Understanding Neutron Radiography Reading V-Kodak Part 2 of 3

The exact quantity of replenisher can be determined only by trial and by
frequent testing of the developer. The replenisher should be added at
frequent intervals and in sufficient quantity to maintain the activity reasonably
constant for the types of radiographs processed. It is obvious that if
replenisher is added only occasionally, there will be a large increase in
density of the film after replenishing. By replenishing frequently, these density
increases after replenishing are kept at a minimum.
The quantity of the replenisher added each time preferably should not exceed
2 or 3 percent of the total volume of the developer in the tank. It is not
practical to continue replenishment indefinitely, and the solution should be
discarded when the replenisher used equals two to three times the original
quantity of the developer.
In any case, the solution should be discarded after three months because of
aerial oxidation and the buildup of gelatin, sludge, and solid impurities.
Charlie Chong/ Fion Zhang
Radiography in Modern Industry. Rochester, NY: Eastman Kodak Co. 1980