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MONTHLY REVIEW

Published by the American Electroplaters Society
Publication and Editorial Office 3040 Diversey Ave., Chicago

VOL. XIV DECEMBER, 1927 No. 12


DECEMBER EDITORIAL
The month of Xmas greetings, and incidentally, inventorying of our factories; so why not, while in spirit of good cheer, examine ourselves or take inventory?

Have we used and gained any good from our associations in the society? If so, what are they; and if not, why not? Are we latent or have we neglected to try the many new things proposed, or have we just let it ride to await some ambitious member’s report to suddenly find our employer calling for efforts on the very things “we let go by” ?

Why not try and be Santa Claus yourselves ? Tell the industry 5 some of the things you have encountered during the year. If nothing you have discovered, some results trying the other fellow’s | offerings, not with ridicule or sarcasm, but instructive investigation. You will receive two pence for one expended this way and be glad on Xmas Day.

The Supreme Society and Editorial Staff wish you all a Merry Xmas and a Happy New Year and hope that our offerings may please you more in 1928.


CLEANERS AND CLEANING*

By Harry C. Bernard, Oakite Products, Inc.

*Read before American Electro-Platers Society, Fifteenth Annual Convention, Toledo, Ohio, Thursday, June 30th, 1927.


Progress in cleaning of metals before plating has been perhaps as great as progress in the plating processes themselves, although little recognition is usually taken of the fact. Many of you will recall the time when the scrubbing brush, the whiting box and the old-fashioned lye kettle were found in every plating shop. They were the instruments relied upon early in the history of the electroplating industry when cleaning was looked upon as a necessary evil instead of one of the essential steps in production deserving as careful consideration as preliminary manufacturing operations and subsequent plating and finishing operations.

When plating was done on a small scale, the scrubbing brush was fast enough. Lye and soda kettles were a slight improvement, but the concentrated solutions required to produce results often had to be supplemented by the scrubbing brush. The corrosive action of such solutions and of their vapors were a source of constant danger to the plater and his apprentices.

Contrast these conditions with the modern plating shops and plating departments of modern manufacturing plants. Speed, safety and healthful working conditions are required in cleaning operations as well as other manufacturing operations. Modern continuous cleaning and plating equipment demands speed and thoroughness in the cleaning operation in order to keep it operating at the maximum production for which it is designed. There is no opportunity for inspecting work and recleaning it if necessary. The cleaning must be thoroughly done as well as quickly done. Stripping and replating of rejects caused by imperfect cleaning cannot and will not be tolerated. Imagine, if you can, old-fashioned cleaning methods trying to keep pace with modern production methods.

Modern methods and materials for cleaning, which are so essential in large scale production, are also fortunately applicable on a smaller scale to the thousand medium and small-sized plating rooms in which much of the country’s electroplating is done. Modern cleaning materials specially prepared on the basis of sound practical experience make it possible to make up cleaning baths which begin to produce perfect cleaning promptly and efficiently. Modern production methods prohibit the old-fashioned practice of “working in” the freshly prepared cleaning bath.

Cleaning problems are not the same today as they were early in the history of electroplating. There are several developments in modern manufacturing practice which are particularly worthy of notice because of the effect which they have had in making crude alkali ineffective, unsuitable and obsolete as cleaning materials.

The development of die casting processes and die casting alloys with zinc or aluminum as the base has made it necessary to develop cleaning materials which will not dull the polished surface in the time required for cleaning. Alkalis have a pronounced solvent action on both zinc and aluminum, and alloys containing either of these metals cannot be subjected to such solutions long enough to assure thorough removal of the polishing materials. The problem is complicated to a large extent by modern polishing room practice. Greater speed in polishing operations is demanded and liberal use is made of polishing compounds to turn out increased production often on a piece work rate. This results in work being sent to the plating department with heavy and irregular deposits of polishing materials, which must be removed by the cleaning solutions. High speed production has brought about increased use of cold rolled steel for stampings to be plated without preliminary polishing. Mineral oils used in rolling the steel and in protecting the bright surface from rusting contain no saponifiable matter. Alkali which depend on their saponifying action for their effectiveness are unsuitable for this class of work. It is necessary to employ more rapid and more effective agents that will emulsify the mineral oils and destroy their adhesiveness to the metal. The fact that the mineral oil has been applied to the steel before subjecting it to the intense pressure and polishing action of the finishing rolls makes the problem of removing it an especially difficult one for even the most efficient of emulsifying agents.

