps. It is then turned over
ELECTROTYPING. 147
on its face, and, after a very small quantity of soldering fluid has been applied to the plate through the holes, melted solder is poured in until the holes are full. It is important, of course, not to get the solder too hot, as in that case there would be danger of its melting through the plate. There is always an element of uncertainty in securing electrotypes to blocks by this method, and, when possible, it is best as an additional safeguard to rabbet the edges of the plate and drive in a few brads. When the plate is small, it may some- times be fastened securely in this way without the use of anchors.
When several small cuts are to be blocked at one time, it is customary to tack them on to a board as large as may be conveniently planed, leaving sufficient room between the cuts to saw them apart. Should it be necessary to take a final shaving off the bottom of the cuts after they have been blocked, it may be done more economically if several are shaved at a time than if each one were to be handled separately.
Very large blocks are liable to warp in time, in spite of any precautions which may be taken to prevent it, and to reduce this tendency to a minimum each block should be strengthened by end strips crossing the grain of the block. The strips may be secured to the blocks by countersunk screws, but a more satisfactory method is to dovetail them together. A machine specially designed for this work is illustrated in Fig. 44. The cutting tools are a thick gouge saw of about No. 3 gauge, which cuts a slot in the board or strip, and a vertical revolving cutter, which follows in the slot and changes it into a dovetail groove. The mechanism for
148
ELECTROTYPING.
driving the tools is sufficiently explained by the engrav- ing. The parallel side gauge, against which the board is pressed during the cutting of the dovetail, can be instantly changed by means of the small lever at the
Fig. 44.
ELECTROTYPING. 149
right of the machine so that either the center or the edge of the strip may be thrown in alignment with the cutters, thus providing a means of cutting a dovetail in one board and a tenon on the other. The mechanism for changing the side gauge from one position to the other is such that there can be no variation in the dis- tance it is moved, and whatever position it occupies it is automatically locked therein, thus insuring absolute uniformity of work. The machine may be readily adjusted to operate on lumber of different thicknesses.
150 ELECTROTYPING,
CHAPTER XX. DR. Albert's metal molds.
THE subject of metal molds is one in which all progressive electrotypers are interested, and we have therefore translated from the German Dr. Albert's description of his process, which is sufficiently in detail to enable the skilled electrotyper to compre- hend how it is possible to mold in lead. Dr. Albert does not explain the nature of the mechanism by which he is able to obtain " successive partial pressures " on " any press," nor does he describe fully the character of the alloy which he employs in loosening the shell from the matrix. The American patents concerning Dr. Albert's process have been purchased by an Ameri- can manufacturer of electrotyping machinery, who has already installed several plants in this country which are in more or less successful operation. The follow- ing is a translation from " Theory and Practice of the Metal Matrix," by Dr. E. Albert :
" Jacobi, the inventor of the art of electrotyping, has for more than half a century experimented in pro- ducing lead matrices for engraved steel and copper plates, and with the greatest success. Nevertheless, the wax and gutta-percha matrix has been the popular method of electrotyping until recently, although the defects of the electrotypes made from it urgently called for a change in the method.
ELECTROTYPING. 151
" The origin of these defects is to be found princi- pally in the fact that the non-conducting material must first be made conductive by brushing with black lead, whereby it is impossible to avoid an essential deterio- ration in quality as compared with the original ; and that in consequence of the necessary heating of the material before the impression is taken, and the changes in its dimensions after cooling, an exact regis- ter of electrotypes for multi-colored prints can not be guaranteed. With the possibility of using conducting and cold-molded metal matrices, all this inferiority of the electrotypes, as compared with the original, is at once removed.
" But modern printing forms, such as photoengra- vings, woodcuts, type forms, heliogravure, can not be impressed in soft metal in the same manner as in wax and gutta-percha. The requisite pressure would be so great that the soft printing material would be destroyed.
" Some attempts to avoid the high pressure in pro- ducing metal matrices by using very thin lead foils and putting on them layers of thoroughly saturated pasteboard, or wax, have never had any practical results, although they date back to the forties in the last century, and for the following reasons :
" Every electrotyper knows that in molding from mixed type and cut forms the type is impressed long before the shading of the woodcut or a photoengraving is molded. The above-mentioned thoroughly satu- rated pasteboard affects the impression just as wax or gutta-percha made soft by heating, i. e., the lead foil must first be pressed into the large and then into the
152 RLECTROTYPING.
smallest depressions of the printing form by the satu- rated pasteboard. In spite of the enormous ductility of lead, it will not, of course, satisfy this demand for expansion.
