Copper flash after neutralizing on sterling silver

Chemistry
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I'm a jeweler.  I'm using Argentium silver with germanium.  I pickle in a solution that contains sodium bisulfate combined with distilled water.  All okay after that...the problem is when I neutralize the pickle in distilled water & baking soda, or even distilled water and a mild dish detergent, I get a slight copper flash...No body's been able to explain why this is happening...so I thought a chemist would know..Thanks..

Jun 12th, 2015

Thank you for the opportunity to help you with your question!

 sodium bisulfate -- for pickling with copper alloys or if you are in a group-studio situation. I have one pickle pot that I use for all metals, and I haven't had any trouble. However, it's not a bad idea to avoid any cross-contamination; it's possible that contamination in the form of copper deposited on the surface of the Argentium sterling could affect tarnish resistance.

Please let me know if you need any clarification. I'm always happy to answer your questions.
Jun 12th, 2015

Thank you for your answer.  The metal is perfectly clean when it comes out of the pickle pot...my problem is when I put the pieces in a neutralizing bath, either baking soda and distilled water or mild dish detergent and distilled water...heat or no heat.  I keep getting the same weird chemical reaction on many pieces...some pieces are okay.  Every time I take a piece that's been in a pickle bath and neutralize it with anything even slightly alkaline...I get this weird coppery thing on some of the surfaces of the castings.  I'm not worried about the tarnish resistance, because after you finish working on a piece, the last thing you do is heat it in an oven at 250 for about 20 minutes and that's supposed to revive the germanium layer...and thus the tarnish resistance.

Jun 12th, 2015

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Jun 12th, 2015
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Jun 12th, 2015
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