Conservation Question

I'll need to ask. Usually unsightly toning (tarnish), PVC, dirt, haze, and crud. Also to brighten-up a dull surface.

 

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The only way to keep the copper from continuing to do this is to remove it. Nitric acid would work best. I worked on some gold coins that actually had the same issue with some silver flakes that came out of the press and got on some gold. They turned black, and it made the buyer suspicious that the .9999 fine gold he was buying was just plated. The nitric took care of the problem permanently. The problem with alloyed gold is that using any chemical cleaner will change the color of the coin, since you will be removing metals. That's why the St. Gaudens shown on the NCS site looks brassy.

 

@TheFinn, do you have before and after photos by any chance?

Steve

 

I don't. They weren't my medals. I am a chemist, and I suggested to the owners to treat them with nitric rather than reprocess the pieces. Out of 29 pcs only three didn't come out. They were even prooflikes, so it was pretty successful.