I received my griswold #12 skillet preserved with stove black. It would not come off with alcohol, soap and water or a trip through the fire place. In fact, all of those methods would lead you to believe it had been cleaned up. Until, you rubbed it down with oil and that as it turns, out was the cure. So, a few cups oil olive oil and about a half a roll of paper towels later and lots of elbow grease I had a cleaned skillet that we have been cooking on for about a week now. It has a beautiful mirror slick cook surface.