How to Season a Cast Iron Skillet

All illustrations: Heather Pieske

1. PREPARATION

The skillet you want is at least fifty years old, and right now it is probably sitting on a thrift store shelf or a yard sale table. Your first task is to locate it. Until the 1960s, the final stage in manufacturing cast iron was to machine-polish each pan until the cooking surface was as smooth as glass. New cast iron is sold unpolished, that is, fresh out of the mold, with a texture like pitted Formica. The cast iron companies claim that the new, unpolished skillets are as easy to season and as non-stick as the old, polished ones—but then they would say that. You can polish new cast iron yourself with an orbital sander and some 80 grit, followed by hand sanding with 220 grit wet-dry, then 320, then 400, then 600 for good measure, but let’s face it, you’d rather have those five hours of your life and the ridges on your fingernails intact. The skillet you want is polished already.

The question to ask yourself is, are you ready for a cast iron skillet? Are you the kind of person who likes to leave the washing up for the morning after? You’re going to have to change your ways. Are you the kind of person who moves a lot? Cast iron cookware is heavy. Your skillet will mock you by falling through the bottom of the cardboard box—yes, the one you reinforced with extra tape—no sooner than you pick it up. Count yourself lucky if it doesn’t hit your foot. Are you still living with roommates? The kind who might borrow your pan, burn food in it, and leave it to soak overnight in hot, soapy water? Good luck. Owning a cast iron skillet requires stability. It requires an ability to think in the long term. Can you live up to it? As you will see, this is not the kind of pan you can expect to cook with for a couple years and throw away once it starts to show signs of use. It’s not goddamn Teflon. Your cast iron skillet will outlive you, and your care is important, even crucial. More than anything, you should only have cast iron in your life if you love it. Now ask yourself, are you ready?

2. STRIPPING

Before you can season the nice, old polished skillet you found, the one that feels like porcelain under your fingers (“Griswold” brand, Goodwill), you must strip the pan’s flaking seasoning. First you’ll need some Easy Off oven cleaner, the kind with lye. The oven cleaner will dissolve all the grease and grime on your cast iron. It will eat right down to the bare metal. You do not want the kind of oven cleaner that says “No fumes”—that kind doesn’t have any lye in it. It’s even better if you can find pure lye, but that’s been hard to come by ever since the supermarkets figured out that lye has a small but crucial role in the manufacture of methamphetamine. Find some rubber gloves. Find an old long-sleeved shirt. Find an open window. Put your skillet inside your plastic bag, pull the gloves over your sleeves, and carefully spray the skillet with the Easy Off, letting the white foam coat it all over. Watch it bubble and rise. Do not get the spray on your skin. Seal the pan in a plastic bag, place the plastic bag in a glass baking dish, and set the dish on the windowsill in the morning sun. The sun is important—the higher the temperature, as we know from high school chemistry, the faster the reaction. After a few hours, re-glove, open the bag, and drag a fingertip through the remains of the oven cleaner, which will now be a brown-black goo. Take the pan over to the sink and gently rinse it under running water. Be careful not to splash; lye is caustic, and it will leave red welts where it spatters. (If skin contact occurs, hold the affected area under cold water for 15 minutes.) Throw away the bag. When all the oven cleaner is rinsed away, remove your gloves and wash the skillet and the glass dish thoroughly in hot water. The bare metal is the color of graphite.

Your skillet will now be cleaner, but the blackest encrustations on the pan, the spots that are basically charcoal, will still be there. That is because lye reacts with oil. It has no impact on the kind of food crud that’s so petrified no oil remains to react with; lye also has no effect on rust. If your skillet is clean but for a few bits of rust or blackened crud, take 000 steel wool and start scrubbing. Don’t forget the bottom and the handle. Anything too stubborn for steel wool can be handled with fine grit wet-dry sandpaper or a steel-bristled brush or, if there are nooks and crannies, like on a waffle iron, bamboo skewers. You could even cut up an old credit card and use it as a scraper.

