Re: Screwed up Silver
Date: July 16, 2010 01:56PM
I have ruined silver baths before, but you can recover something. My first plates that I ever japanned plates were galvanized, and I didn't take the zinc off... the silver nitrate ate all the zinc off and the zinc ruined the bath. I simply filtered out the zinc and then sunned the bath.
Sunning is frowned upon in some circles, but I have found that it works if you need to do it, like you have contaminated the silver somehow. As I progress in the photographer's art, I find I don't need to sun my baths any more. Also, avoid buying technical-grade silver nitrate. I bought cheap silver nitrate and I had to sun my bath after every session. When I switched to expensive (read, uncontaminated) AgNo3, I never had any more problems!
To sun, Pour the bath into a clear container (cut off milk jug) and set it outside for several hours. If it is badly contaminated, the whole bath will turn inky dark as soon as you put it in the sun. Then the black gunk will settle to the bottom. Leave the bath out until it is completely clear, and then decant the bath back into your bath container through filter paper. You can test the bath with a hydrometer to make sure it's at 9%- if it isn't add a little AgNo3 crystals to bring it up again.
A Ph test is handy, but as long as the bath is a tad acidic, it should be fine. If you have punched up your bath with a little drop of nitric acid, it should be fine. I've never had to add more acid after I added a drop or two when I first made up a bath. I don't know how one would de-acidify a bath... add some sort of alkali? This would produce a salt that would precipitate out of the bath and/or ruin the bath's effectiveness. I wouldn't want to try it!