Much investigation and research has been devoted in industry in the past few years to the development of standard or specified formulas for cleaning materials. Much creditable information on this subject has been presented in papers read before this and other associations. It is extremely interesting to note the importance which is attached to the formula for preparing a cleaner. The significant point is that in no instance do we find recommendations for the use of old-fashioned, crude alkalis in highly concentrated solutions. The impression is often created that with the proper formula the cleaning problem will be solved. Efforts to develop standard formulas which will handle the general run of cleaning operations in an industrial plant have, however, not met with unqualified success, and we believe that it is impossible to produce a formula which will give satisfactory performance under the extremely varying condition of cleaning operations to which it is applied.

Recognition should be taken of the fact that the formula alone is not the entire solution of the problem. Operating conditions and technique can be as important as the formula itself. No matter how efficient the cleaning material itself may be, it is very apt to fail in one or more of several important respects if the conditions under which it is used are unfavorable. Too little attention is, as a rule, devoted to the operating conditions under which cleaners are used to enable them to produce consistently uniform and satisfactory results. Constant supervision is required for the cleaning baths and cleaning operations as well as for the plating baths and plating operations in order to assure satisfactory performance.

Whether a plating room is using a cleaner prepared according to its own particular formula or a specially prepared cleaner that depends for its effectiveness upon its saponifying action, its emulsifying action or its colloidal action makes little difference when the cleaner fails to function properly. To get the cleaning operation back to its usual standard of efficiency becomes a practical problem and it is of little avail to call upon the colloids, the emulsifying agents or the hydroxyl ions for assistance. The principle under which the cleaning bath is operating is of no significance when it ceases to operate satisfactorily. When the bath has been prepared strictly according to the formula, there can be no question about the fact that failure to secure satisfactory results is due to some unintentional variation in the operating conditions. Once a suitable formula or cleaner has been found the satisfactory operation on a production basis is therefore clearly a matter of keeping the operating conditions at the point of highest efficiency in order to secure maximum service from the chemicals which are being used.

Equipment should be kept in first-class shape. An open and steam line discharging into a solution in order to heat it will easily overflow from 25 to 30% of the solution per day and more, providing condensation accumulates in the steam line. Equally efficient heating can be secured by providing a steam coil so that condensed steam will be discharged into the tank of hot rinse water. Of course, heating by steam coils is the usual practice, but very often a leak sufficient to discharge a large amount of contamination into the solution will develop and remain unnoticed for long periods of time unless the coils are put under pressure and tested every time the tank is cleaned out to make up a fresh solution.

The temperature of the cleaning bath plays a very important part not only in thoroughness, but speed of cleaning. Very often the plating room is compelled to struggle along with insufficient steam to properly heat the solutions which means slower cleaning, reduced production from the cleaning baths in use, increased rejects due to imperfect cleaning and increased consumption of chemicals because higher concentrations of the cleaning bath are required at the lower temperature. Where steam is supplied from a power boiler the average cost is about 40c per thousand pounds and the small additional amount required to insure proper heating is cheap compared with the cost of additional chemicals and other unsatisfactory operating conditions which result from the lack of sufficient heat.

In order to keep the cleaning bath operating properly, it is also important to reach a definite conclusion regarding the amount of material that must be added per day or per week under normal production. While chemical tests which indicate the total alkalinity of the bath are used in a few instances with very satisfactory results, it is preferable to determine the minimum amount of material required to maintain the bath at its proper strength and add this quantity of material at regular intervals. The tendency to blame the formula for slow or imperfect cleaning often results in the addition of excessive amounts of material in an attempt to produce results when the condition might easily have been corrected by the use of more heat. Too concentrated a solution will often fail to clean properly and maintain the required production. When it is found that cleaning material has been added in such an amount as to produce a saturated solution, diluting the solution with water will often restore the bath to its former efficiency.

