Film & darkroom
How to test a darkroom safelight
Colour alone does not prove a lamp is safe for your paper.
Safelighting has to match the photographic material and the working arrangement. A light that appears dim to your eyes can still affect paper. Test it where the material is handled, with the bulb, distance and exposure duration you actually use.
A test of the whole arrangement
ILFORD’s safelight test compares paper receiving controlled enlarger exposure before and after safelight exposure. It can reveal changes in density and contrast. The maker also notes that filters age and that excessive bulb power or an unsuitable distance can cause problems. Follow the complete documented test, not a guess based on the lamp’s colour.
Evidence: Manufacturer guidance
Record the conditions
Our test record names the paper, filter, bulb, lamp position and distance to the working area. Add the date and the longest handling interval you intend to allow. Keep the resulting sheet with those notes. If you move the lamp, change the paper or replace a bulb, that earlier record no longer describes the full arrangement.
Do not generalise from paper to film
A safelight approved for one paper does not establish safety for unprocessed camera film. Use the film’s own loading instructions and complete darkness when required. Phones, watches and equipment indicators also belong in the room’s light check; they should not be invisible merely because they are small.
Sources & further reading
Sources for the specific facts and product descriptions above. Our worked examples, interpretations and practical suggestions are original editorial guidance.
- ILFORD PHOTO — testing your safelightsManufacturer guidance