" It must be considered that in the square milli- meter of a photoengraving there are thirty-six depres- sions into which the lead foil must be pressed, and that it applies itself to 144 side walls per qmm. In underetched printing-plates considerable force is nec- essary to separate the matrix from the plate, and, therefore, it is impossible in larger forms, ""without dis- torting the mold, to separate the plate from the lead foil, which, in the interest of lessening the pressure, must be very thin.
" The pressure necessary for forcing any molding material into the smallest depressions of a form can not be produced as long as an opportunity remains for it to make its way into open spaces. In consequence of this characteristic, all wax matrices must be sub- jected to a shaving process to remove the large angu- lar protuberances, which correspond to the depressions in the printing form. This necessary manipulation would, of course, be impossible in matrices consisting of thin lead foil, and also for these reasons the use of this method for rule etching, woodcuts and type mat- ter is excluded.
" It has been pointed out as a characteristic of the materials hitherto used for the production of matrices that the molding of the largest depressions is done before that of the smallest. With soft metals, espe- cially lead, the contrary is the case, as this material first shifts in the direction of the pressure and fills the
ELECTROTYPING. 153
small depressions. With increased pressure, which is necessary in order also to press the lead down in the large depressions of the form, the lead also begins to shift like wax to the sides in the neighborhood of the first-molded parts.
"Apart from the fact that the already molded little points, which correspond to the smallest depressions in the form, will be shaved off, this shifting of the lead has another disadvantage, namely, that the lead lodges in these smallest depressions and the original will be made unfit for use through this filling up with lead. Besides, neither type matter nor cuts will withstand the enormous pressure that must be used to impress a lead plate of at least five millimeters (about one-fifth of an inch) thickness into the large depressions.
" But such a thickness in the lead plate would be just as necessary as in the wax or gutta-percha, as the difference in height between the face of the type and that of the spacing is about one pica.
" With the present means, therefore, matrices can not be produced in metal plates, and it has been neces- sary to use wax or gutta-percha for this purpose, until, in the year 1903, Dr. Albert succeeded in establishing a method for the rational production of metal matrices. This method is based on a number of inventions and is patented in all civilized countries.
" The knowledge that depressions in the electro- types in the blank spaces are required only to prevent smearing in the subsequent printing of the electro- types, led to the course of pressing or bending a lead plate of about two millimeters (about seventy-eight one-thousandths of an inch) thickness into said depres-
154
ELECTROTYPING.
sions only so far as the technical necessities of printing demanded, by means of a backlayer of some soft material.
" This method is accordingly based upon a com- bination of impression and bending. The bending of the lead will be greater the larger and wider the depressed surface is, and the blank places will there- fore be of such a depth that they will not smear in printing. The process is illustrated by Figs, i and 2.
" Fig. I shows the arrangement of the press platen, the lead plate and the soft, elastic intermediate layer
Fig. I.
before the impression is taken. The material used for this purpose must originally, or in its arrangement, be of certain qualities, and must be softer than the mold- ing material. It must be compressible without giving way sideward under the pressure ; but it must also give a certain resistance to the compression in order to be able by this power of resistance to bend the lead plate where it lies over the hollow. This material, however, should not be so soft as, for example, heated wax, but should be porously soft, either in its nature or in its arrangement. A certain degree of elasticity is useful in the interest of the bending of the molding plate into the depressions in the form.
ELECTROTYPING,
155
" Such intermediate layer can suitably consist of a number of layers of paper, and such a one is, through the nature of the fiber of the paper, as well as through the air inclosed between, soft and elastic in itself in respect to the vertical direction toward the surface of impression ; while, on the other hand, through the texture of the paper, the necessary check will be given to prevent the paper from gliding sideways at the beginning of the pressure. In earlier experiments the latter tendency was prevented by saturating the paper.
" In Fig. 2 the platen is lowered so that the inter- mediate layer between the points o o', from which the first counterpressure comes, is compressed to half its original volume. In the moment when, through com-
FlG. 2.
pression, the intermediate layer has reached the same degree of hardness as the molding material, the next, increase in pressure will press this material into the smallest depressions of the surface o o'. The lead lying perfectly free between the points u u', and there- fore exerting no counterpressure, will simultaneously be pressed down in the hollow space u u' as an effect of the resisting power of the intermediate layer.
" The same will be the case between the points m m', although in a lesser degree, just as a board that
156 ELECTROTYPING.
is supported at intervals of two meters will sag more than one whose supports are only one meter apart, with the same weight on it.
