i bought a darkroom kit a while ago for printing and with it i got a laod of chemicals. i have been using rodinal exclusively for the last few years but now i have microphen, perceptol,ID-11 and some PMK Pyro. to be honest im not up to speed with any of these developers but the pyro really interests me. the shots i have seen posted online look great (not sure how much of that is the pyro compared to the print). can anyone tell me how ebst to use it and how long the shelf life is? i have 2 batches that come in powder a and powder b.