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Obtaining flame colors on copper

I am torch cutting .040 thick copper, resulting in, a black red oxide coating. I can clean this back to original copper color with a solution of vinegar ⇦ in bulk on eBay or Amazon [affil link] and salt. My question is how can I obtain rainbow type colors on clean copper. I have read about controlled heat method but don't know what temp.and time is required. I have tried flame torching with little success. The result being very little color variation.

Thanks for your help.

Sam Gonnella
hobbyist - Pueblo, Colorado, U.S.A
2004

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Ref a book dissolve 4g caustic +fine sugar 4g in 100g water.boil for 15 minutes, and while stirring add ,slowly, 4g copper sulphate ⇦ on eBay or Amazon [affil link] solution. Immersing in hot solution will create coloring rainbow from gold to green to black.

Khair Shishani
aircraft maintenance - Al Ain, UAE
2004

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October , 2008

Hi, Sam. Several examples are shown and a good discussion of the subject is available on letter 2662. Good luck with it!

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Need quick confidential answers? $25
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