US2166367A - Process for the production of metallic screens - Google Patents

Description

July 18, 1939. E. o. NORRIS PROCESS FOR THE PRODUCTION OF METALLIC SCREENS Original Filed Dec. 6, 1954 3 Sheets-Sheet 1 IN VEN TOR WWAA'W A TTORNEYS July 18, 1939. NORRIS 2,166,367

PROCESS FOR THE PRODUCTION OF METALLIC SCREENS Original Filed Dec. 6, 1934 3 Sheets-Sheet 2 INVENTOR WW M ATTORNEYS July 18, 1939.

E. o. NORRIS 2,166,367

PROCESS FOR THE PRODUCTION OF METALLIC SCREENS Original Filed Dec. 6, 1934 5 Sheets-Sheet 3 INVENTOR WQ/dv QM,

A TTORJVE VJ tented July 18, 1939 NM -F CE Iron m raonoorron or a mar time scanners 'Edward OmarNorrIa-We ItpoI-t, Coma, auig nor to. Edward 0. Norris, Ina,

. peorporation of New York strengthen a, 1934, Serial No. maze New York; N. Y.,

* a BoueIedDecember 14,103: 150mm (01. 204-4) This invention relates to metallic screens and to. the formation thereof; and to correlated improvementsand discoveries appertaining thereto. An object of the invention is to provide an improved metallic screen. I

More specifically it is an object of the invention to' provide metallic screens having advantageous properties when compared to wire mesh or Punched-screens. f j

Another object is the provision of particularly fine-mesh screens of advantageous character.

Another object is to provide a matrix from which improved screens may be effectively formed. 7

Another object isthe provision of an improved process for the provision of a matrix for screen formation.

Other objectsof the invention will in part be obvious and will in part appear hereinafter,

The invention accordingly comprises the several steps and the relation of one or more of such steps with respect to each of the others, and the article possessing the features, properties and the relation of elements, which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims. r

For a fuller understanding of the nature and objects of the invention reference should be had to the following detailed description taken in conthe accompanying drawings, in

in the development of said device;

- Fig. 10 is a. similar view of a screen'formed on g rlid gartially removedfrom the matrix shown in Figs, llthrough 17 are-similar views of a modiflcation of the device shown in Fig.- 1 and shown in successive steps in the development thereof; I

Figs. 18 and 19 are similar views of a modification of the matrix'show'n in Fig.1? and showing successive steps in the development of said modification; I i r i Figs. 20 and 21 are sectional views in elevation of the matrix shown in Fig. 19 as a screen is being formedthereon;

, Fig. 22 is' a perspectivview of a'screen' partially removed from the matrix shown in Fig. 19;

Fig. 23 is similar to Fig. 21 and shows a modification of the step shown in Fig. 21;

Fig, 24 is a plan view of a screen made by a method including the step shown in Fig. 23; and

Fig. 25 is across section in elevation of the I screen shown in Fig. 24 taken along the line 2%". a

The use of mesh screens, especially for fine work, is subject to many disadvantages, among which is the tendency for particles just largelo enough so that they do not pass through thescreen to lodge above the openings in the screen. There are, moreover, practical limitations to the fineness of mesh which can be produced and used commercially. For this reason non-metallic screens arere- 1 lied on for many purposes for which metallic screens would otherwise be better adapted, or in which metallic screens would have a much longer life, An example of this is the use of bolting cloth in the sifting of flour. For relatively coarse work 20 mesh screens are still used for many purposes in connection with which screens of the character contemplated by the invention would have definite advantages. There are also many instances wherein a flat screen having a large percentage of 25 There is furthermore a considerable need for 80 metallic stencils wherein the openings" instead of being entirely cut away are composed of a metallic portion with fine, substantially uniform, holes throughout the extent of the openings.

In screen printing processes atthe present time silk screens are utilized because of the lack of any available satisfactory metallic screen. The use of a silk screen, however, involves a careful and time-consuming operation of blocking out all portions which it is not desired to print, and also 40 issubiect to difllculties because of the lack of strength of silk screens.