The use of electric current for cleaning is, of course, a valuable aid where the current supply is available in a sufficient quantity so that advantage can be taken of it. It will often be found, however, that plating shops are equipped with a generator that is not more than sufficient to provide the current necessary for their plating baths, particularly in growing shops where new plating tanks are being installed from time to time without increasing the current supply. While to the well-informed plater the proper method of applying electric current for cleaning operations is well understood both in theory and practice, it is quite surprising to note the number of cases in which the process is not understood. This applies, of course, primarily to the numerous small shops which, however, constitute a great part of the electroplating industry and which, of course, can profit most by the type of service rendered by the American Electro-Platers’ Association. Most formulas will work well when assisted by electric current. In order to properly judge the efficiency of the formulas, its action in a still bath should be used as the basis, as under that condition it is the action of the solution itself that is being tested and not the effects produced by decomposition of the water through the use of electric current. Providing the cleaning solution has the necessary conductivity, it is perfectly obvious that the bath which is most effective without current will be most effective when current is used with it.

The foregoing are some of the variable factors which are presented which affect practically every cleaning problem. In addition to these there are factors such as the kind of metal, the kind of oil, grease, polishing compound or buffing compounds to be removed, the time permissible for cleaning as determined by the equipment at hand are conditions which cannot be altered without changing the problem itself. The formula which is used will necessarily have to fit in with these factors. Each individual shop presents a problem which is slightly different from every other shop. While research with a view of developing standard practices is desirable in cleaning as well as in plating operations, the factors which affect the cleaning operations are so extremely varied that any standardized formula and procedure would rarely conform with the conditions found in actual practice. For instance, a formula for an extremely satisfactory cleaner to remove emery cake from steel might be developed. There are, however, a number of different kinds of emery cake on the market and in some cases each manufacturer produces several grades, the grease content of some of which is easy to remove while that of others is more difficult to remove. Briefly, in order to standardize cleaning operations, it would first be necessary to standardize the various types of lubricating agents, polishing agents and buffing agents, which must be removed. Such standardization is, of course, entirely out of the question as its effect would be to destroy the individual initiative of manufacturers who are constantly endeavoring to make improvements in the products which they supply to the electroplating trade. Proper credit should be given to the supply manufacturers for the contribution which they have made to the development of the electroplating industry by exerting their efforts to provide machinery, supplies and chemicals to meet the constantly growing demand for greater production at reduced cost.

We have intentionally avoided any discussion of the theoretical aspects of cleaners and cleaning, and devoted our attention to the practical aspects of the problem. The operating conditions are practically always as important as the formula itself in determining the results which are secured from it. Some time, however, in the life of every formula it is certain to meet a critical test and to be seriously questioned and doubted as to its value. Perhaps it is not unusual that tile formula should be the first of a number of factors to be questioned, but such is usually the case even when the formula is absolutely not at fault in any respect. It is well when definitely deciding on a formula or cleaner that meets the requirements of the cleaning operation consistently for a period of time to place entire faith in its reliability and when failure occurs unexpectedly, to look elsewhere for the cause as in nine cases out of ten it will be found somewhere in the operating conditions.

As an instance of how far removed the actual cause of the trouble can be from the cleaning bath, we should like to cite the instance of a plant engaged in the nickel plating of brass safety razors. After a number of different cleaners and formulas had been tried out for removing the heavy tripoli deposits one was found which gave excellent results. Rejects due to imperfect cleaning were practically unknown. The cleaning baths operated without changing for much longer periods than it had ever been possible to operate them before. In the construction of these razors the blade retainer is held down by means of a flat brass spring. The hinge is formed by a lug on each side of the frame which projects through an eyelet stamped in the side of the blade retainer. One day it was discovered that the flat brass spring did not have sufficient tension to snap the blade retainer down after plating had been completed. When razors were tested before plating the same condition was found. When they were cleaned with a solvent such as gasoline the spring functioned perfectly. The condition had not been observed before but it was perfectly obvious to the inspectors that it had never been sufficiently pronounced to be noticeable until then: Serious doubt was cast upon the cleaning bath as being responsible for the apparent loss in tension of the springs. The plating room foreman, however, possessed sufficient confidence in his cleaning baths and a firm belief that such an action could not possibly be charged to any cleaning solution. Because of the excellent results which were being secured as far as the cleaning itself was concerned, he was reluctant to make a change without further investigation.