" By the use of this bending i)rocess, the requisite molding pressure is reduced to one-tenth of what would otherwise be necessary, and the use of metal molds is made possible.
" The question of producing the metal matrix was thus solved only for moderate sizes, for, even if the pressure was considerably lessened by the correct selec- tion of the thickness of the lead plate and by the back- layer of a soft, elastic matter, still an essentially greater pressure than is required for wax or gutta-percha is necessary. The usual hydraulic presses with about one hundred atmospheres were consequently not usable for the impression of larger sizes.
" By using a successive partial pressure and at the same time introducing a secondary pressure, Dr. Albert has succeeded in changing any press to a twenty times higher capacity at very small cost. This gradual progress of a limited pressure over the whole form affords an opportunity for the air to escape and pre- vents troubles arising from this cause. As the shifting proceeds automatically, there is no loss of time worth mentioning in this method. For example : The mold- ing of a form of Woche (the Week) requires only a period of fifty-five seconds, and for a form of Berliner Illustrirte Zeitting (Berlin Illustrated Gazette) not quite two minutes. For molding of cut forms of the same size only half of the time mentioned is required. With this method there is no difficulty whatever in producing molds of any size.
ELECTROTYPING. 157
" It is self-evident that a copper shell deposited on a lead matrix can not be loosened directly, as is the case with a wax matrix. It would not be possible to melt the lead away from the copper without injury to the electrotype. But by letting the matrix and copper deposit float on a very easily fusible metal alloy with many free calorics, this loosening succeeds so well that the same matrix can be used five times for the produc- tion of new electrotypes without affecting the quality of the electrotypes. Thus the problem of the metal matrix is perfectly solved in all respects.
" These inventions have made a revolution in elec- trotyping technics. The word revolution, however, has more reference to the clearness, rapidity, cheapness and quality of the production than to the change of the working methods and arrangements of already established electrotype foundries.
"Of great importance is the discarding or doing away with the blackleading of the mold matrix, whereby in soft printing elements of photoengravings, etc., a shifting of the tone values in respect to the original occurs. The metal matrix in itself conducts the electricity and needs no blackleading.
" The Albert electrotype is identical with the origi- nal. A difference in the print of both can not be detected. This identity of the Albert electrotype and the original, in respect to the tone values, is based on the nature of the metal matrix and is not dependent on the skill of the workman.
" The molding process itself can be done on any hydraulic press in use. The machinery for successive partial pressure can be set up in a few hours at a small
158 ELECTROTYPING.
expense. The increase of the capacity of the press is enormous ; with 120 atmospheres (1,800 pounds to the square inch), with 40 centimeters piston diameter (about 16 inches) photoengravings, 40 by 50 centi- meters ( 16 by 20 inches) large, can be molded. Faulty moldings, as in wax, which are occasioned by inclosed air, do not generally occur, as the air always has a chance to escape during the successive partial pressure.
" It has already been mentioned how little time is necessary for successive partial pressure when suitable arrangements are made. Wax and gutta-percha have not only to be blackleaded after molding, but by heat- ing be brought to a certain degree of softness before molding. In this way changes in the dimensions arise when the molds cool off, and exact register can there- fore not be guaranteed in electrotypes for multi- colored prints. The metal matrix is perfectly cold- molded, and therefore an exact register in multi- colored prints is always assured.
" Thus the metal matrix is cleaner and more rapid than wax or gutta-percha, and, besides, is of a quality that guarantees the identity of the electrotypes with the original. The financial advantages of the Albert electrotype will be seen in the further manipulation of the matrix.
"After the lifting off of the form, the matrix will, without any afterwork whatever, be fastened with four nails to a board, whose suspending bow touches the matrix by contact, and the latter will at once be coated over the whole surface with copper in the same moment it is suspended in the bath. Owing to the high melting-point of the matrix, the copper bath can,
ELECTROTYPING. 159
without any danger to the matrix, be heated to 50° to 60° Celsius (which will allow an increase in the cur- rent tension of eight to twelve volts), and the forma- tion of a sufficiently thick copper deposit will follow in a hitherto-considered impossible short time ; for medium sizes only one-half to one hour for producing the deposit is needed.
" Besides this shortening of the time for producing the deposit, the high temperature will act favorably on the physical character of the electrically deposited copper, as well in respect to its hardness as to its elas- ticity, which also is evident in the fact that the electro- types need only a minimum straightening.
