Safelight

Part of speech: noun

Definitions

1. A dim colored lamp used in a darkroom that lets photographers see while leaving light-sensitive film or paper unexposed
2. The filtered lamp in a photographic darkroom whose low-intensity, safe wavelengths allow work with unprocessed film without fogging it
3. A special darkroom light, usually red or amber, that illuminates the workspace without damaging photographic materials during development

Etymology: "Safelight" is a plain compound of "safe" and "light," and its meaning is literal: a lamp that is safe to use in a darkroom because its colored light does not expose photographic material. The point of the word is that the light is safe for the film or paper being developed, so the photographer can see the work without ruining it. The "safe" here carries its older sense of "not harmful or dangerous," which is the same sense found in "safe" as in "out of danger." In photography, the danger is chemical rather than physical: light-sensitive emulsions darken when exposed, so a lamp was "safe" only if its wavelengths left them untouched. Red and amber filters became the usual choice because film of the period was far less sensitive to those colors than to blue and white light.