GB511800A - Filter-layers for colour photography - Google Patents

Abstract

511,800. Filter layers for colour photography. KODAK, Ltd., and CROWTHER, R. E. Feb. 25, 1938, No. 6063. [Class 98 (ii)] Photographic material more particularly for colour photography includes a filter layer or layers comprising a coloured dispersion of silver sulphide, silver selenide, or silver telluride. Multi layer material comprises a support, a red sensitive layer, a gelatine intermediate layer or a yellow -filter layer, a green sensitive layer, a yellow filter layer and a not specially sensitized blue sensitive layer. The position of the red and green sensitive layers may be interchanged. The emulsion layers may be on one or both sides of the support, and any or all may contain colour formers. The material may comprise a mixed emulsion layer. The filter layers may be applied to lenticular or multicular screen type colour photographic material. A yellow silver sulphide filter layer is prepared by coating a solution of silver nitrate and gelatine in water on to a support, and immersing the coated support in ammoniacal thiourea solution until the desired depth of yellow is reached. The coloured gelatine is washed and stripped from the support, and may be re-melted and treated with a hardening agent. The'production of the filter material may be effected in a vessel instead of on. a support. The filter layer is decolorized by a solution of potassium ferricyanide and sodium thiosulphate, but is not affected by a silver rehalogenizing bath such as a solution containing potassium ferricyanide, ammonia, and potassium bromide. Red, dispersions of silver sulphide, selenide, or telluride may also be made. Specifications 441,325, 500,611, 500,793 and 503,752 are referred The Provisional Specification describes also the use of colloidal sulphur, selenium and tellurium in filter layers.