Do you cook with really old iron skillets? This might help you. Get some heavy duty oven cleaner and coat your old skillet in it. Put the pan in a plastic bag, and let it sit for a few days. Take the skillet out and wipe it down with a vinegar and water mixture, while heating it on the stove. Next, wipe down the skillet and coat it with a layer of Crisco. Stick the pan upside down in the oven for an hour, re-applying a layer of Crisco every ten minutes. At the end of this process, you will have a brand new skillet.