No it doesn't have to be flamed. MIneral spirits and a scotch brite pad will do the trick. Basically what your trying to do is get rid of the oils. Acetone will work also to clean it. Although the smell is stronger than mineral spirits.
It is not burning it. You are just midley warming it up so that the wax film on the coroplast is removed. If the heat is left on to long it will melt and or bubble the coroplast making it useless. Good Luck, Dave
Medium Zap. Use drops not big blobs. Or use a top flite woodpecker and use Gorilla Glue or Elmers polyurethane glue. Elmer's polyurethane is about hal the price as Gorilla glue. Just does'nt foam up as much. I'm Cheap i use the elmers.