Cast-iron cookware
Because other cookware cleaning techniques like scouring or washing in a dishwasher can remove or damage the seasoning on a bare cast-iron pan, these pans should not be cleaned like most other cookware. Some chefs advocate never cleaning cast-iron pans at all; simply wiping them out after use, or washing them with hot water and a stiff brush. Others advocate washing with mild soap and water, and then re-applying a thin layer of fat or oil. A third approach is to scrub with coarse salt and a paper towel or clean rag.
Surface chemistry of cooking
Cast iron cookware is seasoned with oil. The surface of the cast iron is not very smooth; it has pits and peaks that are not conducive to cooking. Typically, the cookware is seasoned with oil. This process leaves a thin coat of oil in the pits and on top of the peaks on the surface of the pan. This thin coat actually polymerizes, making it durable and lasting. It also prevents the cast iron from rusting, which it is prone to do. The oil that is used in a seasoned pan combines with any liquid that is used in the cooking process and creates a good contact between pan and food. Even though the cast iron itself is a poor heat conductor, the oil makes the pan effective when it is at a high temperature.