The authoritative public forum
  for Metal Finishing since 1989
-----

Polishing the steel after passivation

I do passivation to my stainless steel products. after the passivation process I refinish them for shine and stuff. is that effect the protective layer on the steel or re polishing make the surface active again. I have to refinish ( polish) the surface again to removes the water stains. Also I use DI water with 20% nitric acid, do you think its a right solution for passivation. I use another method, boiling the steel instrument for 20 min in salt water and leave it as it for 12 hours ( surface get rest) then rinse with DI water and make a solution of citric acid powder with DI water ( 2 table spoon of citric acid powder per 1 liter water) and boil the instrument for 20 min and rinse it and dry ( rust removes and surface is clean), please advise me if this method is fine too? Thanks

Asif Bunce
Surgical Instrument manufacturer - Pakistan
November 28, 2009

---

To remove water stains and to achieve some polish, I suggest you try using mass finishing equipment and a treated dry organic media. It is time comsuming but no labor required.

AF Kenton
retired business owner - Hatboro, Pennsylvania
December 4, 2009

---

Asif,
Passivation should be the last process performed. When you say polish, do you mean coating the parts with a "polish" product, or abrading the parts to create a smoother surface? If the former, that's fine, do that after passivation. If the latter, no, finish doing that before passivating.

Water stains can be avoided by using purified water (DI, etc.) as your final rinse. You shouldn't have to polish a part to remove water stains, anyway.

Ray Kremer
Stellar Solutions, Inc.

McHenry, Illinois

December 7, 2009