Metal finishing Q&As since 1989

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Valencies effect on electroplating quality

2002

I am completing an assessment for science regarding electroplating. I am attempting to electroplate four brass keys with other metals. I was wondering if the quality of the job has a relationship with the valency of the element.

Please explain,

Jaime Auton
- Sydney, New South Wales, Australia

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Your question is a little bit vague, Jamie. Offhand I know that electroplating is successfully done out of salts where the metal has a valence of +1, +2, +3, +4, and +6. I'd have to think about a while in order to say whether electroplating is conducted where the metal valence is +5 or +7.

But certainly the quality of the job has a relationship with the valence in many ways. For example, you can't successfully plate +2 tin out of a stannate bath where the valence is supposed to be +4; you can't successfully plate out the +3 chromium that is a contaminant in a standard +6 chromium bath. Further, you can't successfully plate noble metals out of simple salts onto baser metals (for example you won't successfully plate copper onto steel out of a copper sulphate [on eBay or Amazon]bath where the copper is +2); rather, you need to plate it out of a cyanide bath (copper valence +1) or pyrophosphate bath where it is complexed.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2002