US2320914A - Process of color separation in lithography - Google Patents

Description

June 1, 1943. J. CUNNINGHAM 2,320,914

PROCESS OF COLOR SEPARATION IN LITHOGRAPHY Filed Jan. 29 1942 LITHDERAPHY INVEN TOR. 22/115 @N/W/Vfi/MM Patenteii June 1, 1943 UNITED STATS PROCESS OF COLOR SEPARATHON IN LITHOGRAPHY James Cunningham, New York, N. Y., assignor of twenty per cent to Michael Dichiaro, Brooklyn,

Application January 29, 1942, Serial No. 4282699 4 Claims.

This invention relates to ration in lithography.

In the present method employed in the separation of color in the lithograph industry, each color must be opaqued out. In the reproduction process of color sepaof a two color job, for example, red and blue, the

original copy is set on the copy board in the camera department and a negative is then made from the same. The negative is then stripped or placed in position on glass or Celluloid, or any other material suitable for reproduction of the negative.

The negative then goes to the opaquing department where the color separation takes place. To prepare or opaque said negative for red plate, the part of the negative which is to be reproduced in blue is first opaqued out. The negative then goes to the sensitized emulsion plate department, and a contact sensitized emulsion plate is made from the same. This plate only reproduces the part which has not been opaqued out and is hence, the red plate.

The negative is then returned to the opaquing department. The part which was previously opaqued out (the part to be reproduced in blue), is then washed clear of the opaque previously applied. The part which is to be reproduced in red is then opaqued out, and the negative again gOes back to the sensitized emulsion department,

and a contact sensitized emulsion plate is made from the same to reproduce the part which is to be reproduced in blue. Thus, each part to be reproduced must be successively opaqued out.

It is therefore an object of the present invention to partially eliminate the opaquing process,

so that in a red, blue job, for example, only the part to be reproduced in one color is to be opaqued out and not the other.

A further object of this invention is to provide a highly economical and efficient process of the character described, which shall be easy to carry out, and practical to a high degree in use.

Other objects of this invention will in part be obvious and in part hereinafter pointed out.

The invention accordingly consists in the combination of steps, features of construction, combinations of elements, and arrangement of parts which will be exemplified in the process and construction hereinafter described, and of which the scope of application will be indicated in the following claims.

In the accompanying drawing, in which is shown one of the various possible illustrative embodiments of this invention,

Fig. 1 is a top plan view of a collodion negative;

Fig. 2 is a top plan view of the negative, with dye applied to the surface of the negative to be reproduced in red; and

Fig. 3 is atop plan view of the article shown in Fig. 2, with a yellow glass plate on top of it.

Fig. 4 is a cross section on the line 44 of Fig. 3.

In accordance with the present invention, one of the opaquing steps is eliminated. The process necessitates the use of a photo-engravers wet plate or collodion coated negative. The collodion negative is necessarily a part of this process as it forms a base to which a saturated solution consisting of fuchsine crystals in methyl alcohol, a dye applied in the process, adhere.

The process of reproducing of a two color job, red and blue, in accordance with the present invention, will now be described, as an example of the process.

The original copy is set on the copy board in the camera department and a negative is then made from the same. The negative is preferably collodion covered. The negative is then stripped or placed in position on glass or Celluloid, or any other substance suitable for the reproduction of the same.

The negative then goes to the opaquing department where the color separation takes place. To prepare or opaque said negative for red plate, opaque out the part of the negative which is to be reproduced in blue. The negative then goes to the sensitized emulsion plate department, and a contact sensitized emulsion plate is made from said negative. This plate only reproduces a part of the negative which was left clear and which is to be reproduced in red.

Up to this point, the process is substantially the same as the process used heretofore in two color lithography. However, with the present invention, the negative is then returned to the opaquing department, where a saturated solution comprising fuchsine crystals in methyl alcohol is applied to the part of the negative which is to be reproduced in red. After this dye or solution has been applied to the negative, the previously opaqued part is washed oil, leaving the part to be reproduced in blue clear.

In accordance with the present invention, furthermore, a yellow glass is placed over the negative in the printing frame. Instead of using a yellow glass, the same results may be achieved by stripping the negative on a yellow glass or Celluloid instead of on clear glass or Celluloid, or by covering the clear transparent glass on which the negative is stripped with yellow Cellophane or Celluloid, or by any other yellow substance through which light can penetrate.

I have found that the combination of the red dye, comprising (saturated solution of fuchsine crystals and methyl alcohol) and the yellow glass or yellow Celluloid or Cellophane, prevent formation of an image on the emulsion plate in the normal time exposure allowed for the reproduction. Thus, the use of the dye and the alcohol glass or Celluloid or Cellophane takes the place of the second opaquing process heretofore used.

After the dye is applied to the part to be reproduced in red, the negative is again returned to the sensitized emulsion department, and a i contact sensitized emulsion plate is made from the same. As stated above, this plate will only reproduce the part to be reproduced in blue and not the part to which the dye has been applied.

In the drawing, l designates a collodion covered negative.

'In Fig. 2, the negative is shown with the dye ll applied to the part to be reproduced in red, leaving clear the part l2 to be reproduced in blue.

In Fig. 3 there is shown a plate IA of glass applied over the negative.

It will thus be seen that there is provided a device and process in which the several objects .of this invention are achieved, and which is well adapted to meet the conditions of practical use.

As various possible embodiments might be made of the above invention, and as various changes might be made in the embodiment above set forth, it is to be understood that all matter herein set forth or shown in the accompanying drawing is to be interpreted as illustrative and not in a limiting sense.

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

1. A process of the character described, consisting in opaquing out a part of a negative to be reproduced in one color, then applying a contact sensitized emulsion plate to the negative to make a print therefrom of the part of the negative which has not been opaqued; then applying to the part of the negative which has not been opaqued, a dye consisting of fuchsine crystals dissolved in methyl alcohol, and washing out the opaquing on the part which has been previously opaqued, placing a yellow plate over the negative, and then making a contact sensitized emulsion plate from the negative to reproduce on the second contact sensitized emulsion plate, the part of the negative which was originally opaqued, and from which part the opaquing was washed away.

2. A process of the character described, consisting in making a negative, then opaquing out part of the negative, then printing a plate from the negative to reproduce the part which has not been opaqued out, then applying a solution of fuchsine crystals to the part of the negative which was not opaqued out, and then removing from the negative the opaque previously applied to the part which has been opaqued out.

3. A process of the character described, consisting in making a negative, then opaquing out part of the negative, then printing a plate from the negative to reproduce the part which has not been opaqued out, then applying a solution of fuchsine crystals to the part of the negative which was not opaqued out, then removing from the negative the opaque previously applied to the part which has been opaqued out, and superimposing a yellow light transmitting memher over the negative.

4. A process of the character described, consisting in making a negative, then opaquing out part of the negative, then printing a plate from the negative to reproduce the part which has not been opaqued out, then applying a solution of fuchsine crystals to the part of the negative which was not opaqued out, then removing from the negative the opaque previously applied to the part which has been opaqued out, and superimposing a yellow light transmitting member over the negative, and then making a print from the negative to reproduce the part to which the solution was not applied.

JAMES CUNNINGHAM.

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