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How to recognize passivation frosting?

Q. Can you help my understanding by some pics of accept and reject passivated steel surfaces?

Sony KNV
- Hyderabad India
April 7, 2021

⇩ Related postings, oldest first ⇩

Q. Passivation specs require the parts to show no "frosting". How can someone distinguish unacceptable surface frosting due to poor passivation from a surface given a media finish opeartion prior to passivation that leaves a matte finish another person might call "frosted"?

Fred Cone
aerospace manufacturing - West Palm Beach, Florida, USA
2004

A. "No frosting" is referring to an etching of the material, typically from contaminants in the acid -- chloride comes to mind. ferric chloride ⇦ this on eBay or Amazon [affil links] from using tap water and the dissolved iron in a well-used bath will definitely do it. Trust me, you will know it when you see it. It literally looks like frost, which is quite different from a blasted surface.

James Watts
- Navarre, Florida
2004

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