pb etching brass

Hello,
I have quite a problem with brass etching... Can you believe that ? I am working with Cu-Zn brass, two compositions : 41.1 and 44.1 at% Zn,
so they're alpha/beta brass. After polishing, I try to deep etch my samples using [ethanol + FeCl3], which is supposed to be the classical etchant. But most of my samples end up with a layer of what appears to be copper, or sometimes a red stuff, that masks the microstructure... I've tried to add a little water or a little benzen to pollute the solution : no difference. I tried several concentration in FeCl3 : does not work either. One suggestion would be to try to place another metal in the solution, on which Cu could agglomerate. However, my memories of inorganic chemistry are quite bad, and I don't know what metal I should use ? Anyways, any suggestion would be welcome...
Thanks a lot,
Marc
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Marc wrote:

I have always thought the FeCl3 etchant wasn't very controllable. In my metallurgy group we've had MUCH better results using: 20ml NH4OH (ammonium hydroxide) + 10 or 20ml H20 + a few drops H2O2(peroxide) It doesn't have a shelf-life, though, so you have to make it up fresh each time. We've used this on all kinds of brasses, including leaded brass.
Good luck!
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Thank you very much, Joe ! I am going to try that ASAP,
Marc
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