Can I cook on an enamel-coated 3CB? I've read that I can but the enamel will scratch unless I put down a piece of something (?). Have you tried this? Will I be able to boil water with (or without) the something? I am less concerned about scratching the enamel than I am about being about to boil water. (I found a good deal on a used 3 CB, otherwise I'd go with straight cast iron.)