All of the different factors which might produce the effect were taken into consideration. The solution of the difficulty was finally found with the aid of the microscope. Because the spring action was satisfactory before cleaning, but not after, the possibility of increased friction at the hinge was investigated. It was found that oiling the pivots on which the blade retainer turned would restore the action of the spring to normal. Further examination showed that all of the lugs on razors which did not show proper spring action after cleaning had a decided burr which created sufficient additional friction to prevent the spring from acting when the greasy material present had been completely removed by the cleaning bath. The solution of the problem was therefore found in the tool room, where changes were made so as to eliminate this burr which was being produced because of wear on the dies through continuous use. Without sufficient faith in his formula it is obvious that this plating room foreman might have gone through another long and futile search to find a formula that would clean his parts perfectly, and also overcome the trouble with the springs which would have continued until the worn dies were replaced. By a careful and intelligent study of the problem he was not only able to adhere to the formula, but also show how to overcome a difficulty which could not have been overcome by any change whatever in the cleaning bath.


NICKEL ANODES

By George B. Hogaboom Research Electroplater—The Hansen & Van Winkle Company

A few years ago at one of the conventions, attention was called to the probable effect of the crystal structure of the base metal upon the structure of the deposit. Blum and Rawdon, Bureau of Standards, and A. K. Graham, University of Pennsylvania, investigated this and confirmed the writer’s experience. The study did not include all metals, but there is evidence that it may be universally true. Definite results have been obtained from several solutions.

About the time this was noticed there was also seen evidence that the crystal structure of the anodes materially affected the rate of corrosion and also the character of corrosion. By rate of corrosion is meant the amount of metal dissolved at the anode and which actually goes into solution; in other words; the ability of the anode to keep the metal concentration of the solution nearly constant. The character of corrosion may be defined as whether the metal goes into solution or whether fine particles are released and fall to the bottom of the tank. In some cases this finely divided metal is mechanically carried over and deposited on the cathode and is the cause of rough deposits.

A brass anode that had been cast in a chill mold and permitted to cool in the mold was the cause of this investigation. After this anode had been in solution several weeks it was taken out and examined. It was found that the whole center had been dissolved, while the edges of the anode had decreased very little in thickness. It looked quite like a picture frame with an oval center. An anode made in the same was examined under the microscope and what has long been known was seen. The outer edge, which cooled more rapidly than the center, had a very fine crystal structure. This part corroded evenly and smoothly. The center, which cooled more slowly, had very large crystals and there was evidence of a difference of alloy in the crystal boundaries. The center corroded unevenly and rapidly. There were evidences that the intercrystalline structure was attacked by the solution more rapidly than the crystals themselves. This resulted in crystals, both singly and in groups, being released before they were wholly dissolved. These small undissolved crystals, or metallics, fell to the bottom of the tank and a considerable accumulation could be seen directly under the anode. The deposit in front of these anodes was often rough, and upon examination it was found that the roughness was due to the small particles of metal that had been mechanically carried over to the cathode. By screening the cathode with muslin, this was stopped. From this it was learned that the crystal structure of the anode affected the character of corrosion and that very fine crystals resisted corrosion, while large crystals were often released before they went entirely into solution. It was believed that the ideal condition would be to have all the crystals of the anode the same size, and then in all probability the corrosion would be uniform.

It was known that annealing at different temperatures and soaking for different periods of time gave metals a different crystalline structure. This was especially known in the heat treatment of steel. The physical properties and the behavior in use of alloys of steel depends entirely upon the heat treatment received Each alloy requires a special procedure in heat treating.

With copper or nickel alloys, it was known that to obtain any required structure the metal had to be worked. If it was then annealed and held at a specified temperature for a definite time, a regrowth of the crystals would take place and a uniform crystal structure could be had throughout the whole article. It was also known that cast metal would not be affected in the same way as rolled metal and that while heat-treating might change some parts of the structure it was not possible to obtain a uniform condition throughout. To ascertain just what effect heat treatment had upon cast metal and in turn what effect the resultant structure would have upon corrosion, some cast nickel was annealed. The reason why nickel was selected was because it was recognized at that time that high purity nickel anodes could not be used. Rolled nickel anodes were known to remain in solution almost indefinitely without being attacked.

