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Staining of 303 stainless steel

On etching 303 stainless there sometimes is a discoloration. What is this and how can I correct or prevent it?

William Fetish
a rubber to metal specialist - East Rutherford, New Jersey, USA
2003

This is probably the sulfur coming out of the 303 stainless steel. This is a common problem and can be prevented or corrected by soaking the parts in a high alkaline solution. Some formulations on the market allow less time and lower temperature than others, but even straight 10% NaOH will work if you leave it for an hour or two at 160-180 °F, depending on how bad the sulfur is. Some lots are little problem, some are a great problem.

Lee Kremer
Stellar Solutions, Inc.

McHenry, Illinois

2003

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