Metal finishing Q&As since 1989
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How to strip hard chrome at home
adv.
Q. Having a hard time stripping hard chrome off some brake caliper pistons. Original chrome is peeling and badly pitted.
Tried HCl and didn't touch the chrome (but turned exposed base steel black). Then tried NaOH, sitting for 3 days with zero effect.
I'm ready to try anodic cleaning in NaOH but not sure what to do with the hexavalent chromium.
- Bloomington Indiana
October 8, 2023
A. Hi Andy. Not that I'm encouraging you to strip chrome yourself (I'm not), but chrome quickly dissolves in HCl, How do you know it's chrome?
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
It's a piston from a brake caliper. These are normally zinc, however one caliper looks like it was rebuilt before and looks like a thick layer of hard chrome. This is partially corroded where the seal was, as it sat for several decades.
I'm assuming it's hard chrome, as I can't really think of what else it could be.
The pistons in the other calipers were zinc and dissolved easily in 35% HCl. But the HCl would not touch the hard chrome.
- Bloomington Indiana
October 17, 2023
A. Hi again. If it doesn't dissolve in HCl it's not chrome. I guess I would suspect that it's either nickel plating or electroless nickel plating.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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