Photographic screen stencil printing process

Claim 1

A screen stencil printing process comprising: (a) providing a screening material, (b) coating the surface of the screening material conforming to the following specification S≧Δ.sub.o /(1-Δ.sub.o) wherein S is the fractional increase in linear dimension (thickness) of the screen fibers due to photoselective swelling, Δ o is the initial fractional open area of the screen as manufactured and coated, with a photosensitive material such that open areas are provided for expansion of said material into said open areas, said open areas of said screen being located between the coated screen fibers, said photosensitive material being capable of swelling upon exposure to actinic radiation and heat and being selected from the group consisting of photochromic compound-resin mixtures, diazo compound-resin mixtures, resin mixtures with a compound selected from the group consisting of p-azido-benzophenone, 4,4'-diazodobenzophenone, p-quinone diazides and a compound satisfying the formula ##STR2## wherein R 1 =R 2 =ethyl R 3 =Br and mixtures thereof, the ratio of said compound material to said resin material ranging from 4:1 by weight to about 1:20 by weight; (c) exposing said screening material to a pattern of actinic radiation; (d) heating said screening causing the photosensitive material to expand, thereby closing the open areas of the screen in the illuminated areas; (e) allowing said screening to cool; (f) contacting said screening with the surface to be marked; (g) forcing a marking material through the open areas of said screening; (h) lifting said screening from the marked surface; and (i) allowing said surface to dry.