Harry Rosenblum, co-owner of the Brooklyn Kitchen, says that rusty cast iron is easy to fix. Simply scrub the rust off with a Brillo Pad or sandpaper, wash the pan clean and dry it, cover it in a thin coat of oil, and bake it in an oven at 275 degrees Fahrenheit for an hour. Then turn the oven off, leaving the pan inside to cool slowly. This is a great tip to keep in mind when shopping at flea markets—old cast iron can be made good as new!