Safelight
A safelight is a
light source suitable for use in a photographic darkroom. It provides illumination only from parts of the visible spectrum
to which the photographic material in use is nearly, or completely insensitive.
Design
A safelight usually consists of an ordinary light bulb in a housing closed off by a coloured
filter
, but sometimes a special light bulb or fluorescent tube with suitable filter material or phosphor (in fluorescent tubes) coated directly on the glass is used in an ordinary fixture.
Differently sensitised materials require different safelights. In traditional
Panalure panchromatic paper is tolerant of limited exposure to light filtered through a Kodak 13 Safelight Filter.[2]
Other panchromatic materials must be handled only in total darkness.
Many photosensitive materials used in technical and industrial applications, such as
Low-pressure sodium vapour lamps sometimes are used in larger industrial darkrooms. They emit nearly monochromatic light at 589 nm (yellow), to which the materials are insensitive; as a result they can be extremely bright while still "safe".[citation needed
]
The word safe in safelight is relative, as in most cases, a sensitised material eventually will be affected by its safelight if exposed to it for an extended length of time.[3]
See also
References
- ISBN 0-240-51592-7
- ^ Kodak Professional Panalure Select RC Paper, Rochester, New York, U.S.A.: Eastman Kodak Company, June 2005, p. 1
- ^ "Fact Sheet: SAFELIGHT FILTERS AND DARKROOM LAMP" (PDF). Ilford. October 2002. Archived from the original (PDF) on 2011-07-23. Retrieved 2011-08-02.
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