Selenium and fix

[doublenegativeseb]

Had a mild chemical mistake yesterday when I accidentally poured some paper fix 1+9 into some weak selenium toner 1:24. It slowly turned into a black sludgy mixture, i tested it on some paper and just got a thin film of black sludge on the paper. my questions are first what's happened here? it's clearly a chemical reaction and I'd be interested to know what that was and secondly can it be used for anything or filtered and re-used?

thanks

 

[bsdunek]

Bummer! It mar be interesting to see what the chemical reaction was, but otherwise, pitch it. You ruined both the fixer and the toner. Any more use will just ruin paper.

 

[buzzworm]

Fix is a reducing agent, which in chemical terms means that it moves oxidized metals closer to their metallic state -- this is what is does in photo processing -- causes the unused silver salt in an emulsion to reduce to a different silver compound that is contained in the spent fixer. (Which is why dumping used fix down the drain is very uncool -- dissolved silver is not removed at the sewerage treatment plant and escapes into the environment and acts like any other heavy metal contaminate, e.g. mercury.) In this case, the fix has done the same to the selenium in the toner, causing it to fall out of solution.

In any case, both solutions are toast and should be disposed of (in a responsible manner, of course...)

 

[Rich Ullsmith]

Someone correct my chemistry if I got it wrong here, but . . .isn't the black precipitate silver selenide? Didn't he essentially tone the silver that was floating around in the fix?

 

[Rich Ullsmith]

Oops, me type before me read. Buzz just said that.

 

[Nicholas Lindan]

I think the cause is the acid in the fix precipitating the selenium. Prints that carry over small amounts of acid into the toner will slowly precipitate black specks in the toner.

Another reason that non-hardening alkaline fixers work better when toning prints in selenium. The non-hardening per-se isn't a help to toning, the reason for 'non-hardening' is that alum hardening agents have to be in an acid solution to work.

 

[doublenegativeseb]

Thanks very much, I suspected that the black sludge was some form of Selenium and this makes a lot of sense.