US1930826A - Process for reproducing the surface of plates - Google Patents

Description

0t.17,1933. 1 H, B, SCOTT T L 1,930,826

PROCESS FOR REPRODUCING THE SURFACE OF PLATES Filed 001:. 5, 1928 F|G.2 M ig 9 8 g {/5 gwumflom/ Howard B. Scott and Charles C. Conley X is so related realistic.

EPatented Oct. 17, 1933 PROCESS FOR REPRODUCING THE SURFACE OF PLATES Howard B. Scott and Charles Ohio, assignor to The Ohio Company, Dayton,

C. Conley, Dayton, National Cash Register Application October 5, 1928. Serial No. 310,610

4 Claims.

The object of this invention is to provide an improved process whereby the graining of woods may be reproduced on substances of other nature than wood, such as sheet steel or the like in the manufacture of metal furniture for home and ofice use, cabinets for machines, panels for Walls of stationary or movable structures, or the walls themselves.

This invention is devised as an improvement upon the Well known Henry process disclosed in United States Patent No. 1,548,465,-iss ued August 4, 1925, and in order to fully disclose the improvements thereon, disclosed hereinafter, it will be necessary to describe the Henry process, which to the present improvement as to combined therewith in the formation of a novel process for producing the surfaces from which the representation of the particular graining effeet, is transferred to the article or surface to be thus decorated.

One object of this invention is the reduction in expense incident to carrying outthe Henry process.

This reduction is obtained in two ways. First, in the Henry process, the copper plate after being etched, was itself used as the graining plate on which the pigment was first spread, the surplus pigment removed by a scraper or doctor blade, and the remaining pigment picked up by the transfer roll'to be applied to the surface to be ornamented.

Obviously, the etched surface of the copper plates wore down in use, and the pattern etched therein became of forming such copper and expensive, a certain per'mittedbefore the plates dition, produces a graining plate, the pattern on which will outlast the etched pattern on the copper plates produced under the Henry process, thus afiording the graining plate a longer life 1n use.

reproduction other subject, ing thereof.

To better appreciate this, it will be remembered of the same identical graining or together with the tones and shad- 'fainter and less distinct and that, under the Henry process, the actual board,

treated to bring out the characteristics of pore and shadings, was

photographed, and through several steps a reproduction of this photograph was etched on the copper graining plate. But such etching varied with each operator,

some of whom obtained clearer and more distinct outlines than others.

Obviously, a single graining plate would not be sufficient when transf erring the reproduction to a large area, as the walls of a room, or a large number of panels, as

in a Pullman car, or even a large number of articles.

Also, the use of but a single graining plate from which to transfer the rially limit the number work on the job.

Hence it was customary to reproduction, would mate-- of operators who .could provide a plurality of graining plates, but even when they were prepared from the s ame original photograph,

their treatment during the etching period resulted in differences in depths of pores, shadings and other minute characteristics, which differences were brought out by the pigment the surface to be ornamented, so that one could distinguish the reproductions from the By the improved number of graining several plates.

process or method, a large plates can be produced,

which are absolutely similar reproductions identical in every detail, force of workmen to vidual of which to the surface thereby enabling a large be employed, each indimay transfer the reproductions to be ornamented from absolutely faithful and exact duplicates of the original plate, so that even may be preserved.

quality and verisimilitude And in order to more clearly explain this method, a sheet of drawing is filed herewith as a part of this application,

to diagrammaticallyillustrate the novelfeatures of the invention.

In the drawing: I

Fig. 1 is a diagrammatic representation of the formation of a mother plate, and

Fig. 2 is a similar representation of the formation of a "graining plate.

'plate from the mother" In the Henry process, when reproducing the grains of quartered oak,

mahogany, or any other woods having grain, which it is desired to imi tate, a piece of wood selected so that the natural and artistic as of selected grain, the s as nearly smooth as of desired grain is first reproduction will be as possible. Havingaboard urface of the same is made possible by the ordinary planing and sanding operations, and is then given a stain. The pores of the wood will accept the greatest amount of the stain, and thus become the darkest places in the planed surface. The tone is gradually blended off to the high lights or hard spots in the surface of the wood.