" The loosening of the copper shell from the metal matrix is done so easily, rapidly and surely that no damage to or change in the metal matrix or copper shell results. The matrix can therefore at once be suspended in the bath again for a second copper deposit, and this second electrotype, as well as the third and fourth, is in no way inferior to the first elec- trotype.
" When the matrix is not to be used any more, it can be converted into backing metal. The loosened copper shell can, of course, be backed in any way desirable, and the electrotype be made ready for print in the usual way. Only one hour and a half is needed (inclusive of the molding and copper deposit) for put- ting the electrotype in shape for the press."
REFERENCE LIST
OF TERMS, PROCESSES AN-D APPARATUS.
ACID, TO ASCERTAIN PERCENTAGE OF, IN SOLUTION. — Dilute lo grams of the solution with an equal quantity of distilled water. Add normal soda solution until Congo paper is no longer colored blue. The number of grams of soda solution consumed multiplied by 4.9 gives the number of grams of acid per liter. One liter equals 1,000 grams.
ACID, EFFECT OF, ON NICKEL BATH.— The pres- ence of a small quantity of free acid in the nickel bath effects the reduction of a whiter nickel than in the case with a neutral or alkaline solution. Hence a slightly acid reaction of the bath due to the presence of citric acid, with the exclusion of the strong acids of the metalloids, can be highly recommended. The quantity of free acid must, however, not be too large, as this would cause the deposit to pull off.
ACID, EFFECT OF, IN SOLUTION.— According to Von Hubl, the minimum current density per square foot of cathode in a fifteen per cent blue vitriol solution without acidu- lation is 24.1 amperes, while the same solution with six per cent sulphuric acid added required but 13.9 amperes.
ACID, HYDROCHLORIC— The pure acid is a colorless fluid which emits abundant fumes in contact with the air and has a pungent odor by which it is readily distinguished from other acids. The specific gravity of the strongest hydrochloric acid is 1.2; the crude acid of commerce has a ycllowi.sh color, due to iron, and contains arsenic.
ACID, MURIATIC— See hydrochloric acid.
ACID, SULPHURIC— Ordinary sulphuric acid has a spe- cific gravity of 1.84. It is used in the preparation of the
11 161
162 ELECTROTYPING.
depositing solution. In diluting the acid with water, it should in all cases be added to the water in a gentle stream and with constant stirring, as otherwise a dangerous explosion might result. While it is known that sulphuric acid aids in making the bath conductive, there is, of course, a limit to the quantity which may be advantageously employed, and it is doubtful if this point has ever been exactly determined. The writer has been to some trouble to ascertain the views of certain practical electrotypers on the subject and compared them with the recommendations of numerous scientific writers. From these various sources of information we learn that the solution of copper should show a specific gravity of from 14° to 18° B., and that to the solution should be added sulphuric acid in suf- ficient quantity to increase the density of the mixture from J4° to 9°. This wide divergence of opinion is probably due in some cases to the effort of the electrotyper to adapt his solu- tion to the current strength which his dynamo may happen to be generating.
ACID, SOLDERING. — Prepared by dissolving scrap zinc in hydrochloric acid (muriatic acid) to saturation, and adding from 25 to 50 per cent of water. The operation should be con- ducted in the open air, as the fumes produced are both dis- agreeable and dangerous.
AGITATION, BENEFITS OF.— The continuous agita- tion of the copper bath is of great advantage to the electro- type, particularly when rapid deposition is desired. The copper is more evenly deposited and of better quality, the formation of gas bubbles, nodules and excrescences is largely prevented, while the annoying streaks which sometimes appear on the deposit, usually as a result of an excess of metal in the solu- tion, are seldom or never seen in an agitated bath. But the principal advantage may be found in the fact that much higher current densities may be utilized, resulting in a corresponding increased rate of deposition.
