The effects of six common reducers and four common intensifiers have been studied on a high contrast positive emulsion, a fine-grained panchromatic negative emulsion, and a high speed negative emulsion. It was found that reducers generally injure resolution, cutting reducers most of all, although the simple persulfate reducer improves resolution at low densities. Intensifiers vary according to no general rule, and some have little effect on resolution. Most of them are somewhat deleterious at low and medium densities, the silver intensifier being least so, but all improve resolution at high densities. No evidence was found for Scheffer’s statement that a rinse in Farmer’s reducer will dissolve the resolved portion of the image without much affecting its density.
FRED H. PERRIN and J. H. ALTMAN, "Studies in the Resolving Power of Photographic Emulsions. V. The Effect of Reduction and Intensification," J. Opt. Soc. Am. 42, 462-466 (1952)