US2557352A

US2557352A - Printing stencil

Info

Publication number: US2557352A
Application number: US742615A
Authority: US
Inventors: Kanitz George
Original assignee: Individual
Current assignee: Individual
Priority date: 1947-04-19
Filing date: 1947-04-19
Publication date: 1951-06-19
Anticipated expiration: 1968-06-19

Description

June 19, 1951 n-z 2,557,352

PRINTING STENCIL Filed April 19, 1947 m l v I O t\\ 0 I o 1 I N o INVENTOR.

4 GEORGES KANITZ BY J M Patented June 19, 1951 UNITED STATES PATENT OFFICE PRINTING STENCIL Georges Kanitz, Caracas, Venezuela Application April 19, 1947, Serial N0. 742,615

6 Claims. (01. 101-1282) This invention relates to new and improved printing stencils and has particular relation to new and improved stencils adapted to be used in the so-called screen process and to a method of preparing such stencils.

The main object of my present invention is to provide a stencil for the screen process, which shows a true and exact reproduction of the design to be printed and can be easily and conveniently produced.

Another object of my present invention is to provide a stencil for screen process-printing by copying the design directly to the stencil layer without the disadvantage of the so-called mesh-marks.

A further object of this invention is to produce a stencil for screen process-printing by first providing the screen with a suitable layer which is not sensitive to light, applying the design to be printed directly to this layer which is subsequent- 1y rendered sensitive to light and then insoluble by exposure to light but only in those portions of the same which are not covered by the design, whereupon the soluble portions of said layer, which are covered by the design and the design proper are removed by dissolution of the soluble portions of the stencil layer and the stencil is ready for use.

Other objects and theadvantages of the invention will be apparent from the following specification and claims and the appended drawings which illustrate, by way of example, some preferred embodiments of the invention, and in which Figure 1 illustrates diagrammatically in top view a stencil embodying the present invention;

Figure 2 is a sectional view along line 2-2 of Figure l; I

Figure 3 illustrates a part of Figure 2 on an enlarged scale before developing, and Figure 4 is a view similar to that of Figure 3, after developing.

. Referring now to the drawings in detail, I is a square frame, which may consist of wood or metal, and to which a silk screen 2 of the customary type is applied by stretching in the usual manner. 3 denotes a design, and 4 denotes the material of the stencil before, and 5, after, the developing step.

In carrying out my invention, the solution of a suitable transparent, colloid material, for example an aqueous solution of glue or gelatine is applied to the screen in order to fill the holes of the screen and form a layer of about 0.3 to 0.5 mm. thickness. The coated screen is dried at a temperature of, for example, 15 to 25 0., and is then brought in contact with the original design to be reproduced and a reproduction is produced on the surface of the dried colloid layer by painting or drawing, as indicated in Figures 1 and 2. The design may be of any type, i. e. it may, for example, consist of printed types or a drawing or the like. In preparing the design to be reproduced on the stencil layer, I prefer the use of inks, pigments or drawing crayons or the like, which are impermeable to light. After the said reproduction on the stencil layer has been made and dried, said layer is treated with a hardening or sensitizing solution, for example an aqueous 24% solution of ammonium bichromate and then dried, in order to render the stencil layer substantially uniformly sensitive to light. If a sensitizing solution has been used, the surface of the stencil layer, which carries the reproduced design, is now exposed to a strong light source and after sufiicient exposure, developed with warm water. During this developing, those portions of the stencil which are covered by the design and, therefore, have not been affected by the exposure to light, are dissolved, and the drawing adhering to these portions, is also removed from the stencil, thus leaving screen holes forming a registering design, open as indicated in Fig. 4. In contrast to this, those portions of the stencil which were not protected from light by the design and became hardened and insoluble by the exposure to light are not removed by water. They adhere to the screen and keep the holes thereof sealed. Thus, after developing and drying, the stencil is ready for use.

According to a modification of my invention, reproduction of the design to be printed may be produced on the stencil layer by means of inks or lacquers or the like, which are permeable to light but impermeable to the sensitizing solution. After the reproduction of the design to be printed on a surface of the stencil layer by means of an ink or other material of the before-mentioned type, the surface bearing the reproduced design.

is treated with a sensitizing solution, and, after drawing, said surface is exposed to light and then developed with warm water. Owing to the fact that the ink or the like used in reproducing the design is impermeable to the sensitizing solution,

the portions of the stencil layer covered by the design are not sensitized and not affected by the exposure. These portions and the design covering them, are, therefore, removed by the developing step. The developed stencil is dried and is, then ready for printing.