Cast nickel anodes had a purity of 90-92% nickel and it is only in recent years that 95-97% anodes have been used. The reason generally understood was, that carbon and iron and sometimes tin had to be added to nickel, as up to this time no furnace had been developed for commercial use that would stand up very long under the high temperature required. Another reason is that the high purity nickel then made was almost insoluble in the nickel solutions commonly used. The impurities assisted the corrosion.

The annealed cast nickel anodes did not corrode much better than those not heat-treated. It was noted, however, that many of the so-called “blow-holes” in nickel anodes were not at all “blowholes.” The holes were found in areas where there were large crystals and segregated impurities, especially when the latter existed between the boundaries of the crystals so that they formed an impure inter-crystalline structure. The same phenomenon as had been seen in the cast brass anode was evident. While some parts of the cast nickel anodes showed a slight change of crystal structure after heat treating, this effect was not uniform throughout and there were still the areas of large and small crystals.

The annealing of worked or rolled nickel gave a uniform crystalline structure. There were no evidences of segregated areas or large amounts of impurities in the inter-crystalline boundaries. They had been distributed throughout the whole anode and any amount in a given area was so small that it had little or no effect upon the corrosion of the anode in a nickel solution. An investigation made on a commercial scale, extending over a year confirmed the opinion that the crystal structure of a rolled nickel anode controlled the rate of corrosion and also the character of corrosion. The annealing temperatures and the period of soaking was varied so that different crystal size was obtained. Temperatures ranging from 850° F. to 1800° F. were tried and the soaking was in half hour periods from one-half hour to two hours. It was found that it made little or no difference if the nickel was rolled hot or cold and then annealed, or whether it was annealed above the desired temperature and then hot rolled or worked in any other manner, being careful that the temperature at the completion of the working was at or slightly above the desired annealing temperature. That this was something that had not been recognized before was clearly indicated by the granting of patents in almost every country where patents were granted without any citation of interference or priority.

There are many advantages of a high purity nickel anode over those of lower nickel content. There is no accumulation of sludge in the bottom of the tank. The anodes do not become covered with slimes which act as an insulation and which when so coated require a higher voltage to obtain a required current density. The solution itself is clean and clear. There are no floating metallics or slimes to settle upon the work to cause rough or porous deposits. The character of the deposit is improved and the working conditions greatly improved.

The rolled nickel anode corrodes more evenly that the cast anode. This is due to the absence of impurities in the crystal boundaries and the uniform distribution of current male possible by uniform structure. Nickel is one of the metals most easily affected by gases and impurities. It becomes readily diseased, which results in poor conductivity and uneven corrosion. Ideal conditions must be had at the furnace and these cannot be had where there is small production. There are always gaseous inclusions and inter-crystalline impurities in cast nickel that cause harmful and wasteful conditions in anodes. Often if the hand is run over a cast nickel anode a considerable amount of metallics can be wiped off. These conditions can only be overcome with our present day knowledge by the forging and the several annealings of the cast ingot until it is in a condition to permit rolling. The result is a homogenous piece of metal, uniform in structure throughout, having correct physical properties which contribute to making an ideal anode that will corrode uniformly in a nickel solution.

Manufacturing of Etched Metal Goods

To my fellow members of the A. E. S. and friends assembled here tonight to partake of the three F’s, viz.: Feast, Fun and Folsteadism (phonetic spelling).

My subject is the art and manufacturing of etched metal goods, e.g.: name plates, clock dials and all metal novelties. This industry is by far out of the ordinary compared to industries that manufacture drapery hardware, typewriter parts, silverware and a dozen or more different fields, namely because there are so many details and different artisans required to make an organization complete. For instance, artists to draw the designs, compositors to set up and prove ordinary cast type, wet and dry plate photographers to make the negatives and positives for the zinc plate maker who prepares the zinc necessary for using in any one of the different lithographic offset presses. Then there are all the etchers, platers, lacquerers, metal polishers and last, but not least, the die makers and a hundred and one other menial operations to be taken care of by men that are not required to have any training in any particular line.

To begin with, an order is received for one hundred thousand brass name plates, 3 x 1, (specified) brass, raised letters, dull background, 22 gauge, half hard brass. The customer may want some special kind of lettering which the type casters do not make, so that is operation No. 1 for the letter and design artist to draw any special type letters or designs that are required on the plate. Whatever plain type is required, such as the address, it is set up by the compositor and printed on small slips of a good, white stock of paper, which is pasted on, or in other words, inserted in the drawing that the artist has finished his special lettering, and designed on.

