(3) Place the film on the film holder. The film should be held lightly by its
edges to avoid the appearance of smudges or fingerprints on the developed film. They
may appear even when the hands are clean.
(4) Set the interval timer (clock) for the prescribed developing time. Timer
should start when the film is placed in the developing solution (developer).
The recommended temperature for the developing solution is 68 F (20 C).
At this temperature, most films should be left in the developer exactly 4 1/2
minutes. Without adequate equipment, 68 F (20 C) cannot always be
obtained. In that case, the time factor should be adjusted according to the
chart in figure 3-5. Temperatures above 70 F (21C) and below 60F
(15C) should be avoided if possible.
Figure 3-5. Time-temperature ratio for processing film.
(5) Immerse the film in the developing solution (figure 3-6), moving the film
holder up and down several times to break up air bubbles that may have formed on the
surface of the film.
If bubbles are allowed to remain, they prevent the developer from acting on
the area of film contained in each bubble. Also, care should be taken to
ensure that the film does not touch another film or touch the sides of the tank.
Such contact affects the emulsion and prevents the developer from acting
upon it properly.