With a view to overcoming the foregoing and other diflieulties, the present invention is directed to the provision of a screen having a smooth up- 4-5 per surface with a large number of closely-spaced holes therethrough, and of a stencil having, besides solid portions, non-solid portions with a smooth upper surface and with a large number of closely-spaced holes therethrough. Inacproduced electrolytically, preferably metal de- 2 amass? 8 ordinarymetallicsheetssuchasrolledordrawn sheets. This may be due to a uniformity of thickness throughout the sheet, or uniformity of the internal structure of the sheet, or to a uniformity intheresistancetoanetchingactionbutatall l0 eventsvariationsinthetimeinwhichthedifierent holes etch through is markedly reduced. It is tobeobservedinthisconnectionthatwberea plurality of holesis being etched from a sheet in an etching bath, and where one of these holes llisetchedthroughbeforetheothentheetching chemical exerts a sidewise etching on the first hole so as to make it larger than the other holes. It is found possible to produce larger metallic sheets of rigorously uniform thinness by electrodeposition than by other methods.

' By way of example there is exemplified below one specific type of procedure which may be utilined in the formation of a matrix for the production of screens of the character above indicated.

' A thin sheet I! of metal such as copper is thoroughly cleaned and fastened to a fiat surface such as a glass plate, as with adhesive tape. The thickness of the sheet may be about five-thousandth! of an inch (0.005"). The sheet should have a I) uniform thickness, and for this purpose electrolytic metal, such as electrolytic copper, is desirable. In order to provide a sheet having a smooth, uncrinkled surface, the sheet may be formed by plating copper on a sheet of commercial electro- 0l lytic copper two-thousandths of an inch (0.002") thick.

An etch-resistant design is applied to a face of the sheet in any suitable fashion. The following is one method of doing so: The sheet is polished a and coated with a sensitised glue solution of any suitable nature. One such solution which may be utilised may be formed by mixing '1 ounces (avoirdupois) of clarified glue with 16 fluid ounces of water, 6 drama of ammonium bfchromate, the al- 5 bumen of 8 eggs, and 8 drops of ammonia. After application, the glue solution is drained from the sheet, and the sheet dried over a source of heat. It is thereupon put in a vacuum frame under a fiat-screen negative embodying opaque dots sep- Q arated by interconnected clear lines, and exposed to are light or sunlight'for five or ten minutes. It is then immersed in a water solution of methyl violet and washed out in clear water. After drying, the screen print may be examined under a a; magnifying glass for faults, and if any are found, these may be corrected by handwork. The print is thereupon heated over a gas fiame until the print is burned to a dark brown. The design superimposed upon the metal sheet is, in the case described, a network of intersecting lines ii of developed glue (see Fig. l). I

After the formation of a screen design on the sheet by the foregoing or other suitable method, or at a previous time, the sheet is coated on the as back with a protective material it, for instance.

shellac, and dried. In order to enable the operator to assure himself that the shellac completely covers the sheet, tinted shellac may be used. The printed and protected sheet is immersed in an 70 etching solution, such for instance as ferric chloride, to form depressions II in sheet ll (see Fig. 2) between the lines of the print throughout the sheet. After etching to a suitable depth, depending upon the height and physical properties of 15 certain protuberances described below, the sheet iswaahedandthoroughlycieanedmsbyamix ture of common salt and vinegar. Aftcrthesheet isdriedtheetchedsideiscovered withanonconducting, semi-liquid material ll, which will adheretotheetchedsurfaceandwhichwillnot I .be attacked by a subsequent etching solution. An

acid-resistant paint, for example, that known under the trade name of Ce-Oo Super-Chemical Resistant Finish, may be used. The term "nonconducting material, used in this connection 1. throughout the specification .and claims, is intendai to include not only materials of high electrical resistivity but also those materials, even of low resistivity, onto which it is difficult to electroplate. Excess material is removed with a squeegee is so as to leave the surface of the depressions covered with material as in Pig. 3. The covered surface is then immediately dusted over with a finelydivided. granular conductive material II, such as copper powder, and allowed to dry for five or six U hours (see Fig. 4)

