Figure 10-13.–Sheet film tank processing agitation.
The air bubbles that usually occur when dry film
is immersed in a solution can be removed without
harmful effects in the predevelopment water rinse.
When the water-softened emulsion is placed in
the developer, the action of the solution begins
uniformly over the entire emulsion. Thus uneven or
streaky development is avoided.
The predevelopment water rinse removes the
antihalation backing dye that interferes with the action
of some developers.
The predevelopment water rinse brings the
temperature of the film and the hangers to the processing
temperature. Maintaining constant temperatures in all of
the processing solutions is very important.
The predevelopment water rinse is given by
immersing the loaded hangers in a tank of water and
agitating them for about 2 minutes. The temperature of
the water should be the same as that of the other
processing solutions. The loaded hangers are then lifted
out of the water, drained by one comer, and processed
in the usual manner.
Immerse the hangers in the developer slowly and
smoothly to avoid splashing or the formation of air bells.
Air bubbles usually result when films are immersed
rapidly, especially when a predevelopment water rinse
was not used. All the hangers should be immersed
simultaneously to assure uniform agitation and
development.
Strike the hangers sharply against the sides of the
tank several times to dislodge any air bubbles that may
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