The surface of the board, thus prepared, is then photographed, reproducing the grain on the negative by the usual photographic process. From the negative so obtained, a positive is made, preferably on a photographic film or clear glass, which positive is also obtained by the ordinary photographic process.

Having obtained the positive, a print is made therefrom on a sensitized photogravure carbon' tissue paper, such as ordinarily employed in the intaglio process of printing.

It has been found desirable to separate the etched areas to be later obtained, and the use of screens as practiced in photogravure is resorted to. Thus, after exposure in making the print on the carbon tissue, the latter is again exposed to light through a screen, preferably of transparent thin lines ruled on glass and crossing each other so as to leave opaque squares, instead of transparent squares as in an ordinary half tone screen. This form of screen is well known as the Rembrandt screen in the art of rotary photogravure. Any form of screen may be used, such as straight line screens, wave line screens, etc., without departing from the spirit of the present process.

The purpose of using the screen, as above described, is to break up the etched area into small recesses or cells, which vary in depth according to the shaft to be reproduced, and are adapted to receive masses or fields of pigment, as hereinafter described. This breaking up of the etched areas eliminates entirely the difiiculties formerly encountered in the use of a wiper or doctor blade. When a wiper or doctor blade is used on a hand engraved or etched metal plate bearing a reproduction of a long open-grained piece of wood on which the etched or engraved area is not broken up, the doctor or wiper blade tends to draw out of the unbroken depressions more than mere surface pigment, especially when the wiper blade is drawn over the plate in the direction of the grain. This results in leaving in said unbroken depressions an insufilcientamount of pigment to give a faithful reproduction. With the present invention, however, the small cells into which the etched areas are bfiken up prevent the excessive withdrawal of the pigment by the wiper blade which can then only remove the surface pigment, the small cells retaining the proper amount of pigment which is calculated to give a faithful reproduction of the shades and grain to be reproduced.

The carbon tissue, so prepared, is first allowed to soak in a solution of alcohol and water of equal parts to soften the tissue which is then placed face down in contact with the burnished metal plate to be etched and is squeegeed into complete contact with the plate.

When the tissue is exposed through the positive and the screen, certain portions of the sensitized gelatin are hardened to form an insoluble resist for the etching operation. After the tissue has been thoroughly squeegeed in contact with the copper plate, warm water is employed to' loosen the paper backing, and to wash away that part of the sensitized gelatin which is soluble, leaving a deposit of insoluble gelatin or resist on the face of the plate. Thus the image of the graining of the wood is produced on the metal plate in gelatin photogravure relief corresponding to the lights and shades of the positive through which the light acted. Where the positive is densest, the resist is thinnest and where the positive is transparent, the resist is thickest. When this process of development is completed, the plate, with the resist, is allowed to dry thoroughly.

The edges and other surfaces of the plate which have not received a deposit of resist, as above stated, are now protected with a coating of asphaltum preparatory to etching in the usual manner, preferably with ferric chloride, as a mordant. It is found desirable to employ three baths of average variation in strengths running from 45 degrees to 40 degrees Baum, the variation in climatic conditions determining the strengths to beused, practice showing that in warm weather it is often preferable to start at 48 degrees Baum, while in colder weather it may be desirable to drop to 36 degrees Baum. Any weak points in the etching may be further developed by local etching by any of the well known methods.

After the plate has been satisfactorily etched, the action of the mordant is stopped by the application of a potash bath which also serves to soften the gelatin resist so that it can be brushed from the plate.