After scrubbing, rinse the clean skillet in hot water and dry it immediately on the stove over a burner set to Low. Don’t ever put a room-temperature cast iron pan over high heat when it’s empty. It’s a misconception that cast iron is indestructible. Cast iron is very, very hard. But in the way of so many hard things, it is also surprisingly brittle. You should always treat cast iron tenderly, especially the old, polished pans, which are thinner and lighter than modern cast iron. (If you were to put your Griswold No. 8 next to a modern Lodge Logic skillet, you would see the Lodge is nearly twice as thick.) Never drop your cast iron pan, never store it in a place where it might fall, and never—tempting as it is, given its weight—use it as a hammer or a club; the handle could snap right off. Cast iron can handle high temperatures—its hardness means it holds its shape at heat settings that warp aluminum, stainless, or carbon steel—but you have to turn the burner up gradually.

So put the skillet over low heat. Do not let the pan air dry, because bare cast iron is extremely susceptible to rust, and any moisture allowed to dry on the metal will leave a rust spot, which you will have to scrub and rinse. Air-drying risks initiating a rinse-dry-scrub-rinse-dry-scrub infinite loop. When the skillet becomes too hot to touch with your bare hands, turn the burner off and wait.

3. SEASONING

Now that your skillet is clean, rust-free, and bone-dry, it is time to season the thing. Seasoning must immediately follow stripping. If you were to put your skillet in a cupboard in its present state, overnight you might find a thin layer of rust blooming over the surface—the naked cast iron wants so badly to rust that it will react with even the moisture in the air. Cast iron is highly porous, and it needs oil for protection and performance. The porosity of old cast iron is an impressive thing to contemplate: imagine what your pan might absorb over time, what it will witness. Pick it up—you can easily hold it with one hand—and think about how old it might be. The Griswold factory in Erie, Pennsylvania, shut down in 1957.

What you are doing when you season a pan is covering it with a thin layer of oil, then causing a series of irreversible changes in the molecular structure of that oil. These changes are known as polymerization. Under certain conditions, any oil will polymerize—the molecules will start to break down, free radicals will be released as fumes, and polymer chains will start to form. Some oils polymerize under the right amount of heat, others will do it in sunlight, or even just the oxygen in the air (linseed). If you season correctly, the polymerizing oil bonds with the pores of the iron, and under further exposure to heat, the polymer chains link up to form a durable, hydrophobic, and slick cooking surface.

Everyone agrees that to season cast iron cookware you need oil, heat, and time. But the exact kind of oil, the optimal temperature, and the right length of time are all subject to debate. Your great-grandmother seasoned her cast iron with lard; your grandmother with Crisco; your mother with sunflower oil. Every one of them thought she was right. A highly controversial 2011 Cook’s Illustrated article favored, of all things, flaxseed oil from the health-food aisle. In the face of so many conflicting claims and such marginal differences in performance, the best oil is probably the one you have nearby when the pan is stripped and dry and it’s time to begin (canola). We can all agree that using good olive oil to season cookware is just a waste.

By now, the heat from the burner will have opened the metal’s pores, and your skillet should be hot to the touch. Take a paper towel and carefully rub about a half a teaspoon of your oil all over the pan. Bowl and spouts, back and front, handle and bottom. Then take a fresh paper towel and rub as much of that oil off as you can. Buff every side. This might require a third paper towel. You want your skillet to be covered in only the thinnest micron of oil. That’s when you put your skillet into your cool oven—upside down, to prevent pooling—and bake it for 30 minutes at a temperature that’s above the smoke point of whatever oil you used, say 400 or 450 degrees Fahrenheit. Allow it to cool with the door closed. Prepare to spend all day at this.

Remove the pan from the oven. Were you expecting a big reveal, a new skillet all instantly dark and shiny? Sorry. We’re a long way from frying our first pancakes. Seasoning cast iron is like painting your nails or varnishing a table: multiple thin coats are better than a couple thick ones. Before proceeding with the next layer of seasoning, inspect the bowl of your skillet. You may notice a faint spiderweb pattern that is shinier than the rest of the pan’s surface, or even streaks of dull, brownish grease that baked but didn’t polymerize. Those are the tell-tales of an oil coating that was either too thick, unevenly applied, or both. If you don’t remedy them now, the next layer of seasoning won’t adhere properly, and sooner or later it’ll flake off. You’ll need to scrub those oil artifacts away with steel wool and salt, then rinse and dry the pan. Be more careful next time. Expect it