GB123787A - Improvements relating to Colour Photography. - Google Patents

Abstract

123,787. Hamburger, A. Dec. 3, 1917. Colour photography; toning and after-treatment; trays, dishes, and containers for flat flexible films. - Complementary colour record negatives are accurately superposed on opposite sides of a film which is sensitized on both sides and are then printed. The images are coloured practically simultaneously, and the coloured film is preferably combined with a yellow positive to produce a finished picture. The. negatives are preferably made in a camera embodying the invention set forth in Specification 28722/12, both negatives being thereby produced simultaneously and one of them being reversed. The positive images may be printed simultaneously and may then be bleached by the well-known Traube method or in a solution made up as folows :-2 fluid oz. of a solution of 1 oz. nf potassium iodide in 9 oz. of water are added slowly, and with stirring, to 4 fluid oz. of solution of 1 oz. of potassium bichromate in 9 oz. of water; 16 oz. of water containing 80 minims of hydrochloric acid are then added. After bleaching, the images are dyed simultaneously by means of the frames a, a<1>, which form closed tanks in conjunction with the film. The frames are hinged together, and the frame a' fits into the rebate of the frame a. Each frame is provided with rubber or the like b, b<1> which engages the film c to make a tight joint, and with sheets of glass d, d<1>. Inlets i, i<1> and air-exit valves k, k<1> are provided on each frame, and small reservoirs to take up liquid displaced from either tank when one tank is filled after the other, may be provided. The two frames may be held against the film by means of wing-nuts and screws f. After dyeing, the images are fixed with hyposulphite of soda containing 5 per cent of tannic acid. The yellow positive may be obtained by the process described in Specification 20880/11. The bleaching and colouring of the images may be effected in one operation by pressing into contact with them carbon paper or dye gelatine paper, which has been soaked for a time, say five minutes, in a solution as follows :-Copper sulphate, 4 oz. ; potassium bromide, 1400 grains; potassium bichromate, 180 grains; hydrochloric acid, 80 minims, in 40 oz. of water. The silver images while in contact with the treated carbon or dye gelatine papers are bleached, coloured, and hardened, and the soft gelatine is afterwards dissolved in hot or cold water, the papers floating away and leaving the coloured images free on the films. Specification 123,786 also is referred to.