the good things for getting PC off, once it's softened up and hopefully sluffing off the work piece: wire brush (already mentioned) and very coarse steel wool. If working with a soft metal, like aluminum where deep scratching needs to avoided, another good tool is a scraper fashioned from a piece of wood. I used a piece about 3/4 x 7 x 1/4". Sharpen the 3/4' end like a chisel. This will allow you to get under well softened PC and scrap it off in strips. It won't clog up like steel wool and can remove a lot of material fast since you can get down to the metal right from the start. Does need to be sharpened frequently (hardwood would be the best) and wear heavy leather gloves to avoid driving splinters into your hand if it breaks. Wasn't a problem for me, but a danger nonetheless.
