Geoffrey Crawley wrote (Amateur Photographer 17 Feb 07) to the effect that the sharpness of FX-37 is the result of the combination of borax and carbonate as alkalis.The carbonate beefs up the the softness given by the borax without a noticeable increase in grain.This is helped by the milder solvent effect of the reduced sulfite content.The formula could be described as a "sharpened-up" D76 with phenidone instead of metol.