Metal finishing Q&As since 1989

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Brass plated guitar parts are wrong color

Dear Sir:

I had some parts for my guitar brass plated. The pickguard on the front of the guitar is solid brass, and I wanted the bridge, tone knobs and knob plate plated to match, or come as close as possible to matching, the solid brass pickguard.

When I picked up the parts, they all had a "copper" cast to them. They even plated the pickguard (all I had asked them to do to that was clean, polish and buff it). They said they plated the pickguard so all the parts would match. I told them the parts match but they aren't yellow brass, which was what I ordered and expected.

Their response was that at this time of year, when the temperatures are high (I live in Phoenix) and the humidity is high (we're in our monsoon season), brass plating doesn't come out yellow, it only comes out yellow in the winter when it is dry and cool.

My question is, does temperature and humidity make a difference in the way the color of plating turns out, or is it the mix of chemicals?

Thank you,

Henry Thome
- Phoenix, Arizona, USA
2001

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2001

If the color is not right it's not right, regardless of why. It should be close to what you want, although I think I'd agree that to expect it to match cast brass would be unrealistic, so it was a good idea to plate the pickguard.

I am not aware of humidity being a particular problem, but it is true that it is difficult to hold the color in an alloy plating like brass because a minute change in the percent of each metal in the alloy can change the color noticeably, and there is much much more to depositing an alloy of a given composition than just "the mix of chemicals"--also involved are temperature of the bath, agitation, current density, etc. Perhaps their brass plating bath has neither heating nor cooling so the color depends a bit on the ambient temperature that week :-)

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