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Stripping Nickel and Gold from Type 303 Stainless

Q. We recently stripped a nickel/gold finish from an SS303 base using a nitric acid solution. The result was a heavily etched SS303. We routinely use nitric to strip various SS bases without etching, but this 303 behaved differently. Is there something unique about SS303, as compared to other SS, with respect to stripping?

Craig Ingalls
plating shop employee - Anoka, Minnesota, USA
September 20, 2012

A. 303 has enough chrome in it I would expect it to be inert in nitric strip.

I suspect you may have had an accidental galvanic cell in your strip tank. If there were parts that stripped sooner than others hanging on the same metal bar in electrical contact, then the stainless areas may have became anodic relative to the more noble gold/nickel parts.

We wrap our nitric strip bus bars with plater's vinyl tape to prevent that from happening to us again.

Art Cambell
- OKC, Oklahoma
October 11, 2012

A. Was it 303L? are you sure there is NO chloride in the nitric acid.

Russell Richter
- Danbury, Connecticut, USA
October 25, 2012

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