Salt as a fixer

[flyinghamster]

Hello all,

Just wondering if anyone has ever used salt as a fixer.
I've been thinking about trying out caffenol, and I also thought about having a go at using salt as fixer (for photo paper to be clear, rather than negatives). I've seen that if you use the right amounts and a warm temperature it can work (although I don't know how long the photo will last, but still, just an experiment to see what happens).

Anyway, my question is, if I did go about using salt water as a fixer, Im assuming the fixer will still end up with silver in it, just like standard fixer, because of the way it works, which I spose means I can't just tip it down the sink? It's not that easy me to get to a proper disposal place (no car), could I just do something like put the used salt fixer in cat litter and then chuck it in the bin? Or am I over thinking it, should I just put it down the drain?

 

[webestang64]

I've never used salt fixer but all my standard fixer gets run through a silver recovery unit at work. I would never put fixer down a drain otherwise.

 

[Rickbb]

It’s always a bad thing to dump dissolved metals down the drain, even silver can be toxic.

For small quantities for us home users, after recovery of the silver, neutralize the ph then dilute with lots of water. Large commercial users need permits and certificates to show a clean discharge in most places in the world.

Besides you can put a decent amount of cash back in your pocket with the recovered silver. Spot price of silver as of this writing is $24 a Troy ounce.

The fixer itself is a salt, sodium thiosulfate, which is not classified as hazardous at all so would be less of an issue to dump. After the above treatment of course.

You can save up the fix and recover the silver by simply hanging a piece of pure copper wire or bar in the bottle/jug/tank, the silver will build up on the copper. When no more silver will “plate” out on the copper it’s clean enough to neutralize, dilute and flush.

 

[bulldurham]

Whereas the older fixers mostly consist of Sodium Thiosulphate, the newer, more commonly used Rapid Fixers also contain Ammonium Thiosulphate which can cause severe gastronomical/eye/skin effects if ingested or you have surface contact. I would caution anyone using photographic chemicals to treat all of them as potentially hazardous.

 

[flyinghamster]

Thanks everyone, it confirms my suspicions that I shouldn't just pour it away. The copper in a bottle sounds like a nice idea, thanks.