It is common in wetplate collodion to "sun" the silver bath to remove organic impurities (and ether & alcohol) which make their way into the solution during normal use. After filtering this stuff out, the sensitizing baths are again good to go. So, even if your solution gets a bit contaminated I suspect you can extend its life almost indefinitely.
I've also added a teaspoon of kaolin to a dirty bath, shook it up and let the gunk settle out dragged down by the kaolin, and then after siphoning (with a siphon pump, not by mouth which is dangerous with this chemical) ended up with a perfectly clear usable solution of it again.
I've also reconstituted silver nitrate crystals that had to be at least 90-100 years old.
Last edited by smieglitz; 08-08-2006 at 09:16 AM. Click to view previous post history.