# Silver-containing fixer



## MysticColby (Nov 15, 2012)

So, I just found out my work uses silver halide films.

I've started collecting the developed films we would otherwise throw away (soak in dilute NaOH and the silver oxide settles to the bottom of the container). The undeveloped films are a metallic bronze color, the developed films are a dim transparent blue color, the post-soaked films are a clear pale blue color.
The films definitely drop black powder when soaked in NaOH after a few hours (I haven't converted to metal and melted yet).

But I also wanted to look into recovering silver from the fixer.
I collected a sample of it, and it's bright yellow (is that normal?).
From what I've read, you can add NaOH to precipitate silver oxide.
But when I added NaOH, it just got more yellow with no precipitate. (I tried several different amounts of NaOH and diluting with water, none worked)
I even tried adding lactose with NaOH (lactose is supposed to be a reducing sugar, and we had it on hand, so I used that) but no precipitate.
What's wrong?
Am I trying to reclaim it incorrectly?
I'm wondering if the developer machine has a reclaimer for the silver built into it, or possibly some sort of inhibitor to prevent people other than the company we buy the fixer from from reclaiming the silver (I'm sure they make a hidden profit by picking up our waste, which they do do).

Thanks for the help


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## Westerngs (Nov 15, 2012)

The fixer may not have any appreciable amount of silver in it.

One way to find out is to take a new penny, very bright finish, or a very clean piece of copper strip, and dip it in the untreated fixer for about 30 seconds. If there is silver in it, it will cement out on the copper. Look for a dark to gray coating on the penny or copper.

If there is very little or no silver (less than about 5-10 ppm), the penny will be shiny.


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## MysticColby (Nov 16, 2012)

I was expecting a big black cloud of silver oxide 
Well, I took a 50 ml sample and dropped a bright shiny new 2012 penny (mostly zinc, little copper) in it. nothing happened after 2 minutes. I'll leave it in there and check again on monday.


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## MysticColby (Nov 19, 2012)

Well, something happened. after leaving a penny in some fixer waste over the weekend:
the solution turned green, the penny turned dark (it's more of a dark film that flakes off, kinda a brown color), and there are flakes that settle. some of the flakes look black, others look white/grey. out of the 50 ml solution, there's maybe 0.01 ml of flakes (not measured, just estimated to give you an idea of how much)


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## goldsilverpro (Nov 19, 2012)

http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=50&t=3558&hilit=fixer+copper
http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=53&t=6806&p=60953&hilit=copper+fixer+test#p60953

These give a valid method for testing silver in fixer. Manuel gives the concentration based on how long it takes to silver the copper. In my experience, the info is reliable. I always used solid copper wire and cleaned it well by scraping it with a knife or sanding it right before using it.

Like Manuel says, the silver coating is either gray or shiny silver. Black is not silver. It is probably copper sulfide from some decomposition of the thiosulfate. If there is silver there, I would think you would see it within about 10-20 seconds at the most. From what you've said, there is no silver in your fixer.

__________________________

By the way, has anyone heard from Manuel? Been a long time. He was one of my favorite people on the forum. I miss him.


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## MysticColby (Nov 20, 2012)

Thanks for the help, guess I'll just have the films
one last thought: would the silver in spent fixer settle to the bottom? it's a pretty big container (about 50L), too heavy for me to lift alone and pour, so I had to take all these samples from the top.


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## joem (Nov 22, 2012)

MysticColby said:


> Thanks for the help, guess I'll just have the films
> one last thought: would the silver in spent fixer settle to the bottom? it's a pretty big container (about 50L), too heavy for me to lift alone and pour, so I had to take all these samples from the top.


No, any residue most likely would be oxidized fix. Also for the above, if your film is exposed to light the silver will not transfer into the fix. I have done iron replacement and came out with an iron contaminated powder.


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