Solvent

Halation

An anti-halation backing is a layer found in many photographic films—and almost all film intended for motion picture cameras—usually a coating on the back of the film base, though it is sometimes incorporated between the light-sensitive emulsion and the base. Its purpose is to absorb light that passes through the emulsion, thus preventing any light from being reflected back through the emulsion from the rear surface of the base, or from anything behind the film, such as the pressure plate of the camera. This prevents a halo-like effect (halation) from forming around bright points or edges in the image. Still cameras, which handle less film and thus contend with less wear, typically hold their film in the gate with components painted or treated to be black, s… more »