c. Compensation for Aging. When solutions stand for some time without
use, such as over a weekend, it is necessary to make allowance for the
decrease in activity of the developers. For a two-day shutdown, try adding
developer replenisher at the rate of three percent of the developer tank
solution (1 gallon solution - 3.84 ounces).
d. Special Treatment Required for Bleach Solution. The efficiency of
the action of the bleach depends upon a certain amount of aeration of the
The best way to achieve this aeration is to use
airburst agitation. An alternate method is to introduce air from a separate
compressed air supply, such as the Kodak gas distributor sparger.
should be done for about 30 minutes before each process at a valve pressure
of about 2 1/2 pounds per square foot. Since it is not possible to over-
aerate the bleach, it is recommended that low-level aeration continue
throughout the day.
Even well-mixed and properly replenished solutions will become exhausted
with age. Ensuring proper control of your chemistry includes discarding old
chemistry. Figure 2-7 gives the useful life of C-41 chemistry.
Useful life of C-41 chemistry
After mixing color processing chemistry and prior to film processing, an
analysis may be made of the solutions.
This analysis would require the
performance of the following tests: determine the specific gravity (SG),
determine the potential hydrogen (pH), and run a sensitometric check.