GB378394A - Improvements in or relating to films for photographic purposes - Google Patents

Abstract

A non-inflammable film support for photosensitive emulsions, more particularly for kinematographic use, comprises a layer of insoluble gelatin coated on each side first with a layer of rubber, and then with a protecting layer of celluloid, collodion or other varnish. The gelatin may be rendered insoluble with formaldehyde or alum which may be added to the casting solution or applied in solution to the cast layer. The casting solution may also contain a trace of glycerine. The casting operation may be performed by extruding the solution, at a temperature only a few degrees above its setting point, through a die on to a travelling polished and waxed metal band which is cooled before it reaches the die to a temperature considerably below the setting point. The cast layer may be drawn through alcohol to hasten drying, and then dried in a current of warm air. The gelatin film is then thinly coated with rubber varnish (e.g. a small percentage of rubber dissolved in petrol), and then with a celluloid, collodion, or other varnish which will take the sensitized emulsion. The varnished film may be passed between highly polished pressure rollers.