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  for Metal Finishing since 1989
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Demonstration How to Plate a Copper Penny with Zinc

I was reading your demonstration on how to plate a copper penny with zinc and I thought it would be a great demonstration for a science class (I volunteer at a local Junior High.) One question I have--you mention that you should add 100g/l of epsom salt [affil links]s and 120 g/l of table sugar to the solution. I assume the epsom salts is to increase conductivity, but I'm not sure I understand what the table sugar is for.

Thanks,

Andrew Neice [last name deleted for privacy by Editor]
- New Haven, Connecticut, USA
2001

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2007

The idea behind the sugar is for it to function as a "brightener". This is an organic addition agent that co-deposits with the metal and, by so doing, prevents the growth of large crystals of zinc. In actual industrial electroplating, proprietary brighteners are used and they are very important towards brightening the finish, decreasing porosity, and hardening the deposit.

Whether the sugar is really functional on the very thin deposits achievable from a vinegar ⇦in bulk on eBay or Amazon [affil links] solution is debatable -- but that's the idea behind it at least :-)

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