All well-maintained cast-iron skillets will become more nonstick with time. While you might think this will take years, we found a significant difference in our pans after just a few weeks of regular use in the test kitchen. However, even new preseasoned skillets are not always 100% nonstick when you first cook with them, and a well-seasoned skillet will still become less nonstick without proper maintenance, so it's important to treat your cast-iron skillet with care. Properly maintaining the seasoning on your skillet begins with properly cleaning it. Here are a few guidelines for keeping your pan in optimal shape. (These guidelines are for traditional cast-iron skillets; enameled skillets can be treated more like other pots and pans.)

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. That’s why even though most skillets these days come with a factory seasoning, the surface will become even more nonstick with repeated use.

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. An easy way to test a skillet’s seasoning is to fry an egg (heat 1 tablespoon vegetable oil in skillet over medium heat for 3 minutes, then add egg). If your pan is well-seasoned, you should not experience any major sticking.

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. But cheaper oils such as sunflower and soybean are also highly unsaturated and work fine.

Properly maintaining the seasoning on your skillet begins with properly cleaning it. Here are a few guidelines for keeping your traditional cast-iron pan in optimal shape. (Enameled skillets can be treated more like other pots and pans.)

Even if you routinely clean your skillet after every use, there will likely come a time when it requires a higher level of service. In those cases, use this cleaning method to bring it back to its original condition.

Over the lifetime of a cast-iron skillet, you’ll usually just maintain or touch up its seasoning. But if the seasoning becomes very dull or damaged (seasoning flakes off) or if it badly rusts (can’t be scrubbed away), you’ll need to give it an overhaul by stripping and reseasoning the surface. If this happens, use these steps to strip a cast-iron skillet—that is, completely remove any residual seasoning on a cast-iron pan before reseasoning it. Easy-Off is a caustic alkali, so be sure to work outdoors, wear rubber gloves, and avoid spraying near your face or skin. The pan will rust instantly after the seasoning has been stripped, so immediately apply oil to the surface and proceed with oven repair after step 4.

1. Working outdoors, place concrete block on ground and cover with heavy-duty kitchen trash bag, draping bag over block so that sides will be easy to grasp and pull up over the skillet. 

2. Place skillet upside down on top of block. Wearing rubber gloves, spray skillet all over with Easy-Off Oven Cleaner [Buy On Amazon], being careful to keep the spray away from your face and exposed skin. Flip skillet over and spray inside. Pull plastic bag up and around skillet and tie to close. Leave outside (or in garage) for 24 hours. 

3. Still wearing rubber gloves, remove plastic bag and scrub skillet all over with steel wool and hot soapy water to remove all residue. Rinse, repeat scrubbing, and rinse again. 

4. Combine 2 cups each white distilled vinegar and water. Fill skillet with vinegar solution and let stand for 30 minutes to 1 hour. Discard solution in skillet and use remaining solution to wipe outside of skillet. Rinse well and immediately apply oil to surface. 

5. Follow our oven repair method in Level 2 section above, repeating it six times or until skillet has a smooth, dark black, semiglossy finish.