Caffeine doesn't help my mental alertness...(posted 8160 days ago)I haven't done experimental analysis, but it makes sense that you get higher shadow contrast with p-aminophenol than with phenidone in dilute solution with very little sulfite. p-aminophenol will receive more restraining effect of halides whereas phenidone is less susceptible to restraining effect. I think this is another reason why phenidone developers tend to be less sharp than metol counterparts. If you make pyrocatechin alone developer, or pyrocatechin-metol developer, my guess expects to see higher shadow contrast.