The Complete Cast Iron Care Guide

The seasoning on a cast iron pan is not a coating -- it is a polymer layer formed when oil molecules bond with the iron surface through a process called polymerization. The key is using the right oil. Oils with a high proportion of polyunsaturated fatty acids, such as flaxseed, grapeseed, or vegetable oil, polymerize most effectively when heated. Each layer of oil applied and baked in at 230C for one hour adds another thin, hard coat. Over time -- and after many cooking sessions -- the surface becomes increasingly non-stick and virtually impervious to rust.

The most common mistake with cast iron care is soap. A little mild dish soap used occasionally will not destroy a well-established seasoning, but harsh detergents, steel wool, and soaking in water will. After cooking, rinse the pan with hot water and scrub with a stiff brush while still warm -- food releases easily. For stubborn bits, add water to the pan and heat briefly on the stove. Dry the pan completely on the hob over low heat and wipe with a tiny amount of oil before storing. Never let cast iron air-dry as moisture and oxygen cause rust almost immediately.

If your cast iron has rust spots or a sticky, uneven surface, a full re-season is straightforward. Scrub with steel wool and soap to remove all old seasoning down to bare metal. Dry completely in a warm oven. Apply a thin layer of oil all over -- including the outside and handle -- then bake upside down at 230C for one hour. Repeat three to five times for a solid base. The pan will look like new and perform better than ever. Many excellent vintage pans are rescued this way from thrift stores and estate sales.