increase, decreasing the usefulness of inspection results. The radiographic film development process SHALL be
performed as close as possible to 68'F (20°C); taking into consideration chemical manufacturer's instructions. See
Table 6-16. Film SHALL not be left in the developer solution any longer than the prescribed time for its specific
temperature. Uncontrolled time and temperature during film development causes under or over development, which
reduces or eliminates useful information from being discernible on the radiograph. Developing/processing solutions
past their useful life should be disposed of properly. Check state and local regulations to determine proper method of
Table 6-16. Developing Time versus Temperature.
Metol or phenodone and hydroquinone will not develop when used alone. To produce any density on the film also
requires an alkaline solution. The alkali in effect "opens the door" and permits the developing agents to enter the pores
of the emulsion. The speed with which the "door opens" is determined by the amount and potency of the alkali. If too
much alkali is present, the developer will tend to produce chemical fog. But if too little is used, developing will be
retarded. Within these limits the stronger the alkali the more rapidly development will be completed. Some of the
alkalis used in developing solutions are sodium hydroxide, potassium hydroxide, sodium carbonate, potassium
carbonate and borax.
Developing solutions containing only the develop agents and alkali would rapidly be exhausted by oxidation from the
air. The life of all developing agents are limited by (1) the reduction of silver bromide to metallic silver, and (2) the
amount of oxygen absorbed by the developing agents from the air. However, there is a chemical whose inclusion in
developing solutions extends its useful life. This chemical, sodium sulfite, and oxygen have a natural attraction for
each other. The affinity is so great that when added to a developing solution sodium sulfite actually prevents oxidation
by air of the other components for limited periods of time. To assist in reducing oxidation of developing solutions the
following SHALL apply:
a. A floating lid, that matches the general configuration of the container, SHALL be used for
replenishment and, when not in use for development; manual processing developing solutions. The
floating lid SHALL be manufactured from a material that will not react with the processing chemistry.
It should also have a specific gravity less than the chemistry so it will float naturally. One material that
has these characteristics is polypropylene. The floating lid SHALL be used in conjunction with the dust
cover lid that fits over the top opening of the container.