The fixer test solution is just P. Iodide. I put a drop in the fixer tray, if a little yellow-white puff appears and then dissipates I rotate the solutions. A ha'penny's worth of P. Iodide from the chemists is all you need: 5g in 25ml of distilled water is enough for 500+ tests.
Is it potassium iodine? The stuff you take if the bomb goes of and you want to prevent thyroid cancer? Also, does the fixer test affect film or prints or is it inert?
Thanks Gerald for the clarification. So if potassium iodide gets cloudy, the fixer is beyond exhaustion. As for fixing film, I double the time it takes to clear. Is that still a good method? For fixing prints, I use a 2 bath fixing technique where I fix my print in rapid fix for a minute then hold the print in a water bath for a second fix with fresh fixer for 5 minutes. Both seem to work for me.
Silver iodide is the least soluble of the silver halides. So when a precipitate forms, and remains even after shaking, the fixer is saturated with silver and should be discarded. However it is really not useable before this point. The best method is to record how many sg in of film or paper has been through the bath to determine when to discard it.
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