Easy Off oven cleaner, brake fluid, Simple Green, Casterol Super Clean, and Purple Power have all been used to remove enamel paint. I listed EASY OFF which is a brand name, however MOST oven cleaners and/or drain cleaners will work IF they use Sodium Hydroxide (Caustic Soda). Be careful as some brands do not. If you can find a hardware store that still sells plain granulated Caustic Soda you can use it rather than a brand name oven/drain cleaner. On Ebay you can buy pure Lab grade Sodium Hydroxide. Eye and Hand protection are a must and keep away from aluminium.