How do I go about removing old paint and varnish from metal hinges? I tried soaking the hinges in paint thinner and the varnish seemed to soften up a bit, however the paint wouldn't budge. I can remove bits and pieces of the paint and varnish by scrapping it with a sharp knife but it also scratches the metal hinge. So far all I am doing is putting deep scratch marks into the metal hinge and very little paint/varnish is removed. I thought of using paint remover but am afraid that the metal will corrode badly. What options do I have?