Allan,

Here's my take on the wire thing.

People above have hit on the tarnishing thing. Wire that use in electric cords and that sort of thing may oxidize and turn a dull color. A lot of this wire may be made with Oxygen-Free Copper. When they manufacture the cord, they extrude the copper and clad it with the cord's insulation at the same time. This keeps air out of it and keeps the copper wire from oxidizing inside the cord. When you strip the wire cord insulation off, you have shiny, new looking copper strands. They will oxidize over time.

Wire made for fly tying is coated to keep from tarnishing. I have no idea what they coat it with.

Copper wire from motors, coils, solenoids and that sort of thing have been treated with an insulating varnish. Any electric device that has copper windings will have some of this varnish on the wires. This is to keep the winding from shorting out to one another. The number of windings are specific for the intended voltage that is to be used. So if you short out some of the wires to each other, you are going to reduce the number of winding and it will affect the solenoid, relay, or what have you. The insulating varnish is usually some shade of red or reddish brown, but I've seen a few other colors, too.

Looking around in old electric devices has given me more than a lifetime supply of copper wire. From larger gauges all they way down to wire that I could put on a size 32 hook.

Brian