US2469671A - Method of stenciling with sectional screens - Google Patents

Description

May 10, 1949.

w. 'r. WARDE METHOD OF STENCILING WITH SECTIONAL SCREENS 3 Sheets-Sheet 1 Filed July 30, 1945 INVENTOR. WALTER 7T WHIP/2E BY @476 m r flux-1.

May 10, 1949. w. T. WARDE 2,469,671

METHOD OF STENCILING WITH SECTIONAL SCREENS Filed July 30, 1945 3 Sheets-Sheet 2 INVEN TOR. N/PL TEE 7'2 WARDE W.mrw&

May 10, 1949. w. T. WARDE METHOD OF STENCILING WITH SECTIONAL SCREENS 3 Sheets-Sheet 3 Filed July 50, 1945 INVEN TOR.

WALTER 7T Wmwe.

BY 15%, M v

Patented May 10, 1949 METHOD OF STENCILlN scan GSWITH SECTIONAL Walter T. Warde, San Francisco, Calif., assignor to Foster and Kleiser Company, San Francisco, Calif., a corporation of Nevada Application July 30, 1945, Serial No. 607,702 3 Claims. 101-129) This invention relates to what is generally known as the silk screen process or silk screen stencil printing in which a stencil is carried by a screen or ground of silk, organdy, metal cloth or some other fabric. The usual practice involves forcing a printing medium, such as paint, through the mesh openings in the screen and onto the material to be printed with the design of the stencil.

Heretofore one of the principal objections to the use of the silk screen process has been the lack of an economical and simple method of reproducing subjects containing subtle shading such as is possible in lithography and the printing from half-toneplates. Photo-stencils perhaps are the closest approach heretofore made to the desired result but the photo-stencil method is complicated, costly and uncertain. Furthermore there is no way of satisfactorily doctoring up any defects'that may appear and which defects are not discoverable until the complicated and costly process of preparing the stencil is completed. Other objections to this method are iamiliar to those skilled in the art.

One of the principal objects of this invention is an economical and simple method of making a stencil screenthat will readily reproduce the desired subtle shading heretofore lacking in posters printed by the silk screen process upon squeegeeing the paint through the stencil screen.

Another object of the invention is a stencil screen that is adapted to produce subtle shading upon forcing the paint therethrough and onto the material to be printed.

Another object is a method of silk screen printing in which subtle shading, as desired, is pro duced in the printed image.

A still further object of the invention is a method of producing a plurality sheet poster by the silk screen processin which subtle shading of an image on the poster is adapted to extend over any number of separately printed sheets without apparent undesirable and improper dif-- ferences along the matching edges of the parts of the image printed on adjacent pairs of such sheets. I 1

Other objects and ,advantages appear in the description and drawings.

In the drawings Fig. 1 diagrammaticallyillustiates a plurality of silk screens in side by side 2 relationship and on which an image is traced preparatory for further steps in the process described.

Fig. 2 diagrammatically illustrates one 01' the screens 01' Fig. 1 between an overlying relatively coarse screen and a sheet or material to be printed and represents one of the last steps in the process to be described.

Fig. 3 represents a greatly enlarged view 011 silk stencil screen produced by the instant process.

F1Fig. 4 represents a printing from the screen of Fig. 5 is representative of the general eilect produced by a printing of the image of Fig. 1 after the steps of the present process practiced.

In detail the present method will be described with respect to the making of a single stencil screen for a single sheet as distinguished from the additional steps that may be required for the production of a poster from several sheets.

In making a stencil for a single sheet poster or for any product where the complete image or printed matter is to be on a single sheet, the desired image may be first outlined on the silk screen of the regular stenciling screen frame itself. Then any suitableblocking out material such as water paint, water soluble glue, shellac, lacquer, varnish, etc. is sprayed onto the screen, the character of said blocking out material being determined by the character of the paint used for printing. The blocking out material used must not be soluble by the ingredients of the paint used for printing.

The present method requires the step of controlling the deposit of the blocking out material so as to produce a pattern of unobstructed mesh openings and of blocked out mesh openings of a character that is such that the color or paint squeegeed through the unobstructed mesh openings will be of the desired weight in any areawithin the confines of the outline of the desired image to produce the desired density of tone or shade.

