Patent GB-417640-A (GB)
Title: Improvements in kinematograph films and in methods for the production thereof
IPC: G03C7/26
Filed: 1933-04-05
Abstract: 417,640. Colour photography and kinematography. THORNTON, J. E., 8, Hill Street, Jersey, Channel Islands. April 5, 1933, No. 10154/34. Divided out of 417,722. [Class 98 (ii).] In a process, such as that described in Specification 17007/05, [Class 98], of producing a relief image in a coloured colloid layer by chemical contact action when the layer is placed in contact with a layer carrying a developed silver image, the two layers are placed together in intimate contact before treatment with the oxidizing bath which effects the chemical contact action. The colloid relief image is developed in situ upon the silver image layer, and the silver, which has been bleached by the oxidizing bath, is removed as by hypo or Farmer's reducer. The process is applicable to the production of monochrome or multicolour photographs on opaque or transparent supports, or kinematograph films. The colloid layer preferably comprises a mixture of gelatin and glue, but other colloids such as gelatin, glue, fish-glue, albumen, casein, gumarabic, gum-tragacanth, agar-agar, or dextrin, singly or in admixture, may be used ; and it is coloured as by pigments, insoluble dyes or lakes, vat dyes in colloidal dispersion, or leuco dye-compounds. The layer may be used as a colloid film cast without any backing ; or it may be cast on a temporary support of porous paper or viscose. Adhesion to the silver image layer is ensured as by wetting either the colloid layer, or the image layer, or both, before bringing them together, as with plain water, or with a softening agent such as an aqueous solution of an alkali, alkaline salt, or glacial acetic acid, or with a dilute solution of glue or by incorporating glue in one or both layers or by roughening one or both layers either mechanically as by pressure against an engraved roller, or chemically by an etching liquid such as an aqueous solution of calcium or potassium ferricyanide, zinc chloride, calcium nitrate, ferric chloride, or sodium chloride. Intimate contact is further ensured by application of pressure, as by squeegee or by pressure rolls which may be submerged in water. The adhering layers are preferably dried before immersion in the oxidizing liquid, which passes through the porous paper support (if used) of the coloured colloid layer to the silver image layer, and differentially hardens the colloid of the coloured colloid layer at each point in direct proportion to the amount of silver in the adhering image layer. The unhardened colloid in the coloured layer is then removed as with hot or cold water according to the nature of the colloid, which simultaneously removes the temporary porous paper support (if used), and leaves a coloured colloid relief image superimposed on the bleached silver image layer. Hypo or Farmer's reducer is then applied to remove the bleached silver from the image layer, and the print is finally washed and dried. The washing step may be shortened by removing the bleached silver before developing the relief with hot or cold water. When the relief is developed with hot water, preliminary hardening of the silver image layer is necessary, sufficiently to make it resistant to the action of the hot water ; this may be effected as by adding chrome alum to the emulsion during manufacture, or after development by a hardening bath of chrome alum or formalin or a combined hardening and fixing bath. The Specification refers to various known modifications of the process described in Specification 17007/05, and refers also to Specification 17773/89, [Class 98]. It also mentions various known oxidizing baths, containing potassium bromide and (1) copper sulphate, potassium bichromate and hydrochloric acid, or (2) potassium bichromate or chromic acid, and potassium ferricyanide, or (3) copper chloride and potassium bichromate. The Provisional Specification refers also to the production of kinematograph picture films bearing sound records ; and describes the production of a two-colour picture film by printing component silver images in emulsion layers on opposite sides of a single support as described in Specification 373,312, and colouring them in the above-stated manner with complementary colours.