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Stainless surface corrosion
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Cliff Smith
(cliffsmith) - F
Stainless surface corrosion on 04/14/2012 09:41:31 MDT Print View

This is about undoing a materials selection mistake I made (using brushed instead of polished stainless).

My 304 stainless tubing is getting ugly surface corrosion because it lives in a marine environment. (Yeah I shoulda used CF or polished stainless.) I'd like to clean up the stainless well enough to paint over it. So, 2 questions:
1. How do I prep the surface to accept paint?
2. What kind of paint should I use? (2-part epoxy?)

Thank you

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Stainless surface corrosion on 04/15/2012 00:34:22 MDT Print View

(I looked just out of interest)
A. Generally speaking, an epoxy paint would be an excellent choice for painting Type 304 stainless steel. This statement applies to 100% solids, high- solids, low-solids and powder coatings. An epoxy primer would certainly be suitable for this application.

It would be wise to abrade the surface using something that does not cause iron particles to become embedded in it. Blast cleaning is an excellent method. In any event, the surface abrasion should be light.

A potential alternative to surface abrasion is a phosphoric acid-activated vinyl wash primer applied to a degreased surface and then top-coated with a liquid epoxy. This would be an excellent finish system for Type 304 stainless.

Solvent cleaning, if properly done, can also be used. The problem with solvent cleaning is potentially leaving diluted oily residue on the part surface. For this reason, if you choose this method of surface preparation be sure to change solvents often and, if you are wiping, change wipers often. I still prefer surface abrading.

warren mcclintock
(the_gr8t_waldo) - F
all metals except gold,platinum,palladum corrode spontaneously on 04/15/2012 10:44:30 MDT Print View

is this "marine enviroment" in the water or in the air?. if in the water then i wouldn't paint or otherwise coat it. this will lead to "crevice corrosion". if in the air i would inspect the fastners to make sure that dissimilar metals were not connected to it causing "galvanic corrosion" if youre corrosion appers to be small rust spots, it's probably steel fragments embedded in the stainles from the forming and installing the gear. to my limited understanding the cure is cleaning , often and plenty of fresh water. sorry but i'm unable to poast links, but there's a lot about stainless and corrosion, on the web. i don't think that these days you'll find anyone who'll "passivatate" a chemical cleaning process

Edited by the_gr8t_waldo on 04/15/2012 10:47:55 MDT.