The production of the desired pattern is preferably accomplished by use of a large air brush regulated to produce a coarse splatter spray. Thus the silk can be entirely blocked out where no printing is to be done by use of the particular have been 3 screen being processed or any desired area of the screen may be left open or clear of the blocking out material. Between these two extively fine mesh of 124 tremes the splatter spray will uniformly vary the ratio of blocked out mesh openings to unobstructed mesh openings to whatever degree is desired. Referring to Fig. 3 it will be seen that the portion indicated in solid black represents the blocking out material. The apertures or openings i in the screen ar defined by the blocking out material and their outlines are highly irregular.

Assuming the section of the prepared screen of Fig. 3 were used for making a print, the result would be substantially as seen in Fig. 4 in which the black portions 2 indicate the deposits of color on the material to be printed while the white areas 3 represent the portions covered by the blocking out material on the screen.

These views, Figs. 3. 4, are considerably enlarged. As seen in a printed image the portion shown in Fig. 4 resembles stippling generally represented by the image of Fig. 5. The individual dots or spots making up the shaded portions substantially lose their individual identity when viewed from a distance, as on' billboards, but their peculiar character gives general results that are vigorous, brilliant, pleasing and substantially free from the more or less mechanical eifects produced by the conventional complicated and expensive photo-stencils or shading sheets.

Most posters are printed in several colors. Sometimes as high as forty colors are used and in silk stencil printing a separate screen is used for each color. The present method enables the blending of different colors in any desired ratio. i

This does not mean wet blending but the printing of one color over the other or a combination of such printing with a juxtaposition of colors. Thus soft or brilliant effects can be produced that are impossible with printing by conventional methods.

Where the silk screen process is used for printing a 24 sheet size poster only nine sheets are required. The matching of the prints on the respective sheets to make the full poster offers no difficulty where no attempt is made to graduate the colors in any one or more imprints but where, as here, the preparation of each screen for each of the nine sheets requires a controlled spraying to produce subtle shading, the conventional methods will not sufiice.

Fig. 1 illustrates a series of screens Ill, ll, l2, l3,

count while the silk on the stencil frame may be about '15 count so asto enable free passage oi paint to the stencil screen. The regular stencil frame is. of course. considerably larger than the printed portion of the sheet and of the prepared silk screen stencil. But in those instances where the problem of matching line and weight of color on separately printed sheets is not present the regular screen in the stencil frame may be prepared as hereinbefore explained.

the dimensions of each being less than the dimensions-of the screen that is in the printing frame and the distance between the elongated edges of each portion of the image to be printed.

With screens Ill to l3 arranged coplanar in edge to edge relation the image I may be traced thereon preparatory to spraying with the blocking out material the same as were these screens a single screen. The blocking out material is then sprayed onto the screens exactly as described for the single screen, the image extending over portions of all the screens.

Each screen may then be positioned between the sheet I 5 to be imprinted and the substantially larger mesh screen l6 of the regular printing frame. The color or paint is then squeegeed through the two screens onto sheet I5. The resultant printings on sheets 20, 2|, 22, 23 (Fig. 5)

will match perfectly both in the direction of line The foregoing examples of screen mesh that may be used are not to be considered restrictive. The stencil screen may be coarser or finer as desired. Usually, however. a coarser spray is used for the coarser screens and a finer spray for finer screens. Also the consistency of the paint used has some effect on the results. A thin paint tends to produce a coarser stippie effect while a paint that is thicker produces finer stipples. However, in any event, there is no mechanical regularity in the outlines of the individual dots that are produced, but there is a definitely controlled ratio between the obstructed and unobstructed areas in various portionsof the screen to produce the desired weight of color or density of the shading, tone or tint.