It will readily be understood that in the carbon process when the plate is put through the etching baths, the mordant penetrates the thinnest parts of the gelatin resist first, and therefore. etches the plate deepest under these parts. Where the resist is thickest, corresponding to the high lights of the positive, the mordant has the least effect on the plate and the etching is the slightest or shallowest. As a result, where the high lights appeared on the positive, the cells formed in the copper plate will be comparatively shallow,

-while in those parts where the positive was darkest, the cells formed will be correspondingly deep. As the etching is controlled from a true photographic negative of the grain to be repro duced, the varying depth of the cells so formed are such as will give a faithful reproduction of the exact pattern of the grain, together with the proper shades.

The foregoing constitutes that portion of the Henry process, leading up to and including the preparation of the metallic etched plate 5.

- The present improvement to the Henry process occurs at this stage in such process.

The actual photo-engraved copper plate 5 (Fig. 1) produced in accordance with the foregoing process, was used by Henry in the further steps of his invention of transferring reproductions of natural patterns onto surfaces to be ornamented.

But, as explained in'the preamble, such plates are expensive and of comparatively short life.

Therefore, the present improved process con- 5 templates'the method of maintaining the exact photographic reproduction, from which to transfer pigment to the surface to be ornamented, without utilizing the original copper plate 5 for the application of pigment.

To this end, the original copper plate 5 bear- .ing the etched reproduction is preserved as a or mother and in turn,

master plate, reverse master plates plates being produced therefrom,

ant before the nickel film '7 .10, 11, Fig. 2)

the actual graining plates produced from the mother plates.

One method by which this process may be carried out, is to mount the original photo-etched copper plate 5 on a suitable rigid metal frame 6, the inner edges of which are preferably reduced to form a seat for the outer edges of the plate 5, (see Fig, i), so that the etched surface of the latter lies in substantially the same plane with the unreduced body or face of the frame, and secure the original copper plate to the frame in any convenient manner, as by soldering, after which the reverse sides of the original copper plate and of the frame are coated with wax, asphaltum or a similar plating resistant, and the original plate and frame immersed in a nickel elect'ro-plating bath, which applies a nickel facing or film 7 (Fig. 1) about .0001 of an inch thick to the bare etched face of the original plate 5. The wax, asphaltum or similar coating prevents the adherence of the nickel to the reverse side of the original plate, which now becomes the true master plate, and will be so referred to hereinafter.

The nickel film or facing 7, thus applied to the etched face of the copper master plate 5, is for the purpose of providing a suitable stripping surface on which laminae forming a mother plate or reverse master plate may be deposited and from which surface such mother plate may be readily stripped or removed without injury to the master plate.

The nickel-plated master plate 5 is now immersed in an electrolytic caustic cold bath, such as a 10% to solution of caustic soda (sodium hydroxide) at a current density of to amperes per square foot of surface of the master plate, in which bath the master plate remains for about two-seconds, connected to and forming the anode of such bath.

This anodic treatment of the nickeled face of the master plate 5 in a caustic solution apparently causes a film of nickel oxide to be formed on the face of the master, but whatever the exact action may be, the nickeled face thereon so treated, permits the mother plate formed of acorticular nickel layer backed up by alternate layers of copper and nickel, subsequently applied to the nickeled obverse side of the master plate, as hereinafter explained, to be readily stripped therefrom.

Assuming that the reverse side of the original copper plate 5 was coated with a plating resistwas applied directly upon the etched copper face thereof, the subsequent treatment anodically in the'caustic bath has no effect on the plating resistant because of the short length of time the plate remains in the bath coupled with the fact that the cold caustic solution will not attack the plating resistant.

After the anodic treatment, the master plate 5 is removed from the caustic bath and thoroughly rinsed, preferably in warm water, to remove the caustic solution, after which the reverse sides of the master plate and frame, if not already so treated, are coated with wax, asphaltum or other suitable plating resistant, and then immersed in a special nickel electro-plating bath, which applies to the nickeled face of the masterplate a corticular shell 8 of nickel about .005 of an inch thick.

