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Comment by ginko | Hacker News Reader

Alternative processes are pretty cool, but you still need regular fixer for fixing the final image. That's by far the nastiest chemical in b&w chemistry and can't really be replaced. I've once read you can get a similarish result by essentially storing the film in rather concentrated salt solution for several hours to days, but that doesn't seem quite practical: http://www.filmwasters.com/forum/index.php?topic=7958.0

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Are you talking about sodium thiosulfate? It's less acutely toxic (oral LD 50) than table salt in animals, has no known chronic health risks, doesn't persist in the environment, and is non-flammable.

Yes, but once it becomes laden with powdered, precipitated silver it is far less benign. Silver is still a heavy metal after all, even if it is not the most acutely dangerous one.

The problem then is the dissolved silver, not the thiosulphate.

And just evaporating it down should be a suitable concentration step, if not just electroplating the silver out of solution with a graphite anode or something like that.

This is true with regards to fresh fixer but, once it's used it contains silver which, as reported by, sciencedaily.com:

"We found that silver nanoparticles are extremely toxic. The nanoparticles destroy the benign species of bacteria that are used for wastewater treatment. It basically halts the reproduction activity of the good bacteria."

I photograph onto paper, develop with caffenol, digitize after the stop bath (quickly) and discard the paper so as to avoid using fixer. Yes, there is silver on that paper but I'm hoping that silver in an incinerator or even landfill is better than silver in the wastewater.

Back in the day when analog photography was just called photography, there were inexpensive silver recovery filters available. Now, if you want to use fixer, try to find a local film lab that will take your "spent" fixer.

Well, no. It's illegal (in any coherent district) to put hard chemical waste (like silver) into the wastewater. you either take it to, as you suggested, a local film lab, or you clearly label it, build up several gallons of it, and take it to a chemical treatment factory, or whatever distribution process you have to get it there. Like NileRed does.

You think that’s bad? People that do wet plate collodion photography the old fashioned way use potassium cyanide as their fixer.

Allegedly sea water is a pretty good fixer too. It's not the NaCl which does it, but some other elements in the sea.

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