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Stripping a steel part that has been chrome plated

I restore antique motorcycles. Lots of parts have been chrome plated over the years, but my job is to restore these parts back to their original finish which is Parkerized (manganese phosphate) I have been doing this process for many years with outstanding results. A main problem for me is I live out in the country and it is a far (50 miles one way) drive to the closest local chrome shop, to get them to strip the part down to bare steel (no chrome/copper/nickel left on the part, as none of these metals Parkerize). Most of the time when I do have them strip the parts, they do a not so careful job and there are still remains of nickel and copper that I have to blast off. I would like to know EXACTLY how to strip the old chrome parts back to bare steel. Sand blasting takes a million years and I know that chrome shops do not use the sandblasting method. Would someone mind filling me in on the exact procedure/technique? Is there a book I can purchase on this particular subject?.

Charles Hallam
antique motorcycle restorer - Wills Point, Texas, USA
May 28, 2009

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May 27, 2009

Hi, Charles. As you know "chrome plating" is not simply one layer of chrome on the steel, but a multilayer process always including nickel plating under the chrome, and often including copper plating under the nickel.

The chrome itself can be removed via a short immersion in hydrochloric acid. If you develop a good eye, you will be able to tell when the chrome is removed because it has a "blueish" cast compared to the "yellowish" cast of the underlying nickel.

Then you must remove the nickel, which is substantially thicker -- thousandths of an inch instead of millionths. There are many different possible stripping agents, but the best way to go is probably with proprietaries from companies like Metalx (Ronatec.us) [a finishing.com supporting advertiser].

Then, if there is copper, it can be removed from the steel with nitric acid, or other chemicals but, again, Metalx offers a proprietary solution.

The thing to remember is that chemical stripping can generate toxic and hazardous wastes which must be logged and manifested, and you may have to go through a permitting process in order to do these operations. Talk to your local sewer authority, who are probably the authorized agents for the EPA on this.

There are dozens of threads about stripping chrome plating on this site. Good luck.

Regards,

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