which will depend upon the amount of illumination desired and the angle of which it must
fall. An indirect safelight should be used at the loading bench because of the possibility of
fairly long exposure o the film to this light.
(3) Safety standards. No safelight is safe if film is left under it too long. Film
that cannot be processed immediately should be kept in a lightproof container. Films
awaiting processing should be protected by screens, not piled near a safelight.
(4) Checking safelight illumination. A simple method for checking the safety of
illumination is to cover part of a film with cardboard and then expose the remainder for one
minute at a distance of three feet. This test film is then developed. If no fog shows on the
exposed part as compared with covered part, the lighting may be assumed safe. If fog
appears, the safelights are not functioning properly. All safelights should be tested
periodically for light leaks, fading of the filter, and excess wattage.
c. Wet Film Illuminator. In manual processing, a foot switch-operated illuminator
mounted above and to the rear of the washing tank is convenient for the inspection of
radiographs during the course of hardening and washing (item 18, figure 2-2). The light
can then be easily controlled without use of the hands. The illuminator should not be used
when unprotected or when unprocessed films are on the loading bench nor should it be
used for films that have not yet been cleared in the fixer solution.
d. Wall Finish. If the quality of the light from a safelight is "safe," the illumination
reflected from any surface is also "safe" regardless of the color or finish of the surface.
However, the finish should be an attractive color and should reflect the maximum amount
of safelight illumination. To avoid glare, flat paint should be used. Maximum reflection is
achieved by choosing a color within the same color spectrum as that of the safelight. In
permanent installations, the ceilings and the upper 18 inches of sidewalls should be
painted white. The remaining wall surfaces should be a warm, light color.
a. Satisfactory ventilation of an x-ray processing room requires consideration if the
health and well being of the x-ray specialists are to be maintained. The processing room
is subject to certain conditions that directly affect the air in it: uncovered solutions
increase the humidity in the room, processing solutions create odors, and film-drying
cabinets give off heat.
b. When not properly controlled, temperature and humidity have adverse effects on
both the worker and the film. For comfort, humidity between 40 and 50 percent,
temperature between 67 and 83F, and air movement between 15 and 25 feet per minute
should be maintained. Greater air velocity would be tolerable at temperatures above 80.
The air in the processing room should be maintained at a positive pressure, that is, air
should be pumped in, not out. This helps prevent the entry of dust. The dryer should