 The stock was of standard gauge and thickness, but it had a photographic emulsion coated on both sides of the film base instead of on one surface only.In color film processes such as Cinecolor and Prizma, two black-and-white negatives photographed through red and blue-green filters, or by an equivalent bipack method, were photographically printed onto opposite sides of the duplitized film.Because its emulsion was sensitive only to blue light, a temporary yellow dye incorporated into the film prevented each printing light from also exposing the emulsion on the other side.