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

Eco-friendly Passivation on stainless steel 304 with black or white appearance

December 14, 2009

Hi,

please help me out with advice regarding Passivation on the 304 Stainless steel which shall be Eco-friendly and at the same time it should pass the H2SO4 acid resistance test for 24 Hrs. Looking to shift away from chrome process.

Thanks,

Kesava Reddy
- India

Hi, Kesava. "Eco-friendly" is a subjective and non-scientific term, but there are proprietary passivation solutions which do not use nitric acid -- and nitric acid is rather noxious stuff.

In most environments and embodiments, though, passivated 304 stainless steel will not be as attractive or rust-free as high quality chrome plating.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
December 14, 2009

---

December 30, 2009

I'm not sure if by "chrome process" you mean a nitric passivation bath with dichromate (which as an additive to a nitric bath is used with many grades of stainless, though not normally with 304) or chrome plating (which usually uses something other than stainless steel as a substrate).

However Ted is quite correct, non-hazardous alternatives are readily available for passivating all grades of stainless. Let us know if we can help.

Ray Kremer
Stellar Solutions, Inc.

McHenry, Illinois