NO. 2
The drawing is now ready for photographing. Every company has a different method of handling their work. As a rule, there are different scales of drawing, e.g.: 1-1, 2-1, etc., up to 8-1. By this scale is meant, if a finished name plate should measure 3 inches long by 1 inch wide, the lettering thereon would be too small for the artist to make, so the drawing is made 9 inches long by 3 inches wide, so when the photographer makes the negative he reduces it to 3 by 1, which rates that particular drawing 3-1. It also has a tendency to sharpen the lines on a drawing. For instance, a letter may be a trifle ragged on a 3-1 drawing. When it is reduced it loses 2/3 of this raggedness. Four or five of these drawings of different designs are placed on the copy holder of the camera and a wet plate negative, 10 x 12, is made. This negative is then intensified and coated with gum or gelatin to protect it from being scratched. It is then retouched and placed in the camera again, but this time it is photographed as a positive, which means a black letter on clear glass. This positive is made on a 5 x 7 glass. It is treated as the first negative, then placed in the step and repeat camera, which makes the final negative to be used for producing the zinc plate for the lithographic presses. These negatives are made according to the size of the sheet of metal being used to print on. The final step and repeat negative is then placed in a printing frame having a sheet of grained zinc, such that is used in the lithographic presses. This zinc is coated with a solution composed of ammonium, bichromate, albumin and water.

It is whirled until dry, then it is ready to be placed in contact with the negative. The printing frame is locked and exposed to sunlight or ordinary carbon arc lamps until the action of the light ha hardened the exposed parts in the negative. The zinc is then taken out, placed on a slab and rolled up with a leather covered roller. It is then placed under the tap, those parts that have been exposed remain on the zinc, the rest of the solution and ink will wash away. This zinc is then etched as all plates for lithographic printing are. It is then ready for the press. The metal is received in sheets 8 3/4", 9", 9 1/2" and 11" in width, and in multiples of 10" or 11" in length, total lengths of sheets being 70 to 78 inches. As a rule 3 x 1 name plate negatives, are made with 30 exposures on the step and repeat camera, 10 in a row, which measure 10" and 3 rows which measure 9", which makes the actual square inch surface 90 sq. inches. The metal being used is 9 1/2" wide and 11" long, so it leaves a margin of 1/4" on each side and 1/2" on each end, which enables the pressman to handle and examine the plate after the impression has been printed thereon. But, of course, we have to have metal to print on so we will go on to operation No. 3.

NO. 3
The polishing and buffing of all sheet brass, bronze, copper, nickel, silver and steel is done on a Weisbecker polishing machine, which no doubt, some of you gentlemen are acquainted with. But for the benefit of those who are not, I will briefly outline the construction of the same. It is composed of a large cast iron drum, about 36" in diameter, the face of the drum ranging from 24" to 36" in width. This face is covered with 2" thick cypress or any suitable wood, upon which is fastened a good quality of hard felt, 1" to 1 1/4" thick. This is the polishing member of the machine. This drum revolves at an approximate speed of 120 revolutions per minute. The feed roller is a steel roller about 4" in diameter which travels at a speed of 20 revolutions per minute. The right pressure is brought to bear between the feed roller, which his directly underneath the felt drum. The sheet of brass is placed on a rest directly in front of and in line with the center point between the feed roller and drum. The polishing medium is a 00 pumice, and a good heavy machine oil. This polishing medium is held in a deep sheet iron container which is bolted onto the frame of the machine. The operator sprinkles a few handfuls of the polishing medium evenly on the sheet ready to insert between the rollers. If the proper distance or pressure between the roller and drum is not correct, the sheet will shoot through before the operator has a chance to wink an eye, and also runs a chance of cutting his fingers to the lone, or even be minus a few of his digits. But if the proper distance or pressure for each gauge is maintained correctly, the sheet will travel through at a moderate rate of speed. It is generally run through two times, which produces a nice grain finish for the automatic buffing machine to finish. If a buff finish is not required, the metal is taken directly from the Weisbecker machine and cut into the lengths required, which usually is 11 or 12 inches. These sheets are then run through a special benzine washing machine to remove all the oil and pumice. They are then slotted, if the customer’s order specifies a copper, nickel, or silver raised letter on dull background, the slot being used to insert hook for plating. If the order calls for brass, raised letters, the sheets are not slotted. They are taken directly from the benzine machine and rubbed with Vienna lime, which removes any possible trace of grease. The sheets are then heated slightly so the lithographic or etching ink has more adhesive power. The plates are printed on an offset hand fed press. They are then powdered with an etching powder. The surplus powder is then brushed off the brass, only remaining on the ink impression. It is then baked at a temperature of 300° F. for about 10 minutes, which can be done in a mechanical conveyor, which contains the necessary heat and speed to burn the powder to obtain the proper resist for etching. When cool, the back of the sheet is coated with a thin asphaltum varnish to prevent the etching of both sides of the metal. If the finish should be as stated before, in copper or any other metal deposit, the sheets are plated and then printed and handled the same as brass.

