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  1. #21
    Michel Hardy-Vallée's Avatar
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    Quote Originally Posted by Donald Qualls
    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.

    (...)

    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.
    Donald, what do you suggest for the non-DIY among us to do with the sludge of impure silver? Should it just go down the drain again, or must it go to the hazardous waste disposal facilities?
    Using film since before it was hip.


    "One of the most singular characters of the hyposulphites, is the property their solutions possess of dissolving muriate of silver and retaining it in considerable quantity in permanent solution" — Sir John Frederick William Herschel, "On the Hyposulphurous Acid and its Compounds." The Edinburgh Philosophical Journal, Vol. 1 (8 Jan. 1819): 8-29. p. 11

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  2. #22
    Donald Qualls's Avatar
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    Quote Originally Posted by mhv
    Donald, what do you suggest for the non-DIY among us to do with the sludge of impure silver? Should it just go down the drain again, or must it go to the hazardous waste disposal facilities?
    First suggestion would be to contact a local mini-lab processor and ask them if they could add your silver to their recovered silver, which is picked up for them (often for free, the disposal paid for by the silver metal reclaimed).

    To elaborate, mini-labs generally run an in-line silver recovery unit to extend fixer life and comply with environmental requirements; this unit produces silver sludge similar to that you'll find in your fixer bucket after steel wool treatment. Since silver is considered a "toxic heavy metal" (for waste disposal purposes -- doesn't mean silver jewelry is dangerous, or even silver eating utensils, though using *nothing* but silver to eat from can lead to argyria, the source of the "blue blood" expression for the very rich or royalty), it can't be disposed of down sewers or in common trash (at least by businesses, who typically produce hundreds of times as much as home processing would). So, the silver sludge is "disposed of" by "helpful" souls who take it away and, usually, smelt it into purer form and sell the resulting ingots -- potentially back to companies that process the silver into film, but there are many industrial uses for silver. These folks make enough selling the silver that they frequently don't charge for their service of removing the toxic waste -- and as a result, many mini-labs will be happy to add your silver sludge to theirs for disposal.
    Photography has always fascinated me -- as a child, simply for the magic of capturing an image onto glossy paper with a little box, but as an adult because of the unique juxtaposition of science and art -- the physics of optics, the mechanics of the camera, the chemistry of film and developer, alongside the art in seeing, composing, exposing, processing and printing.

  3. #23
    Bob F.'s Avatar
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    From reading, it is my understanding that the major problem with spent fixer is the silver: it is poisonous to the microorganisms that process our sewage. Once the silver is removed, it is relatively harmless to dispose of and can be used as a dilute plant feed as Donald suggests.

    Feelings of guilt can be assuaged by asking your local water company how many millions of gallons of water is lost through damaged and badly maintained supply pipes in an average year. Add that to the amount of water wasted in industrial processes and although it may not entirely render you guilt-free, it will put your personal water use into perspective...

    Cheers, Bob.

  4. #24

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    Somewhere around here I have plans for a small silver reclamation unit scaled for a small darkroom that works a lot like the large rotary units we have at work.

    It is a simple affair with flexible metal plates that you put the fix into and turn on the current. Minutes to an hour later, you remove the fix and find pure silver plated to the anodes, which can be recovered by flexing the metal plates and gathering up the flake silver.

    The only possible problem is if you pass too high a current, you liberate sulfur compounds and ruin the fix.

    I can have a look around if anyone is interested in the plans.

    Frank

  5. #25
    david b's Avatar
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    The computer company "Intel" is in Rio Rancho NM, which is about 20 miles outside of Albuquerque. I heard they use 1 million gallons of water per day to make computer chips. When asked to cut back, they stopped watering their corportate lawn.

  6. #26

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    Quote Originally Posted by Donald Qualls
    First suggestion would be to contact a local mini-lab processor and ask them if they could add your silver to their recovered silver, which is picked up for them (often for free, the disposal paid for by the silver metal reclaimed).

    If you are going to go this route though, it makes more sense just to haul your spent fix to them and let them extract the silver themself. Many labs will do that for free, and then you are rid of the whole mess without the work.

  7. #27
    joeyk49's Avatar
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    Kino:

    I'm interested. Let me know what you find.

    Very interesting topic...I learned a buch, thanks guys!


    Joe

  8. #28
    Donald Qualls's Avatar
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    Quote Originally Posted by Kino
    Somewhere around here I have plans for a small silver reclamation unit scaled for a small darkroom that works a lot like the large rotary units we have at work.

    It is a simple affair with flexible metal plates that you put the fix into and turn on the current. Minutes to an hour later, you remove the fix and find pure silver plated to the anodes, which can be recovered by flexing the metal plates and gathering up the flake silver.

    The only possible problem is if you pass too high a current, you liberate sulfur compounds and ruin the fix.

    I can have a look around if anyone is interested in the plans.

    Frank

    I'd be interested in this -- if it's simple enough to run off a small (cheap) battery charger or similar, I'd probably start recovering my silver instead of one-shotting my fixer as I've been doing.

    Of course, even removing the silver doesn't extend fixer life indefinitely; especially if you process T-Max or similar films, iodide buildup will reduce the effectiveness of your fixer about as fast as silver capacity is used up (which is why fixing T-max films reduces the fixer capacity -- no more silver, but lots more iodide compared to conventional films). But I wouldn't mind having a ready source of flake silver; in that form, it'd be pure enough to save up, then get some nitric acid and make my own silver nitrate solution for van Dykes or salt prints.

    I think you already have my e-mail address...
    Photography has always fascinated me -- as a child, simply for the magic of capturing an image onto glossy paper with a little box, but as an adult because of the unique juxtaposition of science and art -- the physics of optics, the mechanics of the camera, the chemistry of film and developer, alongside the art in seeing, composing, exposing, processing and printing.

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