A while back I shared the sad story of how I neglectfully let one my darling cast-iron skillets rust, and an old frontier trick I discovered for getting her back to good health. I mentioned at the end that removing rust also means removing the most important feature of a good cast-iron piece, its non-stick seasoning layer.

“Seasoning,” in this sense, doesn’t refer to flavoring. It’s more like curing. When you buy a new piece of cast-iron (unless it’s one of Lodge’s pre-seasoned products) you’ve got to give it a little lovin’ and a hot grease bath before it reaches its prime condition.

By burning a finish of lard, shortening, vegetable oil, or bacon fat onto the surface of your cast-iron, you create a protective coating that acts much like the fancy, modern non-stick cookware popular today, without all of the chemicals. Foodstuffs glide along the surface, fried eggs flip without so much as a string of stuck white, and, as long as that coating stays intact, rust doesn’t stand a chance.

Any time your seasoning layer is compromised, though (whether it be by letting food sit in it too long after cooking, taking a sharp or metal tool to it, running it through the dishwasher or, as I learned as a kid, scrubbing it with soap and a sponge), you’ve got to repeat the seasoning process to restore it.

It’s pretty easy to do.

Step 1: Preheat your oven to 350˚F.

If you’re working with a brand new piece, wash it well. Sponge and soap are fair game when it’s brand new, to get it nice and clean and take off the factory coating used to prevent rust before it’s bought.

If you’re re-seasoning, you’ll also want to clean it up, but just with hot water and a paper towel. If it’s got any gunk stuck to it, try scrubbing it with a paper towel and coarse salt over low heat on the stovetop.

Make sure it’s completely dry.

Step 2: Use a paper towel to cover the entire piece with a thin layer of fat such as lard, shortening, vegetable oil, or bacon fat. Stay away from low smoke-point stuff like butter or margarine. Coat it inside and out, including the lid if it has one—remember that we’re not just preventing stick, but also rust.

Step 3: Line a baking sheet with tin foil and place it on the lower rack of your oven. Then put your coated pot or pan face-down on the top shelf. The lid, if you have one, can stay face-up. Make sure they’re lined up with the sheet on the bottom, which will catch the fat as it drips off.

Step 4: Set a timer for an hour. Once it’s done, turn off the oven, open the door, and walk away for a while to let it cool off.

That’s it! Make sure to be careful when you remove the piece from the oven, as it holds onto heat for quite a while. Don’t be alarmed if it smokes a bit the first few times you use it—that’s normal.

A few other tips for building up and maintaining your cast-iron seasoning:

• Cook something nice and greasy the first few times you use your pot or pan, which will reinforce the brand new seasoning layer. Bacon or sausage work great. For the veggie heads, try refrying beans or making home fries.
• After each use, wipe your skillet or pot clean right away (using the above salt-and-paper-towel method to remove any gristle). Don’t be lazy! Letting food sit in your cast iron will screw up the seasoning.
• Apply a very light coat of oil all over the inside before you store it. Don’t use lard or bacon fat for this step—you don’t want to use anything that might go rancid if it sits for a while before being used again.
• It’s okay to wash your skillet with hot water and the soft side of a sponge every now and then. Just be very gentle, and make sure it’s completely dry and oiled up before you put it away. Try heating it for a minute or two on the stove to evaporate all of the water before you wipe it down with oil.
• Store Dutch ovens and other covered pieces with the lid off. Cast iron requires air circulation.
• Just about the only thing you shouldn’t do in a cast-iron piece is boil water. This will mess up your seasoning and encourage rust.
• Any time you begin to see pock marks, a dullness in color, rust spots, etc., it’s time to re-season.