Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
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Anodizing of brass
Q. What is the quickest/easiest way to anodize brass?
Maybe I am using the wrong word. I live in a very old house. All of the door hardware is original except one door. I bought a new brass doorknob and I want it look old and tarnished like the rest. It is much too time consuming to polish all of the old hardware. I am looking for a way to get the patina look on the new knob.
Thanks,
Lori D [last name deleted for privacy by Editor]- Minneapolis, Minnesota, USA
A. Well you know I'm pretty confused here. Is the issue anodizing of brass or anodizing of titanium?
Titanium can be anodized with a thin light-defracting coating for jewelry use or with a heavy coating for anti-gall applications. But when titanium racks are used in aluminum anodizing solution, the intention is not to anodize the racks, that's just a consequence of its use. The solution used, 10 percent sulfuric acid, generates a very thin anodization layer on the titanium, thin enough that it is still conductive enough to use for a rack.
Brass is an alloy of copper and zinc. Copper cannot be usefully anodized. Zinc can be anodized but only at very high voltages (hundreds of volts). My understanding is that brass cannot be anodized. Letter 1785 alludes to an historical oxidized finish for brass without making any claim, though, that electricity has anything to do with it.
This letter probably came after you finished your project, and I hope it has turned out the way you wanted it to be.
Regards,
- Minneapolis, Minnesota,USA
October 22, 2014
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