On Fri, 12 Mar 2010 11:41:25 -0700, "chaniarts"
wrote:

wrote:
On Thu, 11 Mar 2010 23:27:52 GMT, (Doug Miller)
wrote:

In article , "chaniarts"
wrote:
Doug Miller wrote:
In article
,
harry wrote:

The only benifit of cast iron is it doesn't rust much.

As compared to copper or aluminum, which ... don't rust at all,
actually.

huh? rust is the metal changing into an oxide. both copper and
aluminium rust, forming copper oxide (green) and aluminim oxide
(white). they just don't rust orange like iron does.

Wrong. Rust is, by definition, hydrated iron oxide. Copper and
aluminum *oxidize*, but only iron can rust.

Oxides of copper and aluminum are not porous, either (oxidation stops
quickly). Rust is.

really? aluminim oxide can be formed as a powder, which is pretty porous.

Really. Aluminum oxide is impervious to oxygen. Aluminum will only oxidize
on the surface. Scratch a hunk of aluminum and it'll get shiny, for a couple
of minutes.

never had a pinhole in copper pipe show green, and still leak?

I had a nail hole turn green and leak. The nail was on the inside. :-(