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Extracting Silver


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#1 Antonio Mendonca

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Posted 08 July 2010 - 07:14 AM

Hi Gents!

How would i go about getting most silver out of neg? Processing virgin neg gets me nothing/very little...would fogging the film entirely give me max silver? Or should i flash the neg?
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#2 Tim Gray

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Posted 08 July 2010 - 10:18 AM

I would think just throwing your negatives straight into the fixer would do it. Then extract the silver from the fixer.
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#3 Robert Houllahan

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Posted 08 July 2010 - 12:05 PM

I would think just throwing your negatives straight into the fixer would do it. Then extract the silver from the fixer.



ECN will lose all of it's silver into the bleach/fix and then you can extract with a electroplating silver collector i don't think it matters if the film is exposed or not for ecn.

-Rob-
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#4 Dominic Case

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Posted 09 July 2010 - 07:18 AM

Rob is right, assuming it's colour neg. You'll need to bleach and fix, and the silver will come out into the fixer. But if the silver level builds up in the fixer, then it won't be as effective and you may get some silver reatined in the emulsion.

Electroplating will get you pure metallic silver. Once again, if you overdo the plating current you'll get silver sulphide and other impurities that will devalue the silver.

Doesn't matter if the neg is exposed or not. You get all the silver anyway.

If it's black and white negative it is a different story. You only need fixer, but if you develop the film too, it mustn't be exposed.

When you say that processing virgin neg gets you very little silver, what do you mean? How much do you expect? how are you recovering it? how are you measuring it?
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#5 Robert Houllahan

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Posted 09 July 2010 - 08:36 AM

Hi Gents!

Processing virgin neg gets me nothing/very little



Well run several hundred thousand feet of 35mm ECN with the automatic silver collector running (we have a Degenkolb attached to our Treise ECN machine) and you will get pounds of silver a few hundred feet is not going to do it... volume volume volume...

-Rob-
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#6 Dominic Case

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Posted 11 July 2010 - 02:17 AM

My recollection might be a bit hazy, but I think you might expect to get a couple of grams of silver for every thousand feet of 35mm negative. More for some types of emulsion, less for others.
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#7 John Sprung

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Posted 14 July 2010 - 09:31 PM

Back when Laser-Pacific opened their film lab, Emory had some medallions made from the recovered silver and gave them to the customers that Christmas. They were getting enough silver back that it was a significant line item on their books.




-- J.S.
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