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

The process by which pennies get their copper coating

I am a grade twelve student. In my chemistry class, I am required to complete a research paper regarding the applications of electrochemistry to the process by which pennies (post-1982) get their copper coating. Do you know the commercial means (not a classroom or small-scale experiment, but for the purpose of public use) by which this is done? Is the zinc disc submerged in a certain electrolyte containing copper ions? Does the process require the use of a voltaic cell to force reaction? Thank you for your time. Any help will be greatly appreciated.

Jaime B.
student - Edmonton, AB, Canada
2003

---

Yes and yes. The zinc blanks are electroplated in a copper plating bath in plating barrels. See "An Introduction to Barrel Plating" by Frank Zemo for some text and pictures which clarify what barrel plating is about. Please do not ask Mr. Zemo any follow-up questions; instead post them here. If you are ambitious, get a copy of "US Mint Claims Copper Plated Coin Makes Economic Sense" from Plating & Surface Finishing magazine, July 1981.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003

I am a senior and am need to find out how to copper plate a coin or key. I don't know why if you have the copper strip why the blue copper stones?

Jamie C.
- Willow Springs, Missouri USA
2005

---

If you are thinking of plating the key just for educational reasons, please see www.finishing.com/faqs/school.shtml as a start, Jamie. You don't need the blue stones, but you do need to create a blue solution because if the solution is not blue, it has no copper in it, and if it has no copper in it, you can't plate copper out of it.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2005