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Nov., 1945 PROCESSING OF 16-MM ANSCO GOLOR FILM 317
3 different colors simultaneously, rather than an individual color development for each layer.
The developing process for Ansco Color Reversal Film, given in Table 1, consists of 9 essential steps with washes and rinses interposed where necessary. After camera exposure, the film is given a negative development in a metol-hydroquinone developer, Table 2. This develops the negative tricolor separation images recorded in the emulsion layers. At this point, however, no color is formed because color can only be formed when the film is developed in the proper color-forming developer. After developing, the film is given a short rinse and is short-stopped in an acid short-stop bath to arrest any further development. From the acid short-stop bath, the film goes directly into a chrome alum hardening bath. After hardening, the film is transferred to white light for the remainder of the process.
A wash follows the hardener and during this wash, the film is exposed again. Second exposure is accomplished by exposing both the back and the front of the film to GE PS-25 Photon1 ood-type lamps. The color temperature of the light is not important. It is important, however, to have enough light intensity to expose completely all the remaining silver halides in the 3 emulsion layers.
During the second exposure, all silver halides in the film, which were not previously exposed in the camera and which did not develop in the negative developer, now become exposed and are ready for development in the color-forming developer. These silver halides make up the positive image. In the color-forming developer, this image is reduced to metallic silver by the action of the developer. Simultaneously with this reduction, reaction products — which always occur in developing — are produced. In a normal black-and-white film, these reaction products diffuse through the gelatin and are finally washed out in the developer and subsequent baths. However, in color film these reaction products combine with the color formers in the film and produce dye in proportion to the amount of silver halides which were reduced. Thus, as the 3 positive images in the film develop to metallic silver, 3 separate dye images are formed in situ with the silver images. Concurrently, therefore, a yellow image is produced in the top layer, a magenta image is produced in the middle layer, and a cyan image is formed in the lower layer. No color is formed around the negative image because this image is already in the reduced or metallic silver state and, consequently, no further reduction can take place.