I understand now after using some wire that was "heated" (aka put through a fire, I didn't do it a customer did and then sold it at a higher price. Putting copper in fires to burn off the insulation is illegal here). It works okay, but the bonsai wire is better because it bends easier and it won't hurt the tree. Even copper wire that is burned is not easy enough to bend, and it can hurt the tree but cutting into and/or removing some of the bark. I'm going to invest in some real bonsai wire for the sake of my trees, it might cost more but my scrap yard wire isn't doing the job. It's hard to get the small twists without injuring the bark. And removing the wire is just as difficult.
Thank you,
Valerie