The authoritative public forum
  for Metal Finishing since 1989
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Trying to plate more than one metal at one time

In looking at coins that are an alloy, I am curious what will be the result of plating more than one metal at a time.  Based on the information that your website has, I am structuring some experiments to test different variables in the plating process. I want to evaluate the effect of these conditions on the final results. As a quick overview, I will be following your recommendations for simple copper plating onto a coin. We are using a 10P coin (no quarters over here)which is 75%Cu and 25% Ni.

Here is the question:

If I wanted to evaluate the results of plating Cu and Zn (attempting to get a brass-like result) with your white vinegar ⇦in bulk on eBay or Amazon [affil links] ... solution, could these two metals be plated at one time? If yes, do I need a bi-metal anode? Or, can the anode be Cu and the Zn be in solution, such as from zinc sulphate ⇦this on eBay or Amazon [affil links] ? What other solution components should/could be added, if any?

Thanks,

Roger T.
Student - eighth Grade - Farnham Royal, Slough, England
2003

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You are certainly ambitious, Roger, and that's great. But, no, there is no possibility of plating an alloy in this fashion. You may be a few years too young to even investigate it, but if you were to study the Nernst equation you could see why. Copper is so much more "noble" than zinc that it will plate out preferentially even in a solution that has ten thousand times more zinc in it than copper. To plate brass and other alloys requires special "complexers" like cyanide, which serve to tie-up the copper so some zinc can plate out.

I really don't much like these school plating experiments because there is a huge chasm between what you can demonstrate in school--plating a super thin "coloring" coating of zinc or copper out of vinegar --and anything remotely practical :-(

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

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I am very impressed by your interest and knowledge on electroplating. You have taken on a very tough project and unfortunately I too do not think you will succeed. What you want to do is very complex and needs some very nasty chemicals. However, you may like to contact the IMF (Institute of Metal Finishing); they are based in Birmingham (UK), but have branches all over the country and also have a website. They sometimes run shows for schools and this is the type of thing they may be able to demonstrate to you. If they can't, I'm sure they will be able to help you. We need more ambitious and innovative schoolchildren like yourself, so keep coming up with this type of thought!

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2003