The authoritative public forum
  for Metal Finishing since 1989
  

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Black Pennies

I am nickel plating a penny for my science fair project. When I do the experiment the penny gets plated with nickel, but then it turns black. Why?

Courtney
- Carrollton, Texas
2003

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2003

Are you using a single 1-1/2 volt battery?
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

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Mr. Mooney,

Thank you for taking the time to look at my question. You asked me if I was using a 1 1/2 volt power source. I am using a regular 1 1/2 volt battery as my power source.

Thank you again! Courtney
- Carrollton, Texas
2003

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2003

A blackish color is usually what platers call "burning". It occurs when the chemistry can't keep up with the electricity being supplied. Although a part would never "burn" at 1-1/2 volts in a commercial plating tank, it can happen in a student plating project if the plating solution is so dilute or so low in metal concentration that there is not enough metal available to plate out so that the electricity is diverted into separating water into hydrogen and oxygen instead.

You said that you are nickel plating (which is not covered by our guidelines for student plating) so I guess I have to ask what solution you are trying to dissolve nickel into? If you are trying to nickel plate from a vinegar ⇦in bulk on eBay or Amazon [affil links] probably isn't strong enough to dissolve nickel. Where are you getting the nickel from?

Is there a reason you can't do the copper or zinc plating we talk about in the letters and FAQs here?

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