toddstew said:
Donald, can you tell me a little bit about putting steel wool in exhauted fixer? I've got a big ol'barrel that I need to take care of.
Pretty simple -- go to the home improvement store and buy the steel wool they sell for wood finishing (comes stuffed in plastic packs about the size of a loaf of bread). For each gallon of spent fixer, drop in two steel wool balls, cover, and come back in a week. You'll find the interior of the container heavily plated in silver, and lots more silver sludge in the bottom of the container, while the steel wool will mostly have been eaten up by the reaction. Decant, or preferably filter the liquid through paper coffee filters or similar (slow going, give it time), and the clear or colored liquid that comes through the filter is effectively silver-free fixer with some iron added to the solution. That's the stuff that goes on the garden. Roses are said to love the stuff (they like sulfur, apparently, and iron doesn't hurt them a bit), but it should be good on tomatoes, squash, etc. as well; likely everything in a typical flower or vegetable garden will be okay with it if you dilute it a bit (say, with some of that wash water).
The sludge in the container is impure silver; if you're the DIY sort it can be melted (outdoors!) in a foundry and cast into ingots for later resmelting, or it can be reacted with nitric acid to make silver nitrate solution that will work just fine for a number of alternative processes such as salt prints, kallitype, van Dyke, etc.
VERY IMPORTANT that you do *not* do this with fixer that's been used after selenium toner!! That can be left in an open pan (where children and animals can't get into it) until all the liquid evaporates, and the residue treated as household hazardous waste (similar to old cans of paint, drain opening lye that's hardened, etc.); most communities have a means of safely disposing of the stuff, though they're almost certain to want to know what they're dealing with (you'd tell them "photographic fixer contaminated with selenium toner", which they will dutifully write down after asking you how to spell selenium).
glbeas said:
If you consider that sodium thiosulfate is put into fish tanks in very dilute concentrations to neutralise chlorine in the water I'd worry very little about using rinse water for watering the flowers.
Even more so -- the same chemical is used in swimming pools for humans (as is sodium sulfite) for the same purpose. If you don't tone your prints or use exotic developers, silver is the most toxic material in the printing darkroom, and once reduced to metallic form, it's nothing to worry about.