4-17. TEMPERATURES ABOVE 90F
a. General. When the temperature of the processing solutions is 90F or above,
sodium sulfate should be added to the developer solutions as indicated in table 4-8.
When the temperature is 95F, sodium sulfate should also be added to the hardening
bath. Once the sodium sulfate has been added, the bath should not be allowed to cool;
if its temperature falls 5 to 10F, the sodium sulfate may crystallize. The hardening
bath should be mixed fresh every 24 hours because, when partially used, the bath loses
its hardening properties rapidly.
SULFATE ADDED PER
GALLON OF SOLUTION
Rapid X-Ray Developer
* No modification of fixer required in this temperature range.
Table 4-8. Modification of developer and hardener solutions For high
b. Hardening and Fixing at Temperature Above 90F. X-ray film should
remain in the hardening bath for three minutes; during the first minute, they should be
agitated frequently to prevent the formation of a precipitate on the film surface. Next,
the film should be transferred to the fixing solution. In order to minimize exposure to the
air, the film must be transferred quickly from solution to the other.
c. Washing at Temperatures Above 90F. In washing the films, the flow of
water should be sufficient to permit washing for a period not exceeding 10 minutes.
Prolonged washing may cause the gelatin in the emulsion to swell excessively. In a
single wash tank, the hourly flow of water should be at least 15 times the volume of the
tank. In the two-compartment cascade washing system, the hourly flow of water should
be at least eight times the volume of one compartment.
4-18. TRAY PROCESSING
(1) When a tank is not available, films may be processed in trays, although
this method is not as efficient as the others that have been discussed.