Anti-halation layer.

An opaque colour dye applied to the back of most film stock. This layer absorbs light and prevents light from passing all the way through the film.

Without such a layer light travels through the film, hits the pressure plate inside the camera and then bounces back into the film again. The result causes a glow - halation - around bright objects. The layer is washed away during developing, which is why developed film is clear but undeveloped film is opaque.

Kodak HIE infrared film is the most popular film available today which lacks this layer. The result is an ethereal glow around bright areas, which is part of the popularity of the film. Masking film used in contrast masks also lacks an anti-halation layer.

cf. contrast mask, halation, infrared film, opaque, pressure plate.

Entry last updated 2002-04-27. Term 65 of 1487.

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