The intersecting cross ridges ll of developed glue are removed, for example, by sandpapering, and the remainder of the surface scrubbed to remove all metal powder which does not actually I adhere to the non-conductive materiaHsee Pig. 5). The surface thus formed is then plated with metallic material ll, such as copper, to a depth of, for instance, about four-thousandths (0.004) or five-thousandths (0.005) of an inch (see Fig. I 6). The copper powder or other granular material assists in holding the deposited material firmly on the non-conductive material. Thereafter the shellac I! on the unetched side of the plate is removed with alcohol, and the plated side coated II with shellac II, or other protective material, which is allowed to dry (see Fig. 'l). The plate is then immersed in an etching bath which eats into the original metal to form a matrix having protuberances of non-conductive material and intercona nected valleys where the metallic material is exposed as shown in Fig. 8. Fig. 9 is a view of the matrix shown in Fig. 8, but viewed from below.

In order to provide an effective matrix, the protuberances preferably should not be substantially as less than one-thousandth (0.001) of an inch in height.

Any equivalent process may be substituted for the etching bath mentioned above. For example,

. the original matrix may be removed'by abrasion w or sand blasting or by electro-corrosion in a conducting bath. The term etching in the specification and claims is accordingly not to be limited to the action of a solvent upon a soluble solid.

Instead of the print of intersecting lines shown as on the metallic sheet in Fig. l, a print of raised, spaced elements may be applied as a design to a suitable surface and a casting made therefrom of some low-meltlng-point material such as wax.

In the interstices or depressions of this casting a so non-conducting materialis inserted preferably as aliquid. A conducting powder is sprinkled over one face of the casting and the spaced quantities of non-conducting material, which latter is permitted to harden. A layer of the metal is then 06 electroplated upon the conducting powder and the wax melted away leaving a matrix similar to that shown in Fig. 0, except for the coat of shellac In certain instances there is a tendency for a 70 screen plated on such a matrix to stick occasionally in spots and to leave portions of its body on the matrix when stripped therefrom. In order to permit these portions to be readily removed by etching, the valleys in the matrix may be plated 7i amass-r with an etch-resistant coating of suitable materi such as platinum, which may be applied by plating a thin layer over these portions. By way of example, there are described below several processes whereby a screen may be formed electrolytically on a matrix having protuberances which present anon-conductive surface such as is described above.

There may be provided on the matrix a film l8 ofmaterial which will maintain electro-deposlted material as an independent layer and facilitate stripping of electro-deposited material from the matrix. Such a film may be formed on the matrix itself as by oxidation or other suitable process, or may be provided by a material supplied thereto. At all events the film should be thin enough and of such character as not to interfere materially with the'electro-deposition of material on the metallic portions of the matrix. One procedure which may be utilized is to flow a thin mixture of beeswax and naphtha over it and allow it to dry. The matrix is then placed as an anode in a suitable plating solution, such, for instance, as a copper bath, and metal electro-deposited on the metallic valleys in the matrix, there being, if desired, the stripping facilitating film described above, between the metal forming the valleys of the matrix and the lastmentioned metal, which last-mentioned electrodeposited metal is to comprise the desired screen. The latter may be built up to any desired thickness and the deposit It! thus formed stripped from the matrix as shown in Fig. 10. If the electro-cleposition is stopped at a point where the deposit is well below the tops of the protuberances there is provided a thin screen of satisfactory quality. When a thicker screen is desired the deposition may be carried to a point where it almost reaches the top of the protuberances. The deposited material is then stripped off and the top and bottom surfaces thereof run on a roller which applies an acid-resistant type of stencilling paste, e. g., du Pont's black stencilling paste, or of printing ink thereto. The sheet which has been stripped off is then immersed in an etching bath. The ink acts toprevent etching of the upper surfaces, but the contiguous projections at the top of the deposit are quickly cut away so that the holes are of the desired shape. Another procedure which may be utilized is to carry the plating to a point where the deposited metal entirely covers the protuberances. This will result in upward bulges on the lines between the protuberances, with thin portions over the protuberances. After stripping, the lower points on the deposited material may be given a coat of etch-resisting material such as printer's ink and the back covered with shellac and the stripped sheet then immersed in an etching bath which will cut through the thin portions which are formed over the protuberances.

