GB522696A - Multilayer printing material for colour photography - Google Patents

Abstract

522,696. Colour photography. GASPER, B. Dec. 13, 1938, No. 36293. Convention date, Dec. 18, 1937. [Class 98 (ii)] Colour photographic multilayer printing material containing on a common transparent support three superposed light-sensitive layers of which the inner is exposed through one superimposed layer and the other from the opposite side of the support is characterized in that the inner layer contains the image-forming dye and is sensitized to light transmitted by this dye, and the outer layers do not contain image-forming dyes and are substantially identically sensitized for light against which the inner layer is screened by the contained dye. All the layers may be insensitive to a definite part of the visible light. At least one layer may be selectively sensitive to infra-red. The material may comprise a transparent carrier having on one side an uncoloured blue-sensitive silver halide emulsion layer and a lower silver halide emulsion layer green-sensitized with erythrosine and containing Milling Yellow G and an upper uncoloured blue-sensitized silver halide emulsion on the other. The yellow dye may be destroyed either at the silver or non-silver parts of the image. The uncoloured layers may be processed by (a) diffuse colouring and dye-destruction either at the silver or non-silver areas, (b) chemical toning, (c) dye-toning, (d) colour development, or (e) tanning and coloration of the untanned areas. A two-colour positive image may be printed on the double-coated side of the film and a negative image on the single coated side. White light or a mixture of green and blue light or successive exposures to green and blue light may be used for printing the two-colour positive image. Aqueous thiocarbamide solution may be used for printing. The image on the singlecoated side may be iron-toned blue by flotation, initial treatment with ammoniacal potassium ferricyanide being followed by treatment in a bath containing ferric ammonium sulphate and potassium bromide and slightly acidified with hydrochloric acid. The film is treated with a bleach-hardening bath containing ferricyanide, bromide, bichromate, and alum. After washing and drying one surface of the film is coloured with Polar Brilliant Red. The sound record may be printed on to the single-coated side of the film. In a modification the magenta colour is produced on the single-coated side by colour development, the surface of the double - layer side is coloured with Pontanine Sky Blue 5BX, and both the yellow and blue dyes locally destroyed with aqueous hydrobromic acid. The middle layer may be coloured magenta and sensitized to infra-red and the two outer layers sensitized to green, or the middle layer may be coloured blue-green and sensitized to infra-red and the two outer layers sensitized to red. A Mue-green or magenta layer may contain a yellow filter dyestuff. Specifications 397,159 and 421,534 are referred to.