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Ted Mooney, P.E. RET
Pine Beach, NJ

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Passivation for stainless steel ASTM 313 grade 302 springs.

July 7, 2009

I have to passivate 25 stainless steel ASTM 313 grade 302 springs.

What chemical do I have to get to reach the right passivation process?

Thank you,

Amber DePaul
hobbyist - Muncie, IN, USA

Hi, Amber. You may or may not realize it, but there are jobshops who can perform this service for you so that you have no need to deal with regulated, toxic chemicals. But if you wish to do it yourself, the two approaches are nitric acid or proprietary citric acid processes. The citric acid is far safer, but either approach is only applicable to clean parts (waterbreak-free). I don't think you can get the parts clean enough by simple immersion in consumer-safe chemicals, so you will need to scrub them with pumice ⇦this on eBay or Amazon [affil links] and a tampico brush. Good luck.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
July 8, 2009

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