In certain instances it may be desirable to spread over the wax a very thin coat of graphite of very low conductivity.

It will be apparent that a procedure such as.

described will result in the provision of a highly satisfactory screen for many purposes, and, when the protuberances are properly spaced and of proper height, will result in the production of a screen embodying, the feature of the invention wherein the land of the screen is deeper than the distance between adjacent holes.

Materials which are highly desirable for use in providing the protuberances in matrices are synthetic rubber compositions, such, for instance, as those synthesized from acetylene. example of such a composition is the material found on the market under the trade name Duprene". Such material is in general resistant to etching chemicals and has sumcient cohesion to insure against breaking when an electro-deposited screen is stripped oil.

In certain instances it is desirable to provide a particularly thick screenfiand for such use a material such as indicated above may be effectively used.

Deep matrices adapted for formation of thick screens may be formed by the procedure exemplifled below.

A thin sheet of electrolytic copper, preferably electro-deposited in a thin sheet which may be less than 0.0030 of an inch thick and which is preferably less than 0.0015 of an inch thick, is attached, as by adhesive tape, at the edges to a flat plate of suitable material such as plate-glass. In certain instances it may be advisable to reduce further the thickness of the original electro-deposited sheet. This may be accomplished in any convenient fashion, as by grinding or electro-corrosion. It is preferably carried out by etching which gives an especially even surface. Splash and spray etching are particularly effective. The screen is then cleaned and treated for printing, as by being coated with a sensitized glue solution and dried as described above. Thereupon, it is subjected to a suitable printing process which may be similar to that above described in connection with Fig. 1 and removed from the glass plate. The back of the plate (the face opposite to the face treated with glue) is thereupon given a thick coat of shellac which in this instance is allowed to dry only partially. The sheet is next spread upon a glass plate 20 again with the tacky film 12a of shellac against the plate, and immersed in an etching solution (e. g.. ferric chloride) until the portions from which the unexposed glue has been washed, etch completely through the sheet, as shown in Fig. 11. Alcohol, carried in this case, in the partiallydry shellac, acts to retard the etching of those holes which etch through first, and to prevent the usual tendency for certain of the holes to be etched radially outward from their respective axes to a greater extent than the others. The evenness of the alcohol layer appears to be a contributing factor in obtaining a uniform etch. A screen, as formed; above, is exemplified in Fig. 12. A screen formed in this manner is desirable for a number of uses without further treatment. In order to form a matrix, or a thicker screen, however, the screen shown in Fig. 12, after being thoroughly cleaned, is electroplated on all sides with copper to build up a screen such as shown in Fig. 13. It is then rolled with an acid-proof ink 2|, stencilling paste or other etch-resisting material, on bothfaces and again etched to reduce the width of the land, providing a screen as shown in Fig. 14. The foregoing plating and etching procedure is repeated until a thick screen without an undue amount of land is provided. In certain cases it may not be necessary to etch out the perforations after additional metal has been deposited upon the screen, as it has been found that under certain conditions the metal is deposited principally upon the faces of the sheet with little or no deposit on the surfaces of the perforations. This screen likewise is desirable itself for various uses.