AGITATION, DOES IT ELIMINATE RESISTANCE? — While agitation is a practical and useful aid to deposition of metals, and is recognized as such by all electrotypers who have
ELECTROTYPING. 163
given it a trial, as well as by all the great copper refiners of Europe and America, its chief value consists in the fact that it promotes uniformity in the composition of the solution, aids in the diffusion of metal in the solution, and, when a strong current is employed, prevents to a certain extent the forma- tion of nodules, excrescences and streaks on the cathode. It also minimizes the tendency to polarization and promotes purity in the character of the copper deposited. If inequality in the composition of the solution tends to increase the resist- ance of the solution, then agitation, by promoting uniformity, would diminish the resistance to just that extent. It is doubt- ful, however, whether the mere fact of giving motion to a solution adds to its conductivity. In other words, if an agi- tator should be introduced into a depositing solution which had previously been employed for electrotyping without agita- tion, and if no change were made in the content of acid or metal in the solution or in the speed of the dynamo, the increase in the rate of deposition would probably be inappre- ciable. It should be understood that some motion always takes place in the solution whenever deposition is going on. With- out motion there could be no diffusion, and without diffusion there could be no deposition, for it is obvious that there must be constant renewal of metal in the solution next the cathode, as otherwise it would soon become exhausted. This motion is caused by the sinking of the heavy liquid next the anode and the constant rising of the liquid next the cathode, where it is deprived of its metal, and consequently becomes lighter than the surrounding liquid. This motion, together with the stirring of the solution occasioned by the immersion and removal of the cathodes, is sufficient for the diffusion of the metal when a current of low density is employed. It is true that a solution undisturbed for some time will become more acid at the top than at the bottom and, therefore, more con- ductive at the top than at the bottom. Yet it is doubtful if the total resistance of the solution is very much affected by this condition. Granting that agitation would diminish the resistance of the solution to a slight extent by promoting uni-
164 ELECTROTYPING.
formity, it is certain that it does not influence the resistance beyond this point, for frequent tests have demonstrated that the current strength measured at the electrodes remains unchanged whether the agitator be in operation or not. But if the agitator does not in itself increase the rate of deposition, it enables the operator to increase his current and thereby accomplish practically the same purpose. Von Hubl found by careful laboratory tests that the current strength could be increased about fifty per cent when the bath is kept in gentle motion. This statement is very conservative and probably means that the current strength may be increased fifty per cent without changing the character of the copper or causing waste of power by polarization. If no consideration be given to economical working, there is no doubt but the current may be increased far beyond the fifty-seven amperes per square foot which he gives as a maximum.
AGITATION, METHODS OF.— One of the main objects of agitation is to remove the exhausted stratum of solution next to the cathode and replace it with a saturated solution in order that deposition may proceed with the greatest possible rapidity. Various mechanical means are employed to effect this object. The most popular method is that of forcing air through the solution from perforated lead or rubber pipes laid on the bottom of the vats. Another method consists in pump- ing the solution from the bottom of one end of the vat and discharging it in such a manner as to create a circular motion. Another method consists in mounting the anodes on spindles and revolving them slowly in the solution between the cathodes. By another and very effective method a horizontal rod is made to travel up and down between the anode and cathode. The latest and, it is claimed, the best method is briefly described as follows : A large perpendicular cylinder is made to revolve slowly in the solution. The cylinder is surrounded by anodes and to the periphery of the cylinder the cathodes arc attached. In operation the cathodes are constantly passing the anodes and the disturbance is so effectual that 200 or more amperes per square foot may be utilized without burning the deposit.
ELECTROTYPING. 165
ALKALINITY AND ACIDITY.— An excess of acid or alkali in a nickel solution may be instantly detected by dip- ping simultaneously into the solution strips of blue and red litmus paper. If the blue litmus paper becomes red, it indi- cates an excess of acid, while on the other hand the test shows that when red litmus paper becomes blue an excess of alkali is indicated.
ALLOY, FUSIBLE.— Melt i pound of lead in a clean vessel, and stir in % pound of tin and, finally, iJ/S pounds of bismuth. Stir well, and thoroughly incorporate the mixture; pour out gradually into water ; collect, and repeat until a com- plete admixture is obtained. It melts at 212° F., the tem- perature of boiling water.
AMALGAMATION OF ZINC— To amalgamate zinc plates it is necessary, first, if the plates be new, to wash them in hot caustic soda solution, so as to remove the greasy film imparted to them at the rolling mills. A flat vessel is then partially filled with dilute sulphuric acid and upon it is also poured a little of the best quality of mercury procurable. The plate is dipped in the liquid and the mercury rubbed on with a pad of tow or other suitable substance. The workman should take particular care to cover every portion of the surface. When the plates present a uniform silvery appearance they may be set upon edge to drain, after which they are ready to be placed in the battery.
AMMETER? WHAT IS AN.— Without going into technicalities, it may be said that the ammeter is an instru- ment for measuring the amount or quantity of electric current employed in performing work. The ammeter measures quan- tity, while the voltmeter measures pressure, and the product of quantity multiplied by pressure, as measured by these instru- ments, is called watts and is what we who buy electric power have to pay for at the end of each