GB559394A - Improvements in and relating to photographic processes - Google Patents

Abstract

559,394. Coloured photographic images. BOWEN, E. WINDSOR-, and GOWER, C. H. R. Aug. 15, 1942, No. 11460. [Class 98 (ii)] In a process wherein a dye or pigment image is produced on a support of aluminium or aluminium alloy having an anodised surface by photographically forming thereon resist areas and colouring the unprotected areas, the anodised surface is coated, before applying the lightsensitive colloid layer which is used in forming the resist, with an organic colloid inert to light which protects the anodised surface from the light-sensitizing agents in the superimposed layer. The colloid used for the layers may be gelatin, albumen, or gum arabic, and the coating solution is generally made weaker in colloid for the non-sensitive layer than for the light-sensitive layer. Bubbles in the non-sensitive layer are avoided by applying it in two stages, the second being wiped over the first after a short-interval to remove any bubbles which have formed therein. The light sensitive layer may be sensitized with bichromate, e.g. by adding ammonium bichromate and ammonia to an aqueous gelatin coating solution, or with ferric chloride; and the areas of the anodised surface laid bare during development of the layer are coloured, as with dyes. The anodised surface may then be sealed by treatment with a nickel salt followed by treatment in water at about boiling point, the hot water treatment serving also to remove the resist coating. If the anodised surface is dyed before applying the colloid coatings, a result in different colours is produced when the non-resist areas are subsequently dyed.