Restoring Cast Iron
How to Clean and Restore a Rusty Cast Iron Pan
Scour the rusty pan with warm, soapy water and steel wool. It's okay to use soap since you are preparing to re-season the cookware. Rinse and hand dry thoroughly.
Apply a very thin, even layer of cooking oil to the cookware (inside and out). If you use too much oil, your cookware may become sticky.
Place the cookware in the oven upside down on the top rack. Place a large baking sheet or aluminum foil on the bottom rack to catch any excess oil that may drip off the cookware. Bake at 250 degrees C for one hour. Allow to cool and repeat as necessary to achieve the classic black patina.