(4) Sludge. As the developer is used, sludge gradually accumulates at the
bottom of the tank. This sludge may consist of insoluble calcium and magnesium salts
originally obtained from the water source; metallic silver reduced and removed from the
emulsion by the developer, gelatin, and dirt particles. The sludge does not interfere with
development unless it is present in large quantities. It can be easily siphoned from the
bottom of the tank.
(5) Slime. Some kinds of bacteria grow on the accumulated gelatin in the
developing solution despite its alkalinity. Evidence of this growth is slime on the walls of
the tank. Sometimes the slime floats in the solution and adheres to the surfaces of films
being developed. The remedy is to thoroughly clean the tank before making new
solution. After scrubbing, use a solution of sodium hypochlorite, then rinse thoroughly.
b. Effects on Radiographs. These effects may be manifested in several ways:
(1) Uneven development. Evidence of uneven development may appear in
the form of streaks. Probable causes may be the use of a very short developing time,
insufficient agitation during development, incorrect high temperature processing
procedures, use of exhausted acid rinse and fixing solutions, or failure to agitate films
when first immersed in the fixing bath. The remedy lies in the use of correct processing
methods.
(2) Chemical fog and stain. Chemical fog and stain are usually the result of
using exhausted developer solution, contaminated fixing bath, or dirty developing
hangers.
(3) Blisters and reticulation. The formation of blisters and reticulated
emulsion is usually the fault of improper high temperature processing. Reticulation is
usually the result of transferring a film between solutions possessing wide temperature
difference. Physical distortion of the emulsion usually takes place under such
conditions.
3-61. SECONDARY CHARACTERISTICS OF FIXER SOLUTIONS
a. Sludging. An excess of developer carried over into the fixer solution tends to
participate some of the hardening agent. The result may be a white sludge in the
solution or a white scum on the films. This sludging may be prevented if films are
thoroughly rinsed in flowing water between developing and fixing. The films should then
be adequately drained so that a minimum of developer-contaminated rinse water is
transferred to the fixer.
b. Streakiness. Uneven density or streakiness in uniformly exposed areas may
result if films are not rinsed before fixing and not agitated during fixing. This is due to
the fact that one or two minutes may elapse before the alkali in the developer carried
over by the films is neutralized by the acid in the fixer solution. During this time,
MD0954
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