Etching and oxidizing of (sheet brass) copper, nickel and silver plated brass are placed in hard rubber containers which are rectangular cast hard rubber boxes, without a bottom. Just a flange all around the bottom to stop the sheets from falling through, and slots on the four inner sides to slide two plates in each slot vertically, back to back. There are generally 15 slots, which make a total of 30 sheets per box. These boxes have two handles cast on the top at each end, to allow strong hooks to hang them in the etching tanks. These tanks are ceramic, about 6 feet long, 30” deep and 24” wide. These tanks are equipped with hard rubber perforated pipe to allow a large amount of compressed air to enter the bath from all angles to produce an agitated solution which etches uniformly. This cannot be accomplished if the solution is not agitated. The etching would be streaky and uneven. The etching solution is technical or commercial (Fe Cl3) Perchloride of Iron. The sheets remain in the bath from 10 to 20 minutes, depending on the depth required. The sheet brass and copper plated sheets will etch quicker than nickel and silver plated brass, for it requires a longer time to etch through these two metals, which must be done to obtain a brass ground for the copper carbonate Ammonia Black Oxidizing solution to function. After the proper etch, the sheets are run through a Sodium Bichromate and Sulphuric Acid bath to remove scum that may remain from the Iron Etch. This gives the metal a clean and bright finish. They are then run through a weak Sulphuric Acid dip, which has a tendency to aid in oxidizing. After oxidizing, the sheets are rinsed and allowed to air dry in racks such as are used to hold negatives. After drying they are soaked in benzine and run through the sane automatic benzine cleaning machine to remove the resist and asphalt backing. They are then lacquered and are ready to be sheared, formed and blanked on the power presses.

NO. 5 (CLOCK DIALS)
If a customer requires black raised numerals and graduations on silver ground, the brass is not silver plated to start with. The brass sheet goes through the regular course of polishing, printing, powdering and burning, but instead of the iron etch, the sheets are etched in a solution of Sodium Bichromate and Sulphuric Acid which etches the brass with a fine grain. The sheets are swabbed with a soft sponge and flashed in the acid copper bath, rinsed, and then silver plated, which produces a fine white grained silver ground. After being scoured with Bicarbonate of Soda, the sheets are air dried and placed in the automatic benzine cleaning machine, to remove the resist and asphalt backing. The sheets are then scoured with Vienna Lime, and placed in the Ammonia Ox. Solution, which does not affect the silver plate, but oxidizes the numerals and graduations, which gives us the finish of black raised letters and silver ground. The plate when dry, is lacquered and blanked out. If a black depressed letter is wanted on a silver ground, the sheet is handled the same as above, until it reaches the etching stage. These sheets are etched in the Iron Solution, as the etching must be considerably deeper, to allow the filling-in of numerals and graduations with black enamel. The enamel is scraped over the sheet and the surplus taken off with a brass scraper, then baked for about five hours at the ordinary temperature of baking enamels. The sheet is then scoured with pumice and hard felt to remove all traces of enamel from the surface, the enamel remaining intact in the numerals. The next operation is to produce the fine grain surface which is done in the Sodium Bichromate Sulphuric Acid Bath, which is agitated the same as all etching baths. When the proper grain finish is obtained the sheet is swabbed with a soft sponge and flashed in the Copper Sulphate Bath. Then a few minutes silver plate is deposited, scoured with Sodium Bicarbonate, air dried, lacquered and then punched, blanked and formed.

