My roommate unfortunately heated up some rock salts in my cast iron skillet and added an essential oil when she did so. I have tried many things: boiled vinegar in it & letting it cool, rubbing it down with a baking soda paste, letting vinegar & baking soda sit in it over night, heating a neutral oil in it & washing it. But the smell of the essential oil still persists when it is heated. Any other suggestions? I really don't want to get a whole new cast iron skillet & start over again!