Apparently, the baked/dipped varnish adhered better to the wire lacquer than the lacquer adhered to the copper itself...

This was another confirmation of my plan to never ever bother with re-used copper wire. Others seem to get good results though. But apart from living on a (nearly-) deserted island (Hi Oz ;) ) I think it'd be much wiser to spend a few $$ and buy new wire.

At least, it's what I do.

Would be a shame after having spent dozens of hours building a generator having to arrive at the conclusion that it doesn't work because the wire insulation failed.

Also notice that the back-and-forth bending of the copper wire stress hardens it. It becomes harder and more brittle and may break when bent a few more times again. And become more susceptible for fatigue.

Anyone who knows me know I'm a scrounger, but sometimes one needs to use the best quality materials available. In the case of generators, that would be copper wire, magnets and epoxy. One could compromise a bit on the other parts, I suppose.