I have need to protect copper as well as rose gold plating from tarnish, will like to know if it is effective to chromating on top of copper, Thanks.
David Wu Jewelry manufacture - Dallas, Texas ^
Doubtful - the chromating solutions are manufactured to work with specific metals under specific conditions. To the best of my knowledge there are no formulations for copper. Also, the vast majority of chromating solutions involve hexavalent chromium - this would be a VERY BAD THING to use in the jewelry industry. Look into a clear lacquer instead.
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