US2139917A - Method for the production of color printing plates - Google Patents

Description

w. F. SINN 2,l3,917

METHOD FOR THE PRODUCTION OF COLOR PRINTING PLATES Dec. 13,. 1938.

5 Sheets-Sheet 1 Filed Sept. 2, 1956 INVENTOR. PZ ALTE/P i. J/v/v.

INVENTOR.

M 715? FLSINIV' ATTORNEY.

W. F. SINN METHOD FOR THE PRODUCTION OF COLOR PRINTING PLATES Flled Sept 2, 1936 W. F. SINN Dec. 13, 1938.

METHOD FOR THE PRODUCTION OF COLOR PRINTING PLATES Filed Sept. 2, 1936 3 Sheets-Sheet 3 INVENTOR. VIZ: 4.7-5? F/LjN/V. BY 4 J41 ATTORNE Patented Dec. 13, 1938 METHOD FOR THE PRODUCTION OF COLOR PRINTING PLATES Walter F. Sinn, Bidgcwood, Brooklyn, N. v.

Application September 2, 1936, Serial No. 99,073

6 Claims.

The present invention relates to a method of making color printing plates for the production of multi-color printed pictures and designs from a black and white original or from a black and white or neutra negative made from a colored picture, the method obviating the use of a color camera and the preparation of a negative for each color.

The present method of preparing color printing plates involves the use of a separate negative for each coloration separation. The process requires considerable time, great care and skill and is very expensive for commercial use not I only in the preparation of the negatives, but in finishing the color printing plates after the respective images have been produced thereon.

The characteristic of the present invention' is that a single key negative is employed for each color separation in conjunction with masks which 3 control thecolor shading and all desired modification of the original picture. The colors indicated for the specific picture may be brought out according'to nature or to the requirements of the finished picture with exactitude, whereas,

in the preparation of a separate negative for each of a plurality of colors, by the use of a color camera, certain colors by reason of their light refractive properties are not correctly reproduced, and there is a tendency for an overlapping of colors, so that in addition to the greater initial cost there is added the necessity for skilled and expensive work in correcting, changing and finishing the metal printing plates, with the final result uncertain; All of this is avoided by means of the present invention.

The invention will be described with reference to the accompanying drawings, in which:

Figure 1 is a plan view of a black and white picture designed for multicolor reproduction.

Figure 2 is a plan view of a key negative retouched to add highlights and brilliance to the several color positives later to be made therefrom.

Figure 3 is a plan view of the-first exposure mask.

Figure 4 is a plan view of a positive plate produced by first exposure of the key negative in conjunction with the first mask illustrated in Figure 3.

Figure 5 is a schematic view showing the position of the key negative, mask and the sensitized plate in the production of the first exposure image shown in Figure 4.

Figure 6 is a schematic view showing the sensitized plate bearing'the image of Figure 4 subjected to a second exposure through the second exposure mask shown in Figure 7.

Figure 7 is a plan view of the second exposure mask. Figure 8 is a view of the sensitized plate in its condition after the second exposure.

Figure 9 and Figure 10 are schematic views showing the use of the positive plate illustrated in Figure 8 for photogravure work, Figure 9 showing a first exposure upon carbon tissue through a screen, and Figure 10 showing a second exposure upon carbon tissue bearing a screen image of the image illustrated in Figure 8.

Figure 11 is a diagrammatic view in perspective, showing the reproduction of the image illustrated in Figure 8 upon a photomechanical plate through a screen by photography.

Figure 12 is a plan view of the first exposure mask for a second color.

Figure 13 is a plan view of an image produced photographically by exposure through the key negative of Figure 2, and the first exposure mask of Figure 12.

Figure 14 is a plan view of the second exposure mask, for said second color.

Figure 15 is a plan view of the image plate shown in Figure 13 after the second mask exposure.

Referring to the drawings, I have shown in Figure 1 a plan view of a black and white or neutral picture selected for reproduction in multi-color, and therefore through the production of a printing plate for each color. The first step in my process is to prepare the key negative of the desired size from the original picture shown in Figure 1. Of course, if the original picture is smaller than that desired for the printing plate, the key negative will be an enlargement and vice versa. The key negative then is retouched by emphasizing the highlights through the application of opaque or semi-opaque coating upon the negative at those parts desired to be brought out in brilliance, as shown in Figure 2. I then prepare a mask which will be opaque as to all of the areas not desired for the particular color. The mask is shown in Figure 3 and it will be noted that the original picture has been blocked out by an opaque material except for the two faces and the hand and that the face areas have been shaded, the shaded areas partially shutting out the light so as to either block out the particular matter at the shaded areas or reduce its intensity according to the use of either an opaque sheet or a partially opaque sheet.