The shell 8 constitutes the-face of what will be the mother or reverse master plate (8, 9, when completed, and this shell sition of the metal together withthe laminations applied thereto, as hereinafter explained, must be stripped or separated from the nickeled face 7 of the master plate 5, for use in preparation of the graining plates. I

It has been found that the customary nickelplating bath deposits a shell 8 of a brittle nature which cracks, and curls away from the nickeled face 7 of the master plate, and seems to fail to closely hug such face, during and after the depothereon.

To cure this disadvantage, a special nickelplating bath is provided, which deposits a tough nickel shell which will not crack, even when bent, and which conforms closely to the face of the master plate.

While many formulas might be used in making up such special bath, and kindred chemicals substituted for those hereinafter set forth, as well as variations in the proportions, good results have been obtained by the use of a bath comprising:

' Ounces Single nickel sulphate (NiSO47II20) 16 Nickel chloride (NiClz) 2 Sodium sulphate (Nazsoi) l Boric acid (HsBOs) 1 to a gallon of water.

And since it is desirable to maintain the bath at a normal degree of acidity, the hydrogen ion concentration should be lowered and held at 5.7-5.8 degrees by the addition of acetic acid (HC2H3O2) to the above mentioned bath, which element must be frequently introduced inorder to maintain the above mentioned hydrogen ion concentration.

Preferably the temperature of the special bath is held at about 110 to 125 degrees F. more or less, and the solution must be clean, to maintain which condition it may be continuously filtered, though this continuous filtering is not imperative if other means of securing a clean solution is employed.

Anodes of 99.9% nickel should be used, and in the process of depositing the metal on the nickeled face of the master plate to form the shell 8, it has been found highly desirable to maintain the solution agitated, either by sousing the master plate up and down in the bath, or by the discharge of compressed air into the bath, during the plating period.

Magnesium sulphate may be substituted for the sodium sulphate, if desired.

The ordinary nickel-plating bath contains no acetic acid, and has a far higher proportion of This special bath can be used, if desired, to

apply the thin film nickel stripping face '7 to the copper face of the master plate 5.

The master plate 5 with the nickel shell 8 on its face is then transferred to a copper electrolytic bath and a backing of copper 9 from .010 to .015 of an inch thick is plated onto the exposed face of the nickel shell.

Successive alternate layers 10 of nickel and copper or other suitable metals are similarly deposited on the exposed face of the copper layer 9 last mentioned until, preferably, there are six layers (nickel and copper) including the nickel shell 8 applied to the original nickeled stripping face 7 formed on the original etched copper master plate 5.

In this manner, a mother plate is formed, comprising the nickel shell 8 backed up with a entire nickeled stripping face 7 of the master plate 5 and its frame 6.

The edges of the mother plate thus formed,

are now loosened from the master plate and its frame, and the mother plate readily stripped or peeled from the caustic-treated nickeled stripping face '7 of the master plate 5.

The nickeled face 8 of this mother plate bears, of course, the photo-etched reproduction of the face of the master plate 5, in relief.

The nickel stripping face 7 of the original etched copper plate or master plate 5 is hardly more than a very thin film which does not appreciably fill up the representation of the graining etched in the master plate.

From the mother plate thus formed, numerous graining plates are produced, preferably by a similar method of building up.

To this end, the mother plate is first mounted on a frame 11 similar to that in which the original etched master plate 5 was mounted. The frames strengthen and protect the master plate and mother plate and enable them to be more easily handled and stored without defacing, bending or otherwise damaging them.

The frame for the mother plate need not be quite as elaborate as that for the master plate, as the mother plates in time lose the distinct outline of the graining, or sharpness of detail, due to the repeated stripping of the graining plates therefrom, and new ones must be obtained from the master plate in the above-explained manner.

