Metal finishing Q&As since 1989

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Removal of discoloration on stainless steel caused by plasma cutting

I cut stainless steel with a plasma cutter resulting in some burned edges which resembled rings of oil on water. How can this be removed without changing the surface of the stainless steel.

Sherman C. Ward Jr.
Artist/Sculptor - Haddonfield, New Jersey
2006

Where can I find any responses to my question?

Sherman C. Ward Jr.
N/A - Haddonfield, New Jersey
2006

Ed. note: Hello, Sherman. Sorry for any misunderstanding. This is a monitored public forum. If anyone replies to your question, their reply will be posted right here.

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2006
muriatic acid [affil links]would be the conventional way to remove heat scale. However this will slightly dull the overall finish and require thorough rinsing and neutralizing with a dilute caustic soda [affil links] immediately after applying and then a thorough water rinse. After that restoring the original finish would require some type of mechanical finishing process.

I'm sorry this is not the answer you are looking. Very rarely will you find an easy one step process to metal finishing.
Good luck Frank

Frank DeGuire
- St. Louis, Missouri, USA

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Try this. Use a 12 volt battery charger [on eBay or Amazon] with the positive lead hooked to the work. The negative lead goes to a 12 volt light bulb (automotive turn signal works) then to a stainless wand (a piece of scrap 1/16" by 1/4" by 7"). Wrap the end of the wand with 2 layers of thin felt for about 1.5 inches and secure with wire (the kind used to close a loaf of bread will work). Dip felt into phosphoric acid rust remover (inexpensive at auto parts store) and rub area to be cleaned. Bulb should light during process. Brown discoloration will go away. rinse well with hot water when done. This works on 300 series stainless steels. Process does not seem to etch the work piece. Refinement of process will be required but this should prove to be an inexpensive way to try it out.

Paul Dadd
- Willoughby, Ohio
February 26, 2010