The processing of photographic plates is a step in spectrographic analysis using photographic recording which should be simple, routine, and reproducible. The critical parameters are temperature, time, uniformity of agitation of solutions, and developer strength, which are usually controlled through the use of a mechanical processor coupled with careful darkroom practice.
T. B. Griswold, W. H. Dennen, and W. H. Blackburn, "A Photographic Plate Processing System," Appl. Spectrosc. 24, 460-461 (1970)