I'm shooting a homemade dryplate emulsion and I'm interested in making ambroypes. So instead of my sodium thiosulfate fixer, could I use a potassium cyanide fixer to cause the silver to lighten? Also, can a potassium cyanide fixer be reused? Does a potassium iodide hypo check solution work for checking for exhausted fixer? Does a 2 min wash with 3 exchanges of water remove enough pyro so that i won't kill my self with chlorine gas? I intend to fix outdoors anyways.. Currently I'm not fixated on historical accuracy, is there another way to lighten the silver deposits?