Having mounted the mother plate in a frame 11, the plain or reverse sides of the mother plate and frame may be coated with a suitable plating resistant, as in the case of the master plate, after which, the mother plate is anodically treated in the caustic solution as in the case of the master plate, to enable the graining plate hereinafter formed, to be readily stripped from the nickeled face 8 of the mother plate, bearing the desired representation in relief.

Thereafter, the mother plate thus treated,

is rinsed to remove the caustic solution, and is then soused in the special nickel electro-plating bath heretofore set forth, until a face 12 of nickel approximately .005 of an inch thick is formed on the face of the mother plate bearing the desired representation in relief.

The mother plate with the nickel facing 12 clinging thereto, is then hung in a copper electroplating bath, and a layer of copper 13 about .010 to .015 of an inch thick deposited on the exposed side of the nickel face, alternate layers 14 of nickel and copper being similarly applied to the copper layer last mentioned, until the desired 2 thickness, strength and rigidity is obtained,

whereupon the mother plate with the superimposed layers of nickel and copper adhering to its face, is transferred to a lead plating bath, and a layer 15 of lead of substantially .004-.005 thickness, more or less, deposited on the exposed side of the outermost layer 14 of copper.

This deposit of lead gives weight to the plate to cause it to lie flat on the graining table.

Furthermore, the lead affords a backing metal which is easily worked and smoothed down to a plane surface, thus eliminating any roughness due to prolonged plating.

After smoothing the back of the graining plate in any suitable or convenient manner while it is still attached to the mother plate, the graining plate is loosened around its edges from the mother plate and stripped or peeled off.

The nickel face 12 of the graining plate thus exposed, which is the nickel sheet applied directly to the anodically treated nickel relief face 8 of the mother plate, bears the desired reproduction of graining, for example, in intaglio, and after being trimmed to the proper size, is ready for the final operation of reproducing the graining photo-etched upon the master plate 5.

If it were commercially practicable, it would be preferable to form this graining plate of a solid deposit of nickel, instead of alternate layers of nickel and copper, but the formation of such a solid nickel plate electrolytically would require a comparatively long time, and would be so rough as to be impractical, as well as expensive.

The hard wear-resisting nickel facing 12 of the graining plate is obtained by forming the shell of a specially deposited tough nickel, the face of the shell bearing the duplicate of the etched face of the master plate, and the necessary rigidity and body is obtained by the alternate layers of copper and nickel constituting the backing for such nickel shell, the layers of copper being thicker than the layers of nickel, and more quickly applied, as well as being a less expensive metal, thus materially decreasing the length of time required to make a graining plate compared with the length of time necessary to form a graining plate according to the Henry process, as well as decreasing the expense of labor and material.

Furthermore, graining plates made in accordance with this method with nickel graining faces 12 remain in condition for use longer than do the originally etched copper plates 5 of the Henry process, and this invention enables exact duplicates of the master plate to be obtained so that there will be no variation in the appearance of the surface being ornamented, when one graining plate is substituted for another.

And in addition, the process enables several graining plates identical in every respect to be made from the mother plate, so that several operators may work at the same time, applying 120 exactly similar representations of graining to a number of surfaces, as metal cabinets, or on different areas of the same surface, as the walls of a room, panelling, or the like.

The mother plate may be anodically treated 125 time and again and returned to the plating baths to repeat the foregoing process of producing graining plates.

Likewise, a number of mother plates can be reproduced from the master plate by following the process above outlined in connection with making the first mother plate.

That face of the graining plate 12 bearing the duplicate of the etched face of the master plate 5 may be given a very light chromium deposit to increase the life of the plate and afford a better wear-resisting surface.

It should be borne in mind that the characteristics of a master plate formed by the photoetching process using a screen, differ materially in some respects, from a master plate formed by engraving, either by direct incision or by acid, and such differences in characteristics dictate the process adapted to give the best results in reproducing such master plates. 145

In the usual engraved master plates obtained by directly incising the metal, or by covering the plain-surfaced master plate with a protective coating and engraving the design through the coating, which is then etched into the plate c from master with acid, the walls of the design so formed, particularly when Also, such V-shaped walls more readily lend themselves to the production of mother plates plates by pressing the ductile and relatively soft metal of the mother plate against the intaglio face of the master plate, the cameo design on the mother plate being readily disengaged or released from tthe intaglio design in the master plate.