*It will thus be seen that in the key negative all of the detail to be found in the original picture and in the multi-color reproduction thereof will appear. In the first exposure mask shown in Figure'3, the area of the original picture, not to be printed in the particular color for the mask as designed, will be made opaque as at Ix, Figure 3, with the exception that the opaque portion of the first exposure maskmayalso include areas of the sensitized plate which are light exposed through the use of the second exposure mask, as later to be explained.

In the first exposure mask certain of the shaded highlights of the mask are indicated at 2. After the preparation of the first exposure mask I, it is placed in contact with the key negative 3 at the emulsion facethereof and the two placed in contact with a sensitized plate 4. Thereupon an exposureis made, as by use of a light source 5.

After the employment of the first exposure mask and key negative as described, I place the second exposure mask 6 upon the partially exposed sensitized plate of Figure 4, as schematically shown in Figure 6, and thereby intensify those areas where deep color is desired, in the present example, the hair areas Gitf'th color decorative'band I and the shoulder decorative members 8, the final result being shown in Figure This production of color intensity at the areas stated cannot be satisfactorily produced in the first exposure through the key negative because of the density of the latter in exemplifying the complete design, but the second ,exposure of the sensitized plate satisfactorily brings out the desired eilect without modifying the highlight areas, these areas being protected by the opaque portion in: of the second exposure mask.

It will be understood that a very simple pic.- ture has been selected to illustrate the successive steps of my method and that the process is applicable to all types of picture and design reproductions whether they incorporate intricate detail or simple forms.

The completed positive produced by my method is shown in Figure 8, that part of the original picture to be printed in yellow, as an example, having been reproduced. The yellow will be intensified at the hair areas 6x and the costume elements I and 8.

In the production of. the mechanical printing plate, I have indicated in Figure 9 a sheet oi carbon tissue 9, a screen l0 anda light source H. The first step is to print the screen upon the carbon tissue by a first exposure and, as indicated in Figure 10, to print the image through the positive plate of Figure 8 upon the carbon tissue bearing the screen image. The finished positive, for the color yellow is indicated in Figure 10 at I2. The carbon tissue may then be employed in the usual photo-gravure processes for the production .of the final ink receiving printing plate.

For the production of a half-tone ink receiving printing plate, the positive l2 may be placed upon an easel I3 and light thrown upon it from the rear, as by the carbon arcs II, a rear light reflector l5 preferably being employed. Within a camera it will be placed the half-tone screen I! and back of the screen a sensitized plate l8. The positive l2 may by means ofthe camera be suitably enlarged or reduced. From the final plate l8 may be printed and etched the final ink receiving printing plate as will be understood without further explanation.

To further illustrate the invention, I have shown in Figures 12 to 15 inclusivathe preparaareas.

aisaeiv tion of a positive for a second color, selecting red as an example, inasmuch as for the subject illusshown in Figure 13 at 20-. In the mask l9 certain highlights, as, for example, the eyes, the teeth area of the woman figure, color and white exposed shirting of the male figure, etc. are made opaque or suitably shaded so as to entirely eliminate color or reduce color at such points. After exposure of the positive plate through the first exposure negative, for the color red, a second mask indicated in Figure 14 at 2| is employed. The purpose of the latter mask is to intensify the color red at certain areas without aflecting the general design and shading at remaining Thus the cheeks are intensified by the lightly shaded areas 2N1. At the area 22$ the color red is intensified-largely for the purpose of color blending with a subsequent color, blue, for example, the area being shaded however in the present example to aid in the draping effect of the woman's garment.

Referring back to Figures 12 and 13, it will be seen that in the background 19w light has been held backto a certain degree so that in the first exposure of the sensitized plate through mask ID the background will be substantially lighter than the figures and hence carry substantially less of the color red.