What actually occurs by the present method is that the image to be printed is defined in the stencil screen by the blocking out medium in distributed deposits in which the ratio between the deposits and the unobstructed mesh openings between them in the various portions of the image is in reverse proportion to the density of the shade to be printed by use of the screen. Thus where a portion of the image to be printed is of a light shade or tone, the deposit of blocking out medium covers a substantially greater amount of the area in proportion than is left unobstructed and for progressively darker shades the ratio between the area covered by the blocking out medium and that area left unobstructed becomes less and may continue to the point where.

there is an absence of blocking out medium and the consequent printing of a solid color.

Inasmuch as the silk screen process of printing frequently is used to deposit a light color on a darker one or on a dark paper or material, it is obvious that white may be deposited on black or on any other color where my invention is used to give a tone that is between black and. white, although the deposits will be white and not grey nor will the black spaces between the white deposits be necessarily grey but they will remain black. Or black may be printed on white. Therefore, the use of the word color herein and in the claims is intended to include black and white, and the word "shade or "shading is intended to refer to a deposit of any colored paint, whether light or dark, that is less than an unbroken deposit of the particular color. The word "tone is synonymous with shade or shading whereever used herein. The shade or tone may be of light or heavy density or of graduated density or of any density between light and heavy. A heavy density printing would be one where the blocking out material was applied fairly lightly to the screen thus allowing a considerable amount of paint to pass through the screen but not enough to produce a solid color while a light density shade would be one where the blocking out material was applied a suflicient length of time and in an amount sufi'icient to restrict the passage of the paint through the screen to restricted mesh openings so that the deposits would be appreciably shade is desired and wherever it is desired on the screen.

In the same manner in describing the screen the term "density as applied to the blocking out medium refers to the distribution of the medium on the screen relative to the unobstructed area. The term does not refer to the specific gravity of the medium. .A heavy density of the medium means that the area covered by the deposits of the medium is relatively large as compared with the area between the deposits and a light density is the reverse. Any density between a solid blocked out portion and a completely unobstructed portion is obtainable.

The term silk Screen is intended to include screens of organdy or of metal cloth as well as screens of silk.

I claim:

1. A method of printing a multiple sheet poster by the silk screen process in which the image to be printed is of a size extending over a plurality of the sheets of such poster that comprises the steps of arranging a plurality of screens respectively of a size to correspond with the portion of the image to be printed in edge to edge, coplanar reiationship, spraying particles of a blocking out medium onto said screens and across their adjoining edges in a pattern and density for defining the outline of parts of the image to be printed and the shade characteristics of the said parts, then making separate prints on sheets of paper from each of said screens by said process for final assembly and matching of such sheets to produce theposter.

2. The method of printing a multiple sheet poster by the silk screen process in which the image to be printed is of a size extending over a plurality of the sheets or such poster that comprises the steps of arranging a plurality of screens respectively of a size corresponding exaetly in width with the portion of the image to be printed in edge to edge coplanar relationship, spraying particles of a blocking out medium onto said screens and across their adjoining edges in a pattern and density for defining the outline of the parts of the image to be printed and the shade characteristics of said parts, then separately positioning each such screen between the open areaof an open screen of larger size and coarser mesh and the sheet to receive the paint, and squeegeeing the paint in succession through said screens and onto said sheet, thereby producing separate prints of said portions of the image that will match along edges thereof in the length of such edges and in the density of color when such separately printed sheets are arranged in the same relationship as the screens at the time the latter were in said edge to edge relationship.

3. The method of printing a multiple sheet poster by the silk screen process in which an image to be printed is variablyshaded by stippling and is of a size adopted to extend across the adjoining edges of a pair of said sheets that includes the steps of: arranging a pair of screens to be used for printing said image in edge to edge coplanar relationship, spraying particles 01 a blocking out medium onto said screens and across their adjoining edges in a pattern and density for defining the outline and shade characteristics of said image, then separately positioning such screens in succession between the open area of a taut open screen of larger size and of coarser mesh and the sheet receive the paint, squeegeeing the paint in succession through said screens and into said sheet thereby producing separate prints of the portion of the image formed on each screen that will match along their adjoining edges in density of the stippling when such printed sheets are arranged in the same relationship as the screens at the time they were in said edge to edge relationship.

WALTER T. WARDE.

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

UNITED STATES PATENTS Great Britain Sept. 6, 1928 I

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