Why did copper parts turn green?

[msmith40]

Yesterday I replated some guitar parts. They originally were gold with a layer of copper underneath. I removed the old plate, buffed everything nice & shiny, and replated with copper. They looked great, and I'd planned on applying the final layers of gold plate today.

Today those same parts have a green funk on them, which I just now cleaned off.

What happened?


Mike

[jimcarry]

Well Mike
its simple enough you just needed to apply some kind of protectent if you are going to wait to apply the second plate its quit normal for copper to turn green

[msmith40]

Its common for copper to turn green in less than 24 hours.......??

I've got a jar full of pennies that still look like pennies.
What am I missing here?


Thanks!

[jimcarry]

Originally Posted by msmith40

Its common for copper to turn green in less than 24 hours.......??

I've got a jar full of pennies that still look like pennies.
What am I missing here?


Thanks!

Yes
What you have to remember is that a pennies are a solid copper piece not just a thin plate
but even a penni will turn green if left in the wrong environment

[msmith40]

After I applied the copper-plate, I stored the items in a sealed tupperware container. Would the fact that the items were in contact with each other be a factor? (Hmmmmmm. Let me guess that the answer will be......."Yes.")

So, in the future, I should immediately plate the gold over the copper?


Thanks!
Mike

[eprigge]

The green is (probably) copper hydroxide, so it would form when the copper is wet and more rapidly if it still had some chemical residue on it to promote oxidation. If you rinse very well and dry the parts, you won't see that. Being sealed in tupperware might have trapped whatever moisture you had on them.