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Electropolished Brass is turning red

2007

Hello,
I have a small Brass electropolishing process and my parts are coming out red-ish and they looks worse as soon as they get dry in the oven.

Can I solve this problem and How?

Thanks.

Rafael Perez
Consumer - Santo Domingo, Rep. Dominicana

It sounds like you have the wrong chemistry for brass. While it may have worked when it was brand new, dissolved metals can change that very fast. since you left out all of the details, people can only guess.

James Watts
- Navarre, Florida
2007

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You certainly have the wrong chemistry for electropolishing brass. The redness is due to you dissolving the zinc to leave the copper; this is a common problem with brass and is called dezincification. You should get a solution that is designed for use with brass.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2007

I used Muriatic acid (diluted HCl) to do the chemical test on red Brass (UNS 84400). The result was part turning reddish after drying at regular room condition. Your answers will be highly appreciated, and is there any other acid I can use to check the aging effect on this brass. I use the same acid for SST.

Ayaz Alware
Product Designer - La Mirada, California USA
April 24, 2009