On Thu, 6 Nov 2008 11:12:09 -0500, "Ed Huntress"
wrote:


"Dan " Dan@ wrote in message ...
Is this the same steel they use to build bridge beams out of? I was
somewhere that had the bridge beams rusted purposely so they don't
have to paint them. It was either Duluth, or San Diego. How's that for
getting old? Can't remember where.

Yeah, that's the kind of application that Cor-Ten was made for. It came out
in the late '70s, IIRC, when I was covering materials for _American
Machinist_, and it was being promoted for all sorts of structural and
decorative uses.
The company I worked for, used it for pier nosings on a bridge in
Jamaica around 1967.

Here in NJ they used it for guard rails on the lower end of
the Garden State Parkway. Like most applications, it looked like hell for a
few years and then it turned a nice, rich brown. It looks pretty good, and
it saves a lot of maintenance cost -- which is the whole point of it.

Because the rust has to form a dense and nearly impermeable structure, it
matters how the rust is formed, and I think it matters how fast it's formed.
That's why I'm skeptical that you can speed up the process. But maybe
they've come up with a chemical treatment for it since those days. I haven't
followed it.
Gerry :-)}
London, Canada