Thank you Pete. I used my schoolboy chemistry to check this. I hadn't thought of doing it this way, but it makes sense. Your calculation is correct (the sod. thiosulphate quantity refers to the anyhdrous form), and for 1000g of ammonuim thiosulphate, you need 1080g sod thiosulphate. This also produces 800g of sodium chloride, which one would guess is probably benign. However, on Jack's Photographic and Chemical Site (www.jackspcs.com) he states for sodium chloride:(posted 8427 days ago)Uses: As an ingredient in the precipitation of photographic emulsions; as a silver halide solvent in fine grain developers; as an ingredient in reducing and toning solutions; as a washing aid to eliminate residual thiosulfate from silver images.
A silver halide solvent is not exactly what I'm looking for in maximizing the effects of PMK. In a rapid fixer, would it have any discernible effect?
Thanks to all for their interest in responding