Cast iron pans are heavy-duty cookware that lasts for decades with the proper care. Improper cleaning, drying or storage of a cast iron pan can result in rusting and pitting of its surface. This looks unsightly and also is unsanitary in cookware. Cleaning cast iron is not a difficult task and only requires common household supplies. Once you remove the rust and re-season the cast iron pan it will be like new.
Sand the rusted and pitted areas of your cast iron pan with the sandpaper or steel wool. Rub the area until all the rust is gone.
Wash the cast iron pan thoroughly with hot water and a squirt of mild dishwashing liquid. Scrub all the surfaces with a stiff nylon bristle brush. Please note that the only acceptable time to use soap on cast iron is when you are about to re-season it.
Rinse the cast iron pan well and dry it completely with a soft cloth.
Melt about a 50 g (1/4 cup) of solid vegetable shortening in a microwave-safe dish. This takes about 20 to 30 seconds in a microwave on a low setting.
Rub the entire surface of the cast iron pan with the melted shortening -- this includes the back of the pan and the handle.
Set your oven to 177 to 204 degrees Celsius (350 to 400 degrees Fahrenheit).
Lay a sheet of aluminium foil on the bottom rack of your oven. This catches any oil drips, and saves you having to clean your oven.
Place the cast iron pot upside down on the top rack of your oven. Leave it in the oven for at least an hour and then turn the oven off.
Keep the cast iron pot inside the oven until it is cool to the touch. Remove the pot from the oven and store it in a cool, dry area.
Clean your cast iron pot after each use by placing the cooled down cast iron under hot water and scrubbing it with a stiff nylon brush. Dry the cookware thoroughly and rub some vegetable oil lightly over the cooking surface. Store it in a cool, dry area.
Never allow the cast iron to air-dry. This causes rusting and pitting of the surface.