US2314913A - Silk screen printing - Google Patents

Description

Pate nted Mar. 30, 1943 SILK scaEaN PRINTING Herbert A. Weiller, Los Angeles, Calif assior to Weiller Processes, Inc., a corporation or New Jersey No Drawing. Application April 17, 1949, Serial Not 33%,066

(Cit Mill-211) Claims.

My invention relates to the art of printing tlirough, a silk screen or similar foraminous material, and in particular to an improved method of preparing screens and to the use of the resulting improved screens to produce attractive stippling and crayon efiects, or effects resembling photographic prints, and to the production of multi-colored designs involving a wider range of shades and color gradation efiects than have heretofore been practical in silk screen printing.

In the practice of silk screen printing as heretofore followed for printing designs upon fabrics, paper and othersurfaces, it has been customary, after tracing the desired design upon a tightly stretched silk screen; to paint over the design area with a resist material and then completely cover the screen with a coating of enamel or lacquer to fill in the parts of the screen not covered with the resist material. The resist may be a glue size or another composition soluble in water or in another solvent that will not affect the enamel applied to the rest of the screen area. The enamel" or lacquer is of an appropriate composition that is unaffected by the resist solvent and at the same time adherent to the silk threads where it contacts them. After the enamel has dried the screen is washed with water or other solvent to remove the resist material to provide open areas in the screen through which ink or printing dyes are capable of passing during printing operations.

While this method has provided a form of silk screen stencil that is satisfactory for printing designs in {solid color without shading, such stencils have not been adapted to produce stippled or crayon efiects or shading.

Photographic processes have heretofore been relied upon to produce shading and crayon effects by applying the design to the screen by sensitizing the silk screen and exposing it to line half-tone photo-plates or to a shaded drawing on transparent material. The photographic process, however, is time consuming, tedious, ahd expensive.

In order to produce shading and crayon effects it has also been proposed to place the screen over an engraved or etched plate and then trace the desired design thereagainst with a wax crayon, the etched platev providing raised shading dots, stipple lines or other design effects. Light and dark shading is provided forby varying the pressure applied 'to the wax crayon, slight pressure producing small wax covered areas or dots-while stronger pressure produced larged areas or dots.

However, this method has the disadvantages that it is relatively expensive, requires the etching of the plate, the tedious hand operation of producing the design of wax upon the design area by means of a wax crayon, and where repetition of design is desired on the same screen, it is, for all practical purposes, humanly impossible to obtain duplicate designs and shading effects. Moreover, it is practically impossible in the hand operation to produce a stippled or dotted efiect of such fineness and degree of gradation as to make it practical to print different colors in superimppsed relation from a plurality of screens. This requires a nicety of adjustment of the'size of the ink transfer perforations in the resulting printing screen that is not practically obtainable in either of the processes above described.

According to my invention, a printing screen is provided by a relatively simple procedure and at the same time the resulting screen is capable of being used in producing novel color effects in multi-color printing.

One of the objects of my invention, therefore, is to provide a method for speedily and economically preparing silk screens for printing purposes.

Another object of my invention is to provide an improved silk screen printing stencil adapted to produce attractive stippling and crayon effects, effects similar to photographic prints and, when several such screens are used consecutively in printing, to produce multi-colored designs including a multitude of shades and color gradation effects.

A further object of my invention is to provide a method of preparing and using silk screens to produce color shading and stippling effects with different basic colors by superimposing and interspersing the colors in solid, line and stipple combinations.

The above and additional objects and advantages of my invention will become more apparent upon further consideration of the following design. This step of outlining the design with a coating of lacquer or enamel may be in some instances advantageously replaced by use of suitable mechanical stencils, the lacquer or enamel coating being later applied after the shading or stippling operation.

After outlining the design areas, the shading and stippling effect is rapidlyand effectively produced by spraying the design areas with a resist material, such as glue size, or other material which is resistant to lacquer or enamel and which is easily removable by water or other solvents; the solvent used being such as not to attack the lacquer or enamel coating. Glycerine may be added to the resist material to retard too rapid drying thereof.

The resist material is preferably sprayed. upon the screen in finely divided form, as by use of a spray gun, a stiff bristle brush filled with resist liquid and drawn over a piece of rigid material r other suitable spraying device. The resist material being sprayed in finely-divided form provides numerous small dots, the density, size and shape of which may be easily varied during the spraying operation toobtain the degree of shading desired. While solid or line effects may be painted in by a brush in the usual way, such effects may also be accomplished by skilled manipulation and adjustment of the spray nozzle.

