Metal finishing Q&As since 1989

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How do I create a pitted and corroded finish on 420J Stainless Steel?

May 5, 2010

Hi- I was wondering if anyone has some insight as to methods and chemicals for selectively corroding 420J stainless steel.

I am attempting to duplicate a blackened, severely pitted finish in one of my weathering projects, a sword replica with a 420J stainless steel blade.

The original sword in the picture whose finish I am recreating has a 1070 carbon steel blade, which naturally made it much easier to distress in that way.

I have tried pitting my stainless blade using a 33% H2SO4 solution at room temperature left on for around 3 hours, however all this achieved was etching a few thousandths of an inch uniformly off of the blade.

I'm open to any suggestions, and I look forward to hearing from you.

Thanks so much,

James McGonigle
Hobbyist - York, Pennsylvania, United States

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Bleach tends to be fairly damaging to stainless steel. Or leave it outside at a beach or next to a swimming pool for a while.

Ray Kremer
Stellar Solutions, Inc.

McHenry, Illinois

May 11, 2010

You need to stop the mass transfer phenomena. If you embed or bury the blade in something like dirt and then add the acid, this will create scattered active points of attack instead of a uniform etch. Some aeration may also play a favorable role.

Guillermo Marrufo
Monterrey, NL, Mexico
May 12, 2010