[Ed Seedhouse[_2_]]

On Jul 20, 6:35=A0pm, Dick Pierce wrote:
Audio Empire wrote:
The radio shack speaker cable was standard copper AFAICS,

=A0 Copper doesn't rust, but it does corrode

Actually, to be precise, the chemical process that causes
iron to rust is the same that causes copper to turn green:
the rersult is, in both cases, an oxide of the metal that's
formed the same way. Both are covered under the broad
blanket of "corrosion," of which oxidization by atmospheric
oxygen is but one type. Yes, copper doesn't "rust" because
the oxides of sopper doen't look the same as the oxides of
iron ("rust" being derived from one or another word for
"red").

Copper oxide forms on the surfaces of exposed copper but it does not
fall away and stays chemically bonded to the underlying metal,
something like a form of natural anodizing perhaps.
Many government buildings have copper roofs that turn green
eventually, and it actually, as I have been told at least, helps
protect the underlying copper by keeping oxygen away from it. One
reason why copper used to be a popular choice before it got expensive.

The "Parliament Buildings" visible from the harbor of my home town,
Victoria B.C., are a good example of this. Probably most state
capital buildings in the USA also show this. Not sure if the dome of
your federal congressional building is copper clad, but if so that
would be another example.

In the case of my bad experiences with RS cable years ago I suspect
plasticizing agents as suggested. They used to get all gummy and
unpleasant. I don't remember if the copper had changed color, but I
believe coper oxide is an insulator so that might explain it failing
as a speaker connector.

There are actually two forms of copper oxides. And as pointed out in
(as I remember it) a further post the green patina is not from the
oxide, but from the effects of sulphides on the oxide after it has
formed. It must be true because that's what Wikipedia says. :-)

Ed