3-17. MIXING PROCEDURE
Water should always be poured into the tank and the chemicals added slowly
while the mixture is stirred vigorously. In this way, the chemicals dissolve rapidly. (To
ensure the proper concentration of solution, the volume in gallons of the tank used
should be determined mathematically.) Sufficient water should be added to bring the
solution to the correct volume and temperature; thorough stirring is necessary to mix the
cool water with the chemical-laden solution. Solutions should not be used until all the
chemicals are thoroughly mixed and at the optimum temperature of 68F.
3-18. SOLUTION STORAGE
If the solution is not for immediate use, it should be placed in a clean brown
bottle of the proper size, well stoppered, and labeled plainly. Developer should be
stored away from radiators, as heat may cause deterioration of the solution.
3-19. MIXING WITH SEAWATER
While not recommended as a routine procedure, seawater can be utilized in the
same quantities as fresh water to compound x-ray developers and fixing baths. The
resulting solutions are turbid but will clear on standing. It is best to allow the solutions to
stand overnight and to decant the clear fluid for use. If turbid solutions are utilized, it is
essential that the surfaces of the film be carefully wiped off with a soft wet cloth or
photographic cellulose sponge after washing and before drying in order to remove any
deposit.
3-20. THE METHOD OF PROCESSING
The tank method of processing is efficient and convenient. Its most important
advantage is that it provides facilities for maintaining constant temperatures and for
preserving the solutions. Tanks containing the processing solutions are located in a
master tank containing water at the prescribed temperature and sufficient space is
provided for film rinsing and washing. Water should be circulated in the master tank at
a temperature that is controlled by a mixing valve situated in the hot and cold water
supply. If the volume of radiographic work justifies it, a separate tank used only for
washing purposes should be provided.
3-21. THE DEVELOPMENT PROCESS
As the film is first lowered into the developer solution, it should be rapidly moved
up and down a few times to remove the air bells (small air bubbles) from the film. If
these were not removed, the film would not correctly be processed at those points.
After an exposed x-ray film is placed in the developer, the gelatin in the emulsion
becomes swollen and porous due to the presence of water and the activity of the alkali
in the developer solution. The exposed silver bromide crystals have become ionized
and the reducing agents can attack them. The x-ray exposure causes the sensitization
MD0954
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