.usedasanintermediateproduct surface. The screen shows in Fig.1

in A nlitable cover,

tion of a deep matrix. such, forinstance,a.sa eceolpaperflmadetacky with glue, is secured to the side of the screen where the holes are smallest. and the holes on the other side are filled with synthetic rubberllke material or other .desirable non-oonductini material a. The synthetic rubber-like material may be cut with naphtha and poured in. The surface of the sheet is immediately dusted over with copper, sine or other suitable conducting material 21 in granular form. The appearance of the matrix at this stale isilhmtrat edin Fig. 15. After the naphtha has dried out, the glued paper is removed and the screen subjected to a relatively high temperature, e. g., 250' R, for about three hours to vulcanise the rubber compound. After vulcanization the side of the screen which carried the glued paper is protected and the other side smoothed off to the original metal. The protection may be accomplished by providing a coat 2 of shellac, and the removal may be accomplished by rubbing with fine sandpaper. Thereupon metal, e. g. copper, is electro-deposited on the granular material and on the cleaned metal (see Fig. 16) to provide a sheet 20. The granular material serves to secure the deposited and the non-conducting material firmly together. The shellac is then washed off the original sheet and the face of the deposited metal protected, as by a coat of shellac. The sheet is then etched to cut away the original metallic material between the rubber protuberances to provide a finished matrix as shown in Hg. 11. By procedures such as described above, screens of particular thickness may be readily formed on this matrix.

Under certain circumstances it is desirable to utilize the screen shown in rigs. 12 or 14 as a master screen to produce a matrix for the screens by a method which is a modification of the above method. A suitable cover such as apiece of paper 22, made tacky with glue, is secured to the side of the screen when the holes are smallest and the holes in the screen'are filled from the side on which they are larger with a synthetic rubber-like material or other desirable non-conducting material 23. This material is also spread entirely over the face opposite the paper If. as, shown in Fig. 18; The paper I! is then taken off and the metal I. removed in any suitable fashion as byetching, so as to leave a matrix 21 having a back It and protuberances It all of non-conducting material as shown in Fig. 19.

The troughs between the protuberances are caused to become conducting surfaces. This may be accomplished by dusting with a metallic powder 80, which latter may better adhere to the surface by first applying a sticky wax solution II to the surface (see Fig. 20). The metallic powder may beremoved from the tops of the protuberances by rolling up" the matrix with a greasy ink. The powder remaining is connected to one electrode in an electrolyte and the device is then ready to act as a matrix for the deposit thereon of a screen. When a screen 82 has been deposited (see Fig. 21) on the matrix to the desired dept-h it may be removed by stripping it (see Fig. 22) from the matrix.

Thetroughsmayalsoberendsredconducting by any other convenient method, for example, by precipitating a metal such as silver on the surface of the non-conducting material and rolling thetopsoftheprotuberanceswith agreasyink.

The eiectrodeposit of the screen I! in Fig. 21 is facilitated by slowly immersing the matrix into the electrolyte, the portion of the matrix farthest removed from the attached electrode going into the bath first. The rate of immersion is sufiiciently slow to allow a relatively small area to have atdeast a very thin uniform layer deposited thereon before the adjacent area is immersed. In order that the entire matrix may be covered with a deposit of uniform thickness the end of the matrix which is immersed first may be removed from the electrolyte first, the rate of passage into and. out of the electrolyte being constant.

It should be noted that for purposes of clarity the dimensions in the drawings are exaggerated and particularly the dimension which gives the height of the protuberances. Screens made according to the methods described herein sometimes have 250,000 perforations per square inch.

If the screen builds up in little collars or cones about the protuberances, these collars may be removed from the screen by grinding and etching.

The inking step may be omitted before the electro-deposition. Instead, after deposition has been begun, the deposited metal 32 may be rolled a up" with a greasy ink 33 which will adhere only to the tops, or tops and part way down the sides, of the metal protuberances. The deposit is then continued whereby only the troughs become more deeply inlaid with metal. After stripping the screen from the matrix and washing off the ink, a relatively slight etching will remove the relatively small amount of metal first deposited on the tops of the matrix protuberances and will leave the desired screen with perforations extending therethrough.

