GB340278A - Improvements in or relating to processes for the manufacture of light sensitive layers for colour photography - Google Patents

Abstract

340,278. Plates and films for colour photography. HEIDE, E. WOLFF-, 16, Kopenhagenstrasse, Berlin. Sept. 17, 1929, No. 28206. [Class 98 (ii).] Light-sensitive negative material for subtractive work comprises a single light-sensitive layer which is treated so as to divide it into three colour-sensitive regions from the bottom surface to the top. An ordinary emulsion layer is treated with a colloidal solution of pinaflavol or other green sensitizer for a time sufficient to allow the dye to penetrate to the intermediate portion of the layer. After drying, the layer is treated with a colloidal solution of pinacyanol or other red sensitizer, for a time sufficient to allow the dye to penetrate into the surface portion only. After drying again, the whole layer is treated with an orange dye which will absorb blue and green rays but will transmit red rays. The colloidal sensitizing solutions penetrate into the emulsion layer with difficulty, and the duration of application to achieve the necessary depth of penetration is determined experimentally as by exposing trial plates. The intensity of the orange staining may be graded, so that it decreases from the top of the layer to the bottom, as by using an aqueous solution of a mixture of rapid filter yellow and rose Bengal, which penetrates into gelatine very slowly. On exposing the layer through its support to a coloured object, the blue is recorded in the lowermost portion of the layer, but is prevented by the orange filter from penetrating further. The green rays penetrate further than the blue, but are prevented by the orange filter from reaching the uppermost portion of the layer, and green is therefore recorded in the intermediate portion. The red rays pass right through the layer, and are recorded mainly in its uppermost portion.