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Copper turning bright cherry red?

I am doing some large sheets of copper for a client. the copper on the first sample sheets turned and nice deep brown with out much work. then I started doing the larger sheets in the same way but a different location and I got a very bright cherry red color. I used vinegar ⇦in bulk on eBay or Amazon [affil links] and salt. Any suggestion? the client wants deep rich brown.

Pepper Cald
artist - Clayton, Georgia
2005

I will bet you a Starbucks that you have a different alloy of copper or a different heat treat copper. There are frequently some differences in the same lot number, let alone different lot numbers, let alone different vendors.

James Watts
- Navarre, Florida
2005

You can use 50 gm potassium permanganate ⇦ this on eBay or Amazon [affil links] /5 gm copper sulphate/ 1 lit water solution.Only copper sulphate ⇦ this on eBay or Amazon [affil links] solution may be used too(12o gm/1 lit water, solution must be 3 days old)! Good luck!

Goran Budija
- Cerovski vrh Croatia
2005