With master plates formed by the photo-etching process, in which a screen has been used to break up the shades into a quantity of infinitesimal pores of varying depths, invisible to the naked eye, a different condition is faced.

The etched areas are found to be somewhat undercut in cross-section, so that in case of soft metal mother plate is pressed against the master plate, it cannot be released without distorting the fine microscopic design or pattern.

Furthermore, owing to the resistance of the flow into the undercut pores and completely reproduce in cameo, the intaglio design of the master.

Also, the pressure exerted upon the mother will buckle or-bend the mother plate, which is fatal to the reproduction of a completely identical printing plate therefrom.

Another point of difference to be borne in mind between the reproduced plates of the prior art, and the present invention, lies in the manner of use of the respective plates, and this, too, exercises a bearing on the process of forming the plates.

In the prior art, the reproduced printing plates are of relativelS small Should the operator apply the roll with pressure to the work, and flexible, would or design.

It will be noted that an excess amount of pigment is applied to the printing plate, which sinplus is removed by stroking with a doctor blade.

the roll, which is very soft distort and ruin the pattern printing plate is not perfectly fiat, the doctor blade cannot remove the surplus pigment which lies in the unintentionally formed low spots, and consequently, the representation is spoiled.

Forming the mother plate by pressure would surely buckle or bend a plate the size of that used in the present invention, and unless it could be leveled, the resultant printing plate would be out of true, surplus pigment would be left in the low spots, and the design on the high spots would soon become indistinct because of excessive wear.

A very advantageous feature of the present in- 5 vention lies in the provision of laminations of relatively soft and hard metals alternately.

A solid nickel backing on either the mother plate or the printing plate would require considerable time to form and be expensive. It would also be rough or pimply, and be very liable to crack. Furthermore, such'backing would not permit straightening, if required.

By apply alternate layers of relatively hard and soft metals to the backs of the nickel the nickel printing plates, the nickel plate is toughened or cushioned to reduce its tendency to crack, and such layers can be more quickly formed and are less expensive than the nickel.

The operation of reproduction of the actual grain on surfaces to be so ornamented, is as follows:

The graining plate is coated with a pigment of the same color as the darkest lines or pores desired of the grain to be reproduced. After the plate has received the coat of pigment, a wiper or doctor blade is brought against the surface of the plate near one edge and drawn across the surface so that all the surface pigment is wiped. off, leaving a deposit of the pigment in all of the cells formed by the etching process. Having wiped the surfaceof the plate, a soft elastic roller is rolled over the surface of the plate. The roller picks up the pigment in the cells of various depths, which variation in depth of the cells controls the sizes of the masses of pigment, and will govern the variation in color in the reproduction of the grain.

Having thus picked up on the roller the pigment from the cells of the plate, said roller is rolled over the part or article to be grained, said part having been previously painted or enamled with a suitable ground color, such as required for the grain to be reproduced.

When the soft roll, bearing the pigment picked up from the cells of the plate, passes over the article to be grained, the small masses of pigment picked from the cells will be merged. All lines of union between the masses will be obliterated, and all traces of the small etched areas or cells of the etched plate will be destroyed. The varying masses of pigment on the roll due to the varying depths of the cells on the etched plate determines the varying shades to be reproduced and applies to the work an exact facsimile of the original board photographed.

Of course, it is to be understood thatthe color of the pigments and ground colors depends en-' tirely upon, and is varied according to, the wood or finish to be .reproduced. After the pigment has been transferred from the roller to the article which is to bear the reproduction, it is desirable, in order to give a more natural appearance, to

brush over the grained surface with a soft blending brush. This blending operation, however, is not necessary under all conditions and may be dispensed with, without departing from the spirit of the present process.

