LESSON 1
b. The quantity of film may also affect the processing method you
choose. If you have 16 rolls of 35 mm film, you could process it in the
daylight tank, but you may have to make two processing runs. Better
uniformity is achieved and larger quantities of film can processed in an
open tank.
c. In some cases, the method is a matter of preference. You can
process rolls of 120 or 35 mm film in an open tank or a daylight tank. Most
photographers prefer to use the daylight tank for small quantities of film.
d. Following is a chart showing the processing methods available for
different sizes of film and the maximum quantity you can process in each (at
the same time). For example, 35 mm film can be processed in a daylight tank
(64 oz) maximum quantity of 8 rolls or it can be processed in an open tank
(3 1/2 gal), maximum quantity 36 rolls.
NOTE: When we speak of processing 36 rolls of film in an open tank,
we are referring to film of the same type, such as TRIX. You
cannot process 15 rolls of TRIX with 15 rolls of PANX, because
they have different processing times.
e. Once the method is determined, you must make sure that the equipment
is free of old dried chemicals. These particles may fall onto the film
emulsion while loading the film into equipment and cause "spots" on the
film.
3. The processing sequence. Processing consists of a series of steps that
will develop the invisible image into a visible image through the use of
chemical solutions.
a. Let's assume that you have determined the type of film you are
processing and the method you will use to process it. The steps in the
processing sequence (fig 17) are as follows:
(1) Presoak. The presoak is an optional but very useful step in the
processing sequence. Prior to developing, the film is immersed in water to
soften the emulsion, assisting the rapid penetration of the developing
agent.
(2) Developing. The exposed film is immersed in a chemical solution
(called developer) consisting of a developing agent, buffer, accelerator,
and preservative. This starts the chemical action changing the exposed
silver halides to a black metallic silver.
(3) Stop bath. This step stops the action of the developing agent,
preventing further development. Acetic acid is commonly used. Since the
fixer also contains an acid, any carryover prolongs the life of the fixer.
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