Cast Iron Kit

The Science of Seasoning

When fat or cooking oil is heated for a long enough time in cast iron, its fatty acids oxidize and reorganize together (or “polymerize”) into a new plastic-like layer of molecules. This layer becomes trapped within the pitted surface of the pan and bonds to the metal itself, creating the slick coating known as seasoning. Repeated exposure to hot oil continues to build on this coating, making it more slippery and durable.

What does "well-seasoned" mean?

A well-seasoned skillet will have a dark, semiglossy finish and won’t be sticky or greasy to the touch. It won’t have any rust or any dull or dry patches.

Use the right oil

The more unsaturated the oil, the more readily it will oxidize and polymerize. We have found that flaxseed oil, which oxidizes and polymerizes faster than other vegetable oils, forms a particularly durable seasoning.

MYTH: You should never wash cast iron with soap.

The Testing: During our extensive recipe-testing process we generated hundreds of dirty skillets and thus had plenty of opportunities to test different cleaning methods. While developing our recommended procedure, we experimented with a variety of cleansers, including dish soap and scouring powders.

The Takeaway: We found that a few drops of dish soap are not enough to interfere with the polymerized bonds on the surface of a well-seasoned cast-iron skillet. Don’t scrub the pan with abrasives like steel wool or use harsh cleansers like Comet, and don’t soak the pan, since those things can definitely affect the seasoning, but it’s OK to use a few drops of dish soap if you need to clean up a particularly greasy pan, or even if that just makes you feel more comfortable with your cast iron. Just make sure you rinse the pan clean and wipe it dry when you’re finished.