SU34316A1 - A method of making artificial raster negatives or transparencies for three-color offset printing - Google Patents

Description

The proposed method of making artificial raster Negatives or transparencies for three-color offset printing is as follows. The finished and retouched autotypical cliche is etched with the Strecker salt (to impart the ability to absorb moisture to the metal) or degreased with some caustic alkali. Following this, cliches are poured with sedative mixture:

Vodozoozh

Dextrin common 50 g

Sahara. . . 20g

Soap alcohol - a few drops. The plate coated with this composition is dried either in a centrofuge or in the usual order. Thus, the cliché is covered with an impermeable layer that lies tightly and evenly on both the raster points and in the spaces between them.

The following manipulation is the application of paint on the plate and the removal of excess. A piece of celluloid or horny plate cliché rub over translate lithographic paint, somewhat diluted with French turpentine. After that, they roll a typographical (mass) wave, which removes the excess cr &sk; Roller removes the paint from the upper parts of the cliché, leaving it in between (138)

do autotype points. In operation, the roller is cleaned with kerosene, wiped with rubbing and re-rolled in cliches. This operation is performed until all the raster points are free of paint, and the latter will remain only in the recesses between them and give a negative mesh image.

Prepared in this way, the dash is poured with collodion of the following composition:

5% collodion ..... .400 ate

Alcohol (methyl) .... 150 cjf

Castor oil11 ate

The high content of alcohol in the collodion makes it possible to obtain an even dense film, and the presence of castor oil does not allow it to deform during subsequent manipulations of its transfer and mating.

After the collodion has dried, the cliché is dipped into hot water, the latter dissolves the dextrin sublayer and separates the film from the plate, the film tightly trapping the ink between the raster points. This film (negative) can be strengthened (glued with gums mixed with soap alcohol) on any surface - on glass, on transparent celluloid, etc.

The artificial negative thus obtained is copied in a conventional manner onto a flat plate.

The production of a slide occurs in the same order, with the only difference that the cliché is not rubbed with paint, but it is rolled by a usual method, and the Further process is similar to that described above.

The author indicates; That the proposed method is capable of producing (strengthening or weakening) on a cliche separate parts of the image.

In some cases, the method described may be simplified. For example, the operation of applying a dextrin sublayer may be eliminated, however, in this case, to separate the collodion film, it is necessary to withstand the plate for at least five minutes in a strong acetic acid, after which the film with the image can be easily separated from the lip. This technique, however, can only be used for monochrome (for example, black) works, since it is not possible to guarantee a match of colors, due to possible stretching of the film (softened by the action of acetic acid on collodion).

LVR believes that the described method can be applied not only for

offset, but also for mezzotinto intaglio printing, since the need for extremely difficult and painstaking retouching used for this printing is eliminated due to the possibility of obtaining a developed artificial slide film.

The subject invention) and.

A method of making artificial halftone negatives or transparencies for three-color offset printing, characterized in that the finished and retouched avtotipnoe etched cliché srlyu Strecker or caustic alkali and pour soluble in hot water, grease-proof sublayer, after which all the transfer pad za5irayut lithographic ink and reduces mayutsya gelatin roller all the paint from the surface of the cliché, leaving it only in the intervals between the raster points, then the surface of the cliche is poured with a layer of collodion mixed with storovogo oil and alcohol, let it harden and lower pad in hot water to separate the film from the pad, after which the resulting artificial film attached to a transparent support.