A process for the production of an intaglio printing roller for the reproduction of monochrome or polychrome half-tone copies by photomechanical means for textile printing

摘要

602,885. Producing photo-mechanical printing rollers. HEBERLEIN & CO., AKT.-GES. July 11, 1945, No. 17694. Convention date, July 21, 1944. Addition to 567,126. Drawings to Specification. [Class 98 (ii)] The process of the parent Specification for producing an intaglio printing roller for the reproduction of monochrome or polychrome half-tone copies by photo-mechanical means for textile-printing is modified in that, by a suitable selection of stops and length of exposure, a screened positive, which is copied on to a light-sensitive etching resist layer on the roller, is produced exhibiting in the shadows white dots corresponding to the requisite supports for the doctor which are initially of sufficient size to avoid breaking out during use, the said positive being retouched in the lighter parts by local weakening to make the tonal values appear correct. The positive may be made either by contact printing from a screened negative obtained by photographing an original through a screen in contact with the film and a circular stop, or by photographing a continuous-tone negative through an out-ofcontact screen and a quadrilateral stop. Instead of correcting the screened positive, the requisite correction of the tone values may be effected by intensifying the screened negative from which the positive is contact printed. If desired, the screened positive may be treated so as to bleach the silver image and tan the gelatine in the parts containing silver.