By reason of the use of the second mask 2|, in the final positive 22, the dress of the womans figure will be predominantly red, fresh tone with high color at the cheeks of the woman will be .produced by the combination of red and yellow at such areas, the highlights of the hairwill appear with the yellow or gold coloration of the costume elements 8 emphasized and each detail of the figures including their costumes brought out with exactitude as to color and detail.

Where a group of two or more pictures is laid out for a single print, as frequently in color advertising, I use but one negative for the entire group, whereas by present methods, three separate negatives are required for each picture of the group in order to secure the required colors. For example, a group of six pictures to be used in one advertisement, will require at least eighteen negatives. My process can accomplish the result with a single negative.

Myprocess does away with all the skilled and expensive work now requiredin correcting, changing. and finishing metal color' printing plates. This work of preparing the printing plates often requires weeks of time and is very expensive. In my process, all corrections are readily made on the original negative and by trolled by the original negative and the color is controlled by the masks in preparing the color separation positives. .My process also permits of simple, easy registration of color plates during the process, as the prints are made from original negative and color separation plates for registration and correction instead of metal printing plates as required in present processes.

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

1. In the production of color printingplates, the step of producing a transparent key negative of the desired image, the step of reproducing the image through said negative upon a sensitized photographic surface whilst blocking out areas of the image not to be reproduced in the given color, the step of subjecting the sensitized surface to a second exposure through a mask which passes light rays to those areas of the image on the sensitized surface desired to be shown in a relatively deep color density, developing the posi* tive thus produced and photographically reproducing the positive upon a photo-mechanical medium.

2. In the production of color printing plates, the step of producing a transparent key negative of the desired image, the step of reproducing the image through said negative upon a sensitized photographic surf-ace whilst blocking out areas of the image not to be reproduced in the given color, and the step of subjecting the sensi-.

tized surface to a second exposure through a mask having shaded areas at which the passage of light is reduced, having opaque areas through which a passage of light is barred, and having areas through which light is freely passed to those areas of the image on the sensitized plate desired to be shown in a relatively deep color density.

3- In the production of color printing plates, the step of producing a transparent key negative of the desired image, the step of reproducing that part of the image selected for a given color by a light exposure through said negative and through a mask blocking out areas of the'image not to be reproduced in the given color, upon a sensitized photographic surface, the step of subjecting the sensitized surface to a second exposure through a mask which passes light rays.

to those areas of the image on the sensitized surface desired to be shown in relatively deep color density, developing the positive thus produced, and photographically reproducing the positive upon a photo-mechanical plate.

In the production of color printing plates, the step of producing a transparent key negative of the desired image, the step of emphasizing the highlights of the negative image by increasing the opacity of the highlight areas, the step of reproducing that part of the image selected for a given color by light exposure through said negative upon a sensitized photographic surface whilst blocking out areas of the image not to be reproduced in the given color, the step of subjecting the sensitized surface to a second exposure through a mask which passes light-rays to those areas of the image on the sensitized plate desired to be shown in relatively deep color den-.-' sity, developing the positive thus produced, and photographically reproducing the position upon a photo-mechanical plate.

In the production of first and second color printing plates, the step of producing a transparent key negative of the desired image, the step of reproducing that part of the image selected for the first color by light'exposure upon a sensitized surface through said negative and a mask which blocks out areas of the image not to be reproduced in said color, as a step in the process subjecting the sensitized surface to an exposure through a second mask which passes light rays to those image areas desired to be shown in relatively deep color density, the step of light exposing a second sensitized surface through said negative whilst blocking out areas of the image not to be reproduced in the second color, subjecting the second sensitized surface to an exposure through a mask whichpasses light rays to those image areas desired'to be shown in relatively deep color density, developing the positives thus produced and photographically reproducing each positive upon a photo-mechanical medium.

6. In the production of first and second color printing plates, the step of producing a transparent key negative of the desired image, the step of coloring said negative to add highlights and brilliance, the step of reproducing that part of the image selected for the first color by light exposure upon a sensitized surface through said negative and a mask which blocks out areas of the image not to be reproduced in said color, as a step in the process subjecting the sensitized surface to an exposure through a second mask which passes light rays to those image areas desired to be shown in relatively deep color density, the step of light exposing a second sensitized surface through said negative whilst blocking out areas of the image not to be reproduced in the second color, subjecting the second sensitized surface to an exposure through a mask which passes ical medium.

WALTER F. SINN.

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