I have acquired some Dimezone-S which is reputed to be a better-keeping variety of phenidone. I'm interested in knowing if anyone has tried it, and if so any advice about equivalent quantities. Someone on the old pure-silver list suggested that I substitute equivalent molar weights (i.e. multiply the recipe's amount of phenidone by about 1.15). He had also done some tests in a very different developer to compare the two versions and found that this conversion worked for him. Leaving aside the potential for weighing inaccuracy with comparatively small amounts of this chemical, how critical is the amount of phenidone in Pyrocat-HD? The reason I'm trying this is because I'm using the metol version of Pyrocat-HD since my first attempt with phenidone didn't work at all well. Maybe that batch of phenidone was bad, since all the other ingredients worked very well in the metol batch that I mixed up. The metol version is great, but a little more speed would always come in handy!