Color Photographic Materials

Color Photographic Materials 

photosensitive materials (such as paper and film) used in color photography for the production of color photographic images, as well as reagents for the chemical processing of such images and supplementary materials.

Photosensitive color materials, unlike those used in black-and-white photography, are multilayered; they are usually composed of three primary (silver halide) and five to six supplementary layers on a common support, or base. Each primary layer records rays from one-third of the visible spectrum, that is, one primary color—blue, green, or red. The supplementary layers improve color separation, prevent halation, and protect the surface of the emulsion layer from mechanical damage. In addition to silver halides, the primary layers contain couplers, which form dyes (yellow, magenta, and cyan) during the development process, or prepared dyes in the given colors, which are decolorized during processing in the areas of the exposed and subsequently oxidized (bleached) silver image. After the metallic silver is removed, the color-separated negative or partial positive images are composed only of formed or residual dyes.

Depending on the method of image production, color photographic materials are classified as negative and positive (for the negative-positive process); reversal on which a color image is produced as a result of the color development of a reversal image; and positive-positive (color photographic materials with de-colorization of dyes). The most widely used color photographic materials are those designed for the negative-positive process: (1) 70-mm and 35-mm color film for professional cinematography— negative (for photographing), positive (for printing films), and duplicating (for preparing duplicate negatives of motion pictures for mass distribution); (2) negative and positive color film for professional and amateur narrow-gauge cinematography— 16-mm. 2 × 8-mm, 8-mm, Super-8 mm, and 32-mm (2 × 16 mm); (3) negative color film for professional and amateur photography—sheet film in various sizes and roll film (perforated and unperforated) in widths of 60, 35, and 16 mm; and (4) color photographic paper with various surfaces for printing positive images from color negatives. All negative cinematographic and still film for color photography is available in two types: for daylight photography (as well as the light of arc lamps and flash lamps) and for photography under electric incandescent illumination.

The reagents for the chemical processing of photosensitive color photographic materials, such as fixatives and bleaches, and supplementary materials are essentially the same as those used in black-and-white photography. The sole exception are the developing agents widely used in color photography, such as the p-phenylenediamine derivatives N,N-diethyl-p-phenylenediamine sulfate and N-hydroxyethyl-N-ethyl-p-phenylenediamine sulfate.

V. S. CHEL’TSOV