anti-halation backing

An anti-halation backing is a layer found in most photographic films.

A piece of film consists of a light-sensitive emulsion applied to a tough, transparent base, sometimes attached to anti-halation backing or "rem-jet" layer (now only on camera films).

A Lippmann plate is a clear glass plate (having no Anti-halation backing), coated with an almost transparent (very low silver halide content) emulsion of extremely fine grains, typically 0.01 to 0.04 micrometres in diameter.