Patent GB-272986-A (GB)
Title: Improvements in kinematograph color films and methods of manufacture
IPC: G03B33/00
Filed: 1926-03-18
Abstract: 272,986. Thornton, J. E. March 18, 1926. Drawings to Specification. Colour kinematography. - Relates to the production of two-colour films of the kind built up by cementing together back-to-back two component thin celluloid or like films carrying respectively orange-red and blue-green colour-record images which are formed side by side as transparent colloid reliefs on wide sensitive film material. According to the invention (1) double-width sensitive film-material is used, carrying two parallel stripes of ready-coloured sensitive colloid such as gelatin, glue, albumen, &c. containing mordanted dyes or pigments, and may be reinforced or not on its colloid face with a strippable layer of paper, as in Specifications 213,647, and 214,934, [Class 98 (ii), Photographic processes &c.]; (2) the colloid is sensitized with bichromate and, after printing the component image-series through the support from a double-width negative or printing clichÚ, or from two single width negatives &c., under a strong artificial light in apparatus as described for example in Specification 14901/14, [Class 98 (ii), Photographic processes &c.], the printed images are masked, and the unprinted margins of the two components are exposed to light; (3) the double-width film is developed without folding and before cementing, with hot water, bichromate solution, &c. in apparatus as described for example in Specification 28875/12, [Class 98 (ii), Photographic processes &c.], in order to etch away the unexposed colloid, and leave coloured colloid relief images and also the full thickness of colloid at the margins of the prints; (4) the film is dried and slit into the two components, which are united by applying to the back of each a thin layer of stiff slow-drying cement, such as celluloid dissolved in amyl acetate in the case of celluloid films. and pressing the components together back to back, the operations being performed in apparatus referred to in the Provisional Specification or as described for example in Specifications 232.302 and 12229/12; (5) correct assembly before cementing is facilitated by providing identification marks on each component film: (6) the films are registered in the printing, cementing &c. operations bv a single registration hole adjacent to each picture as in Specification 233,991, and the traction perforations are perforated preferably after completion of the cementing operation; and (7) the film is treated with glycerine or chrome alum solution, or is coated on both sides with a colloid varnish containing glycerine or chrome alum. or both. The coloured colloid stripes on the sensitive film material mav alternatively be red and blue nrovided that the film is bathed after develonment in a yellow dve. The finished film requires no trimming, since it is of the usual standard width after cementing. If the film supports are of the non-flam cellulose acetate type, the cement employed is made bv dissolving the cellulose acetate in the heaviest solvent of that material. Specifications 14340/12, 25084/12. and 213,866 also are referred to.