conditions under which the scale was formed. Fill the tank with stop-bath solution and
allow to stand overnight. A strong stop-bath solution can be prepared by adding
16 ounces of 28-percent acetic acid to one gallon of water. To make 28-percent acetic
acid, combine three parts alcohol acetic acid with eight parts water. If this stop-bath
solution does not loosen the scale, try a five percent solution of hydrochloric acid. Be very
careful, as the acid solution can pit stainless steel.
c. Wash tanks often become coated with algae that may stick to the film.
Thorough cleaning and weekly treatment with commercial bleach solution consisting of
one part bleach to six parts water, removes algae. Be sure to cover the inside of the
intake and overflow pipes with the solution, since algae often grows there. Leave the
solution in the tank overnight; drain, scrub, with a stiff brush; and rinse four or five times.
2-10. THE FILM DRYER
a. The drying of radiographs is always important. The dryer is fitted with heating
elements and a large fan, both on the same circuit. The dryer duct should vent outside the
building to prevent excessive humidity.
b. The small processing room in which only a few films are processed daily usually
does not justify installation of a dryer. In such a case, a commercial drying rack is
adequate. When a commercial rack is not available, a one-by three-inch board can be
drilled with three-eighths inch holes, about four inches apart and mounted on a high wall.
c. The drying unit may be installed along the wall at one end of the processing
room or underneath the loading bench. The drying of films is usually considered a "wet
film" operation, but with reasonable care can be carried out at a low location on the "dry"
side of the room.
d. When air is drawn in rather than blown through the dryer, a uniform air flow
results. Airflow should be at least 450 to 500 cubic feet per minute. Air temperature inside
the dryer should be maintained at the coolest temperature that will dry the film--never
more than 120F. Heating elements and the fan should be on the same circuit.
e. Suitable insulation is placed around the dryer so that the temperature of the
room is not unduly affected. The drip pan underneath each film drawer should be kept
clean and free of dust and debris.
Section II. PROCESSING ACCESSORIES
Processing accessories should be kept near the section of the processing tank
where they are used. Time-temperature guides, exhaustion charts, and other processing
information are readily referred to when fastened to a chart board placed near the
developing tank. A shelf for the interval timer and thermometers should be located near
the developer section. Other accessories may be placed on shelves above and behind
the processing tanks.