(2) To replenish using the topping-off method, .3 gallons might
additionally be removed from the tank and replaced with one-half gallon
replenisher solution, bringing the activity and the physical level of the
solution back to its original state.
(3) While this is a fairly simple method of replenishment, it does not
adapt well to continuous processors. If a long (500 - 1000 ft) roll of film is
being processed, the solution activity would gradually decrease during
processing. As a result, the end of the roll would receive less development
than the beginning.
b. Bleed System.
(1) In order to maintain the activity at a constant level during
processing, the bleed system is used. In this system the replenisher solution
being added forces a proportional amount of used developer solution out of the
tank through an overflow at the top.
This method, therefore, provides
continuous replenishment during processing, and, if the replenishment rates are
properly established, the gamma of the film at the start of processing and the
gamma at the end will be the same.
(2) The replenishment rates used are dependent on many factors. Among
them are: the chemical composition of the solution, the type of film being
processed, the size (width) of the film, the machine processing speed (time),
and the overall density of the film. If a film is overexposed and produces a
dense negative, it will use up developer more rapidly than a normally exposed
film. Since this is frequently not known until after the film is processed,
adjustments may be necessary after processing or during the next run.
film is underexposed (thin negatives), normal replenishment would be excessive
and, again, adjustments will be necessary.
a. As the film is transported from tank to tank, solutions are carried
over which will cause contamination or dilution. A squeegee is used to remove
most of the fluid from the film surfaces to minimize carryover.
It is also
very important to remove excess water from the film before it enters the drying
b. There are three general types of squeegees: blade, roller, and air.
Their use will depend on the complexity of the particular processor.
(1) Blade squeegee.
This type consists of two rubber blades which
resemble miniature windshield wipers mounted so that the film passes between
(2) Roller squeegee.
Depending on the processor, this type will have
two or more rollers to remove the liquid as the film passes between them.
(3) Air squeegee.
The film passes between two closely spaced nozzles