Perhaps you've just rescued an old cast iron skillet from a resale shop or yard sale. Perhaps you inherited a neglected Dutch oven from a relative or friend. Or worse, you find you've unknowingly abused your own treasured piece.
Don't fear. There is hope to repair that abused and neglected piece of cast iron cookware. With a little work and the right tools, you can repair a cracked treasure. But understand that its days as a useful cooking vessel are over. Your piece can only be put on display.
Clean the piece of cast iron thoroughly with hot soapy water and a stiff nonmetal brush. The Griswold & Cast Iron Cookware Association says that it is fine to use soap at this point, because you will later re-season the pan. Use steel wool to remove all traces of rust. Rinse and dry the pan completely.
Evaluate the piece critically; look for cracks, warping or other damage.
Cracked cast iron cookware is very difficult to repair and requires a thorough knowledge of welding. Seek out a welding expert if you do not have the skills or equipment to repair the piece.
Warped cast iron and pieces with holes should not be repaired. Consider displaying the piece if you find you can't part with it.
If the pan shows no other signs of damage aside from the finish, move on to Step #7, re-seasoning.
Weld the cracks. Drill a small hole at each end of the crack to reduce the chance the crack will get bigger while you heat and weld the piece. Be sure to wear welding goggles and fireproof clothing protection.
Heat the crack and the surrounding area slowly to a temperature of 500 to 1,000 degrees Fahrenheit.
Weld the crack in short intervals, so you do not overheat the piece. Peen the weld. Allow the piece to cool very slowly.
Grind off any excess welding material. Apply a metal primer or sealant to the weld to prevent rust. Paint the pan if desired.
Re-season the pan, and store it in a dry place. If you stack pieces, the Griswold & Cast Iron Cookware Association recommends that you place a piece of paper towel between the items.