Patent GB-360819-A (GB)
Title: Process and means for producing sound motion picture films in colour
IPC: G03C7/24
Filed: 1930-05-27
Abstract: 360,819. Photographic processes and apparatus. MULTICOLOR FILMS, Inc., 201, North Occidental Boulevard, Los Angeles, U.S.A. May 27, 1930, No. 16282. Convention date, June 17, 1929. [Class 98 (ii).] Relates to processes for making a coloured motion-picture film, having two superposed sets of picture images in complementary colours, and a photographic sound record in addition. According to the invention, the sound record and one series of picture images are chemically toned to one colour, and the other series of pictures are toned to the complementary colour. Preferably the sound record and one series of pictures are toned blue, and the other series of pictures red, by means of iron and uranium toning solutions respectively. In producing a positive on a film having a sensitized layer on each face of a celluloid base, printing is effected on the layers on opposite faces of such a film from two negatives simultaneously, one negative having been exposed through a blue filter and the other through a red filter, the sound record preferably being formed on the margin of the latter negative. Both layers of emulsion on the positive film are initially impregnated with a light-restraining dye, to permit of the simultaneous printing, for which the apparatus diagrammatically shown at 20 . . 25 in Fig. 4 may be used. The positive film 12, on emerging from the printing apparatus, passes through a series of tanks 26 .. 29 containing respectively a soft tone developer, a " stop " bath of acetic acid, fixing solution and water, after which the film is dried by air jets 40. That side of the film which was printed from the negative taken through a red filter is then subjected, in a tank 30, to a solution which converts the silver images into a blue compound. A formula for a suitable iron toning solution is given. After leaving the tank 30, the film passes through washing tanks 31, 32, 33, Fig. 4a, then into a tank 34 containing a uranium toning solution (a suitable formula being specified), in which the complementary images are toned red ; and finally after being fixed and washed in tanks 35, 36, 37 the film passes through a drier 38 to a take-up reel 39. A portion of the finished film, shown as having the selectively coloured emulsions 13, 14, partially detached from the celluloid base 15, is illustrated in Fig. 2. The application of the invention to the production of a positive film having an emulsion coating on one side only is described, the two series of coloured picture images and the toned sound record being formed in a single thick layer, or in two superposed layers. The images to be toned red are printed on the outer part or layer of the emulsion, and the images and sound record to be toned blue are printed through the base on to the inner part or layer of the emulsion. After printing, developing, and drying, the film is immersed in a mordant (two formulµ for suitable solutions containing copper and iodine compounds respectively being specified), and is then treated with red dye, and washed. Finally, the film is immersed in a blue toning bath, which tones the inner picture images and the sound record without affecting the outer images that have already received the red tone.