[Boatanchors] Rust, Coatings, etc.

[Al Parker]

Hi Mick, et al,
	"Back then", in the 1960's I think, US Steel came out with an allow 
they called "Corten" I think, which automajically did that sort of 
thing.  Looks pretty bad for the first cupla yrs, supposedly would end 
up with a fairly even brownish coating of rust.  I vaguely remember 
seeing it done on one building in the Pittsburgh, PA area, where US 
Steel is headquartered.  I was an engineer there in the Alcoa 
headquarters.  IIRC, reading trade mags, they gave it up, partly because 
strangely enough a building under construction, or shortly after, would 
have very pronounced corroded streaks down the sides from upper stories, 
that never evened out.  They figured it was because of the lack of 
portapotties for construction workers, who just relieved themselves 
"over the rail."
73,

Al, W8UT
www.boatanchors.org
www.hammarlund.info

"There is nothing -- absolutely nothing -- half so much
worth doing as simply messing about in boats"
Ratty, to Mole

On 4/7/2013 10:38 PM, Michael D. Harmon wrote:
> I've been reading the thread about rust converting coatings, and I
> remembered something from about 35+ years ago that I've always wondered
> about.
>
> Westinghouse built a factory back in the Seventies in Jefferson City, MO
> when I lived there (later bought by ABB).  They manufactured big
> industrial transformers and switchgear, as I recall.
>
> Once they had the exterior of the building completed, they treated it
> with something that made it rust.  Yes, that's right - as in the
> reddish-brown iron oxide.  As first it looked pretty bad but after a
> while it settled into a deep red-brown color and actually looked sort of
> unobtrusive.  Not what you'd expect from a big steel building covering
> several acres.  I asked someone why they did that and was told that the
> rust was only surface deep and permanently protected the underlying
> steel from further corrosion.
>
> I'm wondering if any of you have ever heard of a similar situation where
> rust was used as a protective coating?  Does the process have a name?
> Does it work somewhat like gun blue?  Gun blue uses phosphoric acid and
> creates a deep blackish-blue protective coating (iron phosphate?), but
> can rust if you leave salty fingerprints on the surface and don't keep
> the surface protected with a light film of oil.  You don't find many
> shops that do hot-dip bluing any more, because the salts and solutions
> (and fumes) used in the process are pretty noxious.
>
> Mike, WB0LDJ
> mharmon at att dot net
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