The authoritative public forum
  for Metal Finishing since 1989
-----

Brilliant copper finish

In Michigan's Upper Peninsula, you can pick raw copper from mine tailings, and find lovely specimens. The natives sell these, cleaned and processed to brilliance, on the roadsides. But no one will tell you how to achieve this *better than a new penny* finish on your own findings. They are not lacquered, as over time, they will dull down. Would you have some insight to this finish?

Barry Pelham
hobbyist - Mattoon, Illinois, USA
March 11, 2010

---

March 18, 2010

Barry,
There are many ways to brighten copper chemically. If copper is polished correctly, it will also have a very shiny finish. If the copper tarnishes over time there is nothing special with the "finish".

Mark Baker
process engineer - Malone, New York

Mark, thanks for looking at my inquiry. Could you give me a suggestion from the many ways? Polishing is out of the question, due to irregularity of the surface. I would have to come up with chemicals on the Internet, and would hope to keep them *non prescription* varieties if possible. I have tried Copper Brite, which removes darkness, but has no brilliance. thanks.

Barry Pelham
- Mattoon, Illinois, USA
April 5, 2010

---

April 7, 2010

Barry,
Because the shape of the copper is irregular, and you are asking for a non prescription formula, try 1 gram table salt in a bowl. Add just enough vinegar ⇦in bulk on eBay or Amazon [affil links] to moisten all the salt to a paste. Use a medium (hardness) toothbrush to apply the mixture and scrub. If the copper pieces are small you could hold them with tweezers while scrubbing. Rinse with water with a little bit of lemon squeeze and dry with a clean soft cloth. Another OTC method is to use ketchup.

Mark Baker
process engineer - Malone, New York

---

bingo! got what I need from a comment by Ted Mooney on another question: look for old patents. This one is current, but the acid/peroxide part is free info. Thanks to all.

www.freepatentsonline.com/5630950.html

Barry Pelham
- Mattoon, Illinois, USA
April 7, 2010

---

Hi, Barry. This sulfuric-peroxide process is very widely used in the plating and metal finishing industry. Probably the biggest issue is that the peroxide dissipates unaffordably rapidly unless the process includes proprietary stabilizers. You can ask the site's supporting advertiser EPI / Electrochemical Products Inc. [a finishing.com supporting advertiser] for "sulfuric-peroxide bright dip for copper" and they'll know what you are talking about and be able to supply you with the stabilizer. If you must stay non-proprietary, I believe that the process will work without the additive; maybe you can mix just enough each time you want to use it. Good luck.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
April 7, 2010

Again, thanks to Ted and Mark. Looks like the first and easiest will be salt and vinegar, and if I'm not bright enough, will work with the peroxide formula. Ketchup? Of all things; might try it for grins.

Barry Pelham
- Mattoon, Illinois, USA
April 12, 2010