| 摘要 |
442,887. Producing photomechanical printing surfaces. 1. G. FARBENINDUSTRIE AKT.-GES., Frankfort-on-Main, Germany. Aug. 17, 1934, No. 23774. Convention date, Aug. 19, 1933. [Class 98 (ii)] In a process for producing direct positives for autotype purposes from a line or half-tone copy, a film comprising a light-sensitive gelatin layer carried on a transparent support is exposed through the support under the copy, developed with a tanning developer, well washed with warm water to leave the gelatine relief, dried and dyed with a solution of a dyestuff which dyes the parts of the support laid bare by the production of the gelatin relief in a manner that it is impermeable to the photographically active rays, for example a solution of typophor black in a mixture of benzene and methanol, and the gelatin relief is removed from the support by hydrogenperoxide, dilute caustic soda solution, a solution of a thiocyanate, hypochlorite solution, papayotin or the like, the latter four reagents being applied at about 40‹ C.
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