The DARKROOM COOKBOOK, Third Edition

How Safe Is Your Safelight?
Richard Garrod
Planning a Darkroom 13
It is important to realize that no safelight is 100% safe because the spectral sensitivity of
materials does not cut off abruptly at a given wavelength. The effect on print quality is
compounded in the highlight areas when a print is exposed to an unsafe light and then
the exposure from the negative is added. This creates a density higher than normal on
the print and produces a degradation of the highlights. Photographic papers also have
a slight sensitivity to colors beyond their sensitivity range. The sensitivity of a paper
depends on the nature of its emulsion, so testing is very important.
Nothing is more disappointing than to see the beautiful high values of an image
degraded by a safelight that doesn’t provide the proper protection. What is needed is a
safelight testing procedure.
The procedure I use is as follows:
1. Turn the safelights off, without a negative in the enlarger. Using the fastest printing
paper you use and with a short exposure, produce a light-gray tone just clearly
above paper white. Brief testing will determine the correct exposure to produce
this light gray (Chapter 8, Les McLean: Pre and Post Flashing).
2. After the base exposure level has been determined, expose a fi nal sheet of paper,
but don’t develop it yet. All lights are still off.
3. Tape the paper emulsion-side up on a cardboard and set it over the developing
tray, with all lights still off. Place a narrow, opaque object like a ruler lengthwise
along the entire surface of the paper.
4. Cover a one inch section of paper and ruler with another piece of cardboard
of around 11 � 14 inches and give the pre-exposed sheet 2 minutes of safelight
exposure. Extend the cardboard another inch and give the remaining paper 2
more minutes of safelight exposure. Then, extending the cardboard each time,
give sections 4, 8, and 16 minute exposure. This will produce a pattern of exposures
of 0, 2, 4, 8, 16, and 32 minutes of safelight exposure.
5. Process the paper with the safelights off and evaluate the test. Find the exposure
time of the area that fi rst shows the ruler’s shadow. You will be safe to use the
safelight for about one-half of the safelight exposure time that produced the ruler’s
shadow.
As a result of this testing I found it necessary to replace all the safelight bulbs in my
darkroom with lower wattage bulbs placed about four feet above the trays. Bouncing
the light off the darkroom ceiling, assuming it is painted white, is another way to cut
down on too much unsafe safelight.