[TheForge] Stainless contamination

[Bruce Freeman]

I can't say if this is what happened in your case, but unpassivated stainless steel DOES rust.  It won't rust AWAY, but the iron at the surface will rust.  Passivation is a treatment (usually with ~40% nitric acid, in my experience) that pickles off the iron on the surface - so it can't rust.  That leaves a nickel-chromium surface.  If the surface of the steel in question were not passivated, then you can expect rust.

Nitric acid is convenient for lab or manufacturer, but may not be handy around the shop.  It seems to me that any oxidizer (like, maybe, hydrogen peroxide) MIGHT work to passivate SS.  (This is speculation.  I have not checked oxidation potentials, etc., to see what oxidizer is strong enough.)

Bruce
NJ

>>> debmiller at fuse.net 8/23/2005 7:22:06 AM >>>
Hey Guys,

Have a question regarding stainless steel rust contamination.

I made an outdoor bar area for a client's flagstone deck. For the counter top I used a certified commercial grade stainless table and made my own legs then cut out the top for a sink. I left the protective plastic on until shortly before delivery.

Within days the client called and complained about rust. When I checked it out it looked like someone has used steel wool on it. The client says his wife didn't use anything but a sponge.

THe source of contamination is a mystery to me, but that said, any recommendation on the nest method to clean the stainless to prevent further rusting? Also how would one minimize the possibility of future contamination? Some kind of sealer?

I've never really experienced this problem before.

Ray

Ray Miller
Cincinnati

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