It is to be understood that it is not intended to confine the invention to the exact method or process herein set forth, as changes can be made of the ingredients used, and of thesteps may be interchanged in the order of procedure, or entirely omitted, without departing from the vention.

What is claimed is:

1. The process of duplicating the surface of an intaglio grained master plate, to form a graining spirit and scope of this inplate, comprising coating the back of the master plate with a plating resistant; electro-plating a thin film of nickel on the face of the master plate; anodically treating the master plate in a caustic solution and rinsing off the plate; electroplating a corticular layer of nickel on the nickeled face of the master plate; electro-plating alternate and successive layers of superposed copper and nickel on the exposed side of the corticular layer to form a backing therefor; stripping the corticular layer with its superposed backing layers as a unit from the master plate to form a mother or reverse master plate; anodically treating the mother plate so obtained in a caustic solution and rinsing; applying a plating resistant to the back of the mother plate; electro-plating a corticular layer of nickel to the face of the mother plate; electro-plating alternate successive layers of superposed copper and nickel to the exposed side of the last-named corticular layer to form a backing therefor; electro-plating a layer of lead on the outermost layer of copper; smoothing the lead-coated back of the plate to make it lie flat; and stripping the graining plate, including the last-named corticular layer of nickel with its superposed backing layers from the nickel face of the mother plate.

2. The process of duplicating the intaglio surface of a grained master plate, comprising electroplating a thin film of metal on the face of the master plate to form a stripping face; anodically treating the master plate in a caustic solution to prepare the stripping face; electro-plating a corticular shell of Wear-resisting metal on the stripping face of the master plate; plating a backing on the exposed side of the corticular shell; removing the mother plate thus formed from the stripping face of the master plate; anodically treating the mother plate in a caustic solution; electro-plating a corticular sheet of metal on the cameo face of the mother plate; plating a backing on the exposed side of the corticular sheet; applying a layer of easily workable metal to the exposed face of the backing; smoothing off the last-named layer; removing the graining plate thus formed from the face of the mother plate; and plating the face of the graining plate with chromium.

3. The process of duplicating the intaglio surface of a master plate, including the steps of electro-plating a thin film of metal on the intaglio face of the master plate; anodically treating the coated face of the master plate; electro-plating a shell of wear-resisting metal on the coated face of the master plate; plating a backing on the exposed back of the shell; anodically treating the cameo face of the mother plate; electro-plating a sheet of metal on the cameo face of the mother plate; plating a reinforcement of a different metal on the exposed back of the sheet; applying a layer of easily-workable metal to the exposed face of the reinforcement; and smoothing the last-named layer.

4. The process of duplicating the surface of an intaglio grained master plate, to form a graining plate, comprising coating the back of the master plate with a plating resistant; electro-plating a thin film of nickel on the face of the master plate; anodically treating the master plate in a caustic solution and rinsing off the plate; electro-plating a corticular layer of nickel on the nickeled face of the master plate; electro-plating alternate and successive layers of superposed copper and nickel on the exposed side of the corticular layer to form t a backing therefor; stripping the corticular layer with its superposed backing layers as a unit from the master plate to form a mother or reverse master plate; anodically treating the mother plate so obtained in a caustic solution and rinsing; applying a plating resistant to the back of the mother plate; electro-plating a corticular layer of nickel to the face of the mother plate; electro-plating alternate successive layers of superposed copper and nickel to the exposed side of the last-named corticular layer to form a backing therefor; electro-plating a layer of easily workable metal on the outermost layer of copper; smoothing the lead-coated back of the plate to make it lie flat; and stripping the graining plate, including the last-named corticular layer of nickel with its superposed backing layers from the nickel face of the mother plate.

HOWARD B. SCOTT. CHARLES C. CONLEY.

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