According to another embodiment of my invention, developing of the stencil layer is effected by means of a solution which is capable of hardening and rendering substantially insoluble or diflicultly soluble the material of the stencil layer. In using such a hardening solution, the design is applied in a manner substantially identical to that described above, but by means of an ink or the like which is impermeable to said hardening solution. After application of the design to the stencil layer, the surface of the latter, which carries the design, is treated with a suitable hardening solution and then permitted to dry. In this trea ment, those portions of the stencil layer which are permeated by the solution become insoluble or difficultly soluble. After drying, those parts of the stencil layer which have been protected from the hardening solution by the impermeable design are dissolved by means of a solvent, for example, moderately warm water, and are thus removed together with the design.

According to my invention the screen is completely filled with the stencil material prior to the reproduction of the design on it. I prepare the reproduction on a substantially smooth surface and obtain sharp contour lines substantially without any mesh-marks. Furthermore, in contrast to prior processes, I can use stencil layers of considerable thickness, which completely fill the holes of the screen, or may even form a thicker the stencil layer prior to sensitizing or harden- 1'1:

ing, the lines of the design are in intimate contact with the stencil layer. This results in true and exact reproductions and greatly facilitates true reproduction of fine details.

It will be apparent that my present invention is not limited to the specific details and steps disclosed and may be carried out with various modifications. For example, instead of the above described solution of glue or gelatine, other colloid solutions which are adapted to form a transparent layer substantially without the formation of bubbles and can be sensitized to light, and other sensitizing solutions and various hardening solutions may be used. For example, layers of fish glue or gelatin may be hardened and rendered insoluble by the action of a 56% aqueous solution of chrome alum, or a aqueous formaldehyde solution, or an aqueous solution containing about 40% formaldehyde and about 5% phenol. As further examples of stencil materials, shellac, collodium, fish glue and transparent synthetic plastics, and as examples of other sensitizing solutions, other compounds of chromium, such as potassium bichromate may be mentioned. These and other modifications may be made Without departing from the spirit and scope of the invention as defined in the appended claims.

The term design is used in the present specification and claims to denote the letters, words, drawings or the like to be printed.

What I claim is:

1. A process for preparing stencils for screen printing, said process comprising providing a stretched screen with a soluble stencil layer insensitive to light, applying a design to be printed directly to the surface of said layer, rendering those portions of the layer, which are not covered by the design, insoluble by sensitizing and exposure to light, and removing the portions of the layer covered by the design and said design by dissolving these portions of the layer.

2. A process for preparing stencils for screen printing, said process comprising providing a stretched screen with a soluble stencil layer insensitive to light, applying a design to be printed directly to the surface of said layer by means of a painting or drawing material impermeable to light, rendering those portions of the layer which are not covered by the design insoluble by sensitizing said layer and exposing to light the surface carrying the design, and thereafter removing the portions of the layer covered by the design and said design by dissolving these portions of the layer.

3. A process for preparing stencils for screen printing, said process comprising providing a stretched screen with a soluble stencil layer insensitive to light, applying a design to be printed directly to the surface of said layer by means of a printing or drawing material which is impermeable to sensitizing solutions, rendering those portions of the layer which are not covered by the design sensitive to light by treating the surface of the layer carrying the design with a sensitizing solution and then rendering those portions of the layer which are not covered by the design insoluble by exposure to light, and removing the portions of the layer covered by the design and said design by dissolving these portions of the layer.

4. A process as claimed in claim 2, in which the stencil layer consists of a dried solution of glue and sensitizing is effected by means of a solution of ammonium bichromate.

5. A process as claimed in claim 3, in which the stencil layer consists of a dried solution of glue and sensitizing is effected by means of a solution of ammonium bichromate.

6. A product adapted to be used in the preparation of stencils for screen printing, said product comprising a screen and a stencil layer applied directly to said screen, said layer consisting of portions registering with the design to be printed, which are not light-sensitized, and residual portions which are light-sensitized.

GEORGES KANITZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 8,853 Zuccato Aug. 12, 1879 485,602 Bell Nov. 8, 1892 1,327,931 Waters Jan. 13, 1920 2,064,764 Playford Dec. 15, 1936

Claims

1. A PROCESS FOR PREPARING STENCILS FOR SCREEN PRINTING, SAID PROCESS COMPRISING PROVIDING A STRETCHED SCREEN WITH A SOLUBLE STENCIL LAYER INSENTITIVE TO LIGTH, APPLYING A DESIGN TO BE PRINTED DIRECTLY TO THE SURFACE OF SAID LAYER, RENDERING THOSE PORTIONS OF THE LAYER, WHICH ARE NOT COVERED BY THE DESIGN, INSOLUBLE BY SENSITIZING AND EXPOSURE TO LIGHT, AND REMOVING THE PORTIONS OF THE LAYER COVERED BY THE DESIGN AND SAID DESIGN BY DISSOLVING THESE PORTIONS OF THE LAYER.