In case the last-mentioned etching is carried out over a predeterminedly designed portion 34 of the screen, the final screen forms a stencil of the type used in silk screen" printing with perforations 38 from one face of the screen to the other only within the boundaries-of the portion 34, as shown in Figs. 24 and 25. Such a screen made from a deep matrix like that shown in Fig. 19 from the process described in connection with n Fig. 14 is particularly strong and effective although any of the methods described above for securing the vertical-sided depressions on one side of the screen may be utilized.

Since certain changes in carrying out the above process, and certain modifications in the article which embody the invention may be made without departing from its scope, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be Q interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein de- .5 scribed, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Having described my invention, what I claim as new and desire to secure by Letters Patent, is: 7

l. The process of making a screen, comprising electro-depositing a sheet of material in a layer on a matrix which has protuberances to a depth whereby said protuberances are at least substantiallycoveredbythedepositremovingtheu amass-r deposited material from said matrix as a sheet having depressions on one face thereof corresponding to said protuberances and removing a portion of the other face of said sheet opposite to the face having. said depressions to adepth such that certain of said depressions are reached.

2. The process of making a screen, comprising forming a master screen, filling the interstices of said master screen with non-conducting material, providing-a back common to the material in said interstices, removing said master screen and applying a conducting surface to said nonconducting material, electro-depositing a sheet of metal in a layer on said conducting surface, removing said metal as a sheet having depressions on one face thereof corresponding to the shape of said non-conducting material and removing a portion of the other face of said sheet opposite to the facehaving said depressions to a depth such that certain of said depressions are reached.

3. A matrix for the electro-depcsition of a metallic screen of the type described comprising a plurality of spaced bodies of non-conductingmaterial supported by a backing sheet of metal, the said spaced bodies being protuberant 'and of substantial height and united to said backing sheet by electro-deposition.

4. The process of producing an electrolytically deposited screen, the land thickness of which bears a ratio to the land width substantially greater than that which would result from electrolytic deposit merely on an unconfined conducting area conforming to the pattern of the screen to be produced, which said process comprises providing a matrix the exposure surface of which includes a conducting area and nonconducting bodies projecting therefrom, said nonconducting bodies being composed of material of rubber-like resilience and being of substantial height for limiting lateral spread of an electrolytic deposit on the conducting area, then laying on said conducting surface an electrolytic deposit of the desired thickness, and then stripping the deposit from the matrix.

5. Process of producing an electrolytically deposited screen, the land thickness of which bears a ratio to the land width substantially greater than that which would result from electrolytic deposition merely on an unconfined conducting I area conforming to the pattern of the screen to be produced, which said process comprises providing a matrix the exposure surface of which comprises a conducting area and non-conducting.

bodies projecting therefrom for limiting lateral spread of an electrolytic deposit on the conducting area, said non-conducting bodies being of substantial height and diminishing in cross-section area as the height increases, then laying on said conducting area an electrolytic deposit of the desired thickness, and then stripping the deposit from the matrix.

6. The process of producing an electrolytically deposited screen of a predetermined pattern,

* minimum and maximum land widths and hole dimensions, the land thickness of which bears a predetermined ratio to the said minimum land width substantially greater than that which would result from electrolytic deposition merely on an unconfined conducting area conforming to the said predetermined screen pattern and of the said predetermined minimum land width, which said process comprises providing a matrix the exposure surface of which comprises a conducting area of a pattern conforming to the predetermined screen pattern and of the minimum width dimension ofthe lands of thescreen to be produced, and also comprises means for limiting lateral spread of an electrolytic deposit on the said conducting area comprising cores of nonconducting material constituting non-conducting areas of said exposure surface and projecting to a height above said conducting areas at least substantially equal to that of the land thickness of the screen to be deposited and of a section progressively diminishing as the height increases, then laying on said conducting surface an electrolytic deposit of the said land thickness, and then stripping the deposit from the matrix.

7. .A matrix of the type described, comprising a plurality of spaced bodies of material presenting a surface inactive to electrolytic deposition and supported by and aiilxed to a backing sheet presenting a conductive surface, the said spaced bodies being protuberant and projected from said conductive surface to a substantial height and diminishing in cross-section area as the height increases.

8. A process of screen formation, which comprises imposing an etch-resistant material upon a metal sheet in a design, etching said sheet away completely through between the faces thereof where not covered by said design, removing said material, inserting material presenting a surface inactive to electrolytic deposition in the spaces which have been etched out, coating one face of said sheet with conducting material, electro-depositing a reinforcing metal backing on the said face, removing the metal on the opposite face of said sheet uniformly-to a depth that permits the material in said spaces to project, applying to the said opposite face a separating film which will not prevent electro-deposition, building up a deposit on said opposite face by electro-deposition on those portions of the same not covered by said material in said spaces and stripping said deposit away as a screen.

9. In a process of screen formation, the steps which comprise applying an etch-resistant material to a sheet in the form of a design to a sheet of conducting material, etching away said sheet completely through between the faces thereof where not covered by said design whereby perforations are formed, removing said etch-resistant material, filling said perforations with material presenting a surface inactive to electrolytic deposition, reinforcing said sheet by applying thereto a backing of conducting material and removing at least a portion of the metal from the opposite side of the sheet to a uniform depth over the surface thereof and to a depth sufficient to allow the material in said perforations to project beyond the surface of said sheet.

10. A matrix of the type described, comprising a plurality of spaced bodies of material having a rubber-like resilience and presenting a surface inactive to electrolytic deposition supported by and aiiixed to a backing sheet of metal, the said spaced bodies being protuberant and of substantial height.

11. A matrix for the electro-deposition of a foraminous sheet, comprising a plurality of bodies of material presenting a surface inactive to electrolytic deposition and supported by a backing sheet presenting a conducting surface, the said spaced bodies being arranged in predetermined positional relationship and being protuberant and projecting from said conducting surcross-sectional areas as the height increases.

ll."lheproessotprodueingamatrlxtorthe productionoisnslectro depositedscrmstencil, andthelike.whichcomprisesiillingwithmaterialpresentingasurisce inactivetoelectrolytic depositiontheperiontionsotioramincussheetoi iirstmcntionedmaterialprotuherantandoisuhstantialheight. I

13.!heprocemotpmdudngamatrixiorthe production olanelectro-deposited screen. stencil andthelike.whichcomprisesflllingthe perforations or toraminom sheet of electrically conductive material with material presenting a surtaoe inactivetcelectrolytic deposition and apnly lan adherentcoatingtoonesurlaceolssid sheet and totheexposedareasoithematerialinsaidper- Iorations.

14.!heprocess ofproducingamatrlx iorthe production of an electro-deposited screen, stencilandthelike,whlchcomprlsesiillingtheper- Iorstions of ioraminom metal sheet with materialpresentingasurtaocinactivs'toelectrolytic arm toone o! deposition mum an adherent coating surface of said sheet and to the exposed the material in said perforations and removing tromtheexposedmetallicareasoitheotherisc otsaidsheetenoughmetaltocamethematcrial in said periorations to project beyond said metallic areas. 4

15. The process of producing a matrix (or the production oi an electro-deposited screen. stencil and the like, which comprises filling the perforations of ioraminous sheet .0! electrically conductive material with material presenting a surface inactive to electrolytic deposition applying to one surface of said sheet and to the exposed areas oi material in said perlorations an adherent coating entirely covering the same, and removing to a uniform depth from the electrically conductive areas 0! the other face of said sheet enough material to cause the materialin said periorations to project beyond said areas of electrim cally conductive material.

EDWARD OMAR NORRIS.

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