On Fri, 17 Apr 2009 15:18:30 +0100, "Steve Terry"
wrote:

but oxidises easily so silver should be covered, PTFE is one of the best
coverings.


Silver oxide is acceptable. It remains as a mechanical part of the
surface, and does not adversely affect conductivity.

Copper oxide is an unacceptable CRUST on your wire.

That is one reason why Sivler was used to plate copper wires.