NO. 6
If a solid copper nameplate is wanted, with copper raised letters and black ground, the sheet is handled the same as for brass raised letters but the difference is in oxidizing. The copper cannot be oxidized in the regular Copper Carbonate Ammonia Oxidizing solution, so we must make use of either Potassium Sulphide or the black nickel I prefer the latter, with all its faults. For in the name plate industry, we look for blacks that are blacker than black. For that reason we do not and cannot depend on the Sulphurette as it produces a dark gray oxidation.

NO. 7
Sheet Aluminum is not run through the Weisbecker polishing machine. It is just given an automatic buffing and then cut to the proper size sheets for the press to print. It is handled the same as all the metals that are printed until it reaches the etching stage. This metal acts very peculiar, as we all know, those who have tried to plate Aluminum on a commercial basis have no doubt rejoiced when they deposited a certain amount of copper from the cyanide solution without blistering, and- really thought they had discovered one of the lost arts, to find out in about six months or less that the bubble of their dreams had ascended too high to stand the atmospheric pressure and Bang ! ! ! Presto ! Chango ! Where can my copper be ? Some have advocated dipping the sheet in a solution containing a certain percentage of Perchloride of Iron, before plating, it may help some, I’ll agree; others give a formula for a black oxidizing solution composed of Muriatic Acid, Sulphate of Iron, Arsenic and Water. This may give a gray deposit of Arsenic, then to make matters worse (it continues— add a small portion of Sulphate of Copper), that is when the fun begins. If any of you gentlemen wish to try the oxidation of this freak metal, just make up a solution composed of HCL, 1 gallon Muriatic Acid; As203, 2 ounces White Arsenic; Fe S04, 1 ounce Sulphate of Iron; H2O, 1/4 to gallon water. Now scour the sheet of aluminum to remove the bright luster as you receive it from the mill. Immerse in the above solution and you will receive a gray deposit. Start to add a few drops of concentrated sulphate of copper solution. It will improve the color 1/10 of 1/100%, then add a few drops more and see what will happen. You will get a lovely black deposit, but you can rub it off and dry it to use with turpentine for stenciling cases for shipment. When the aluminum sheet is ready to be etched, it is placed in an etching bath composed of perchloride of iron, muriatic acid and water. There is a violent action of hydrogen gas, enough to fill the containers of a dirigible, and also to frighten a man doing his first etching on aluminum. After 3 or 4 minutes the sheets are taken out and rinsed and placed back again. If this were not done, the heat generated during etching would soften the resist and etch through, destroying the plate. By removing the sheets it also allows the solution to subside and find its level. After the proper depth has been reached the sheets are given a quick dip in a commercial muriatic acid bath. They are then placed in the regular black nickel bath somewhat higher in metal, in fact all the amounts of the other ingredients are increased. I have also found it an advantage to find one or two cakes of Kirkman’s soap at the bottom of the tanks, which some of the so-called platers from the Far East would accidentally, on purpose, drop into the tank to try and cause trouble for the man in charge. If he did not comply with their request for “Mr. Boss, please give me a raise.” So you see, it does not matter so much if we add one or two cakes of soap to every 100 gallons of black nickel solution to neutralize the acidity of the bath.

NO. 8
There is another finish of clock dials that are termed “Circular Finish.” These sheets are handled the same as the dials with depressed numerals and graduations, but instead of finishing the whole sheet, which may have four or more etched in it, could not be finished in the sheet form. The etched sheet, after it is enameled, filled and scoured to remove all surplus enamel, is blanked, perforated and formed. It is then placed on a horizontal disc, revolving at the rate of about 1700 R. P. M. It is ground off with 00 emery cloth, having a drip cock feeding water on the dial. After the proper finish is obtained it is transferred to another disc, revolving at about 600 R. P. M. The silver is deposited by friction which has a light gray cast. To remove this, the dial, while in motion, is scoured with cream of tartar. These dials are dried in sawdust to prevent oxidation, lacquered, inspected and shipped.

Hoping I have expressed in a simple and comprehensive manner each and every operation necessary to produce etched metal goods.

Sincerely yours, FRANK LOEB

 

 



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