After the resist material has been applied so as to provide the shading and stippling effects desired, the screen or at least that portion which has not been coated with lacquer orenamel is then coated so as to fill up those areas of the screen not already covered. The screen-being thus completely covered with lacquer or enamel is permitted to dry until the lacquer or enamel coating has sufficiently set for adherence to the screen. The screen is then washed in water or other suitable solvent to effect the removal of the resist material while at the same time not affecting the enamel coating adhering directly to the other parts of the screen. The resist ma terial removed leaves the screen with numerous small open areas in accordance with the shading effect obtained by the spraying operation. The screen is then ready for printing purposes. The printing is carried out in the customary way by superimposing the screen upon the fabric or other material to be printed and then forcing the ink or colored dye through the open portions of the screen by means of a squeegee or the like onto the surface to be printed.

According to another modification, the desired design is pencilled on the screen in the usual way, and then the design area is painted over with th resist material. Th remainder of the screen is then coated with enamel or lacquer, and after this is dry the resist with any lacquer superimposed or adhering thereto is washed out as with the ordinary method of making silk screen by the wash-out method. The open areas of .the screen are thensprayed with the lacquer or enamel, the spraying being so controlled as to provide the desired stipple or crayon effect. It will be appreciated that in spraying the lacquer on the design area the amount of liquid deposited will be'so controlled as to leave free areas and dots corresponding to the stippling or other printing effect desired.

According to a stillfurther modification, the design area intended to receive the stippling is outlined by coating the other parts of the screen with suitable lacquer or enamel, the open out-' lined area being thereafter sprayed with the lacquer or enamel to produce the desired stippling or crayon effect.

The use of the spray feature of my invention provides a speedy and an effective method of providing screens with stippling and shading effects. The finishedscreen resulting from the resist spraying, enameling and washing steps, contains numerous small particles or islands of hardened lacquer over the printing areas, the density and size of the particles depending, of course, upon the shading effect desired. The very fine openings thus provided also aid materially in controlling the amount of ink or dye passing through the screen during the printing operation. This feature is of great advantage where two or more screens are used in series for multi-color printing. Since the great number of very fine openings serve to restrict the amount of a particular color that may be applied to the fabric or other surface upon which the design is being printed, it becomes possible to provide two or more screens with portions of their printing areas representing overlapping portions of the same design and to use these screens in succeeding printing operations on a given fabric to print two or more basic colors in superimposed and interspersed relation without danger of flushing." By stippling different colors in superimposed and interspersed relation, a large variety of colors and attractive color shading effects are made possible. I

In multi-color printing a screen is prepared for each basic color, that is, the design is sprayed with resist material in accordance with the amount and denseness of that. particular color desired. One of the many advantages of my method in multi-color printing lies in the fact that each screen used for a basic color may be made without shading the stippling effect; that is, the stippling effect may be prepared by a substantially uniform spraying operation, the solid, line and shading effects being produced by superimposing and interspersing the basic colors. By using a series of screens thus prepared, the different colored dots or areas produced may be superimposed, interspersed or both, thereby producing a great variety of colors and color gradient effects. I find that the finely perforated printing areas prepared in accordance with the spray feature of my invention render it possible to apply colors more lightly, thereby enabling the freshly printed cloth to dry rapidly and quickly reach a condition for receiving a second color. This feature thus makes for more rapid printing without the danger of flushing.

It will be understood that when I have herein referred to basic color, this term has reference to any desired color for which a screen is prepared, whether the color is one of the primary colors of the spectrum, one of the hues thereof, or a tint produced by blending certain of these colors or hues and/or the inclusion of black and white.

It will also be understood that where I have herein referred to a silk screen," this term is to include not only silk but also other suitable fabrics or foraminous material that will permit the ink to pass and that is resistant to the solvents employed in the washing-out step and also is resistant to the dyes or ink used in the printing operation.

While I have described a form of my invention and several, variations thereof, I am aware that many additional variations thereof are possible, and for that reason it is to be understood that the forms of my invention herein described are to be regarded as illustrative thereof and not as limiting the appended claims.

I claim: I

1. The process of multi-color printing with silk screens which comprises providing a plurality of foraminous screens each one for each color and each having a selected portion of a desired design sketched thereon that is to appear in the corresponding color and so arranged that at least a portion of the design in one color will overlap at least a portion of the design in another color when the screens are used in printing the desired design, spraying a coating material in finely divided form on said selected portions of said foraminous screens to form numerous dots therecn in a varying arrangement characteristic of sprayed material, controlling the denseness of the varying sized and shaped dots during the said spraying operation for a given screen in accordance with the wish of the operator to achieve the color effect desired to be produced by each screen, and thereafter printing a multi-color design upon a surface to be printed by successively forcing a corresponding color through the openings of each different screen upon said surface.

2. The process of multi-color printing with silk screens which comprises providing a plurality of ioraminous screens one 'for each color and each having an outlined area corresponding to one ly divided form upon the said outlined areas of said screens to form numerous dots thereon in a varying arrangement characteristic of sprayed material, controlling the denseness of the varying sized and shaped dots during the said spraying operation for a given screen in accordance with the wish of the operator to achieve the color effect desired to be produced by each screen,- coating the parts of the screens disposed outside the sketched areas with lacquer and printing a multi-colored design upon a surface by successively forcing a corresponding color through the openings in each different'screen upon saidsurface.

4. The process of multi-color printing with silk screens which comprises providing a plurality of ioraminous screens one for each color and each having a selected portion of a design sketched thereon that is to appear in the corresponding color and so arranged that at least a portion of the design in one color overlaps that of another when the screens are in superposed relation, coating the screens except for the sketched areas with a lacquer, thereafter spraying a lacquer in finely color and so arranged that at least a, portion of the outlined area in one color overlaps that of another when the screens are in superposed relation, coating the screens except for the outlined areas with a lacquer, spraying a lacquer resistant material in finely divided form upon the said outlined areas of said screens to form numerous dots thereon in a varying arrangement characteristic of sprayed material, controlling the denseness of the varying sized and shaped dots during the said spraying operation for a given screen in accordance with the wish of the operator to achieve the color effect desired to be. produced by each screen, coating the sprayed areas of each screen with lacquer, removing the lacquer resistant material and any of the lacquer superimposed thereon to provide open screen areas, and printing a. multi-colored design upon the surface by successively forcing a corresponding color through the openings of each different screen upon said surface.

3. The process of multi-color printing with silk screens which comprises providing a plurality of forarninous screens one for each color, sketching an outline of a desired design to form an area in each screen corresponding to the color to be printed by that screen and arranging the areas so that at least a portion of the design in one color overlaps that of another when the screens are in superposed relation, spraying a lacquer in finedivided form upon the said sketched areas of said screens to form numerous dots thereon in a varying arrangement characteristic of sprayed mate-' after printing a multi-colored design upon a surface by successively forcing a corresponding color through the openings in each different screen.

5. The process of multi-color printing with silk screens which comprises providing a plurality of foraminous screens one for each color, covering each screen with a stencil whereby only that part of each screen is exposed which is to be the printing area and which is to appear in the color corresponding to that screen, said areas being so arranged that at least a part of the area of one color overlaps that of another when the screens are in superposed relation, spraying a glue size in finely divided form upon the exposed areas of said screens to form numerous dots thereon in a varying arrangement characteristic of sprayed material, controlling the denseness of the varyingly sized and shaped, dots during the said spraying operation for a given screen in accordance with the wish of the operator to achieve the color effect desired to be produced by each screen, removing the stencils and coating the screens with a lacquer, washing the screens in water or other solvent which is not injurious to the lacquer but which is capable of removing the glue size, and printing upon a surface with a plurality of colors by forcing a different color through the openings in each different screen successively.

HERBERT A. WEILLER.

I CERTIFICATE or omorrow. ratent No. 2,51h,915. March 50, 19

HERBERT A mime? It is hereoy certified thet error appears in the printed specification of the above numbered. patent requiring'correction as'follows: Page l, eecond column, 'line 2, for 'lerged" read --larger--; page 5, first colmnn-, li-ne-7,-cla1m 1, after the word "screens" strike out --each--; line 14.0,

claim 2, ,for "Varying" read-varyingly--; line 141;, claim 2, for "areas" read area-- "and second column, line 14., claim 5, for varying readr m u; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the cage in the Patent Office. v Signed and sealed this 11th day of May, A. 1), 191m.

} Henry Van Arsdale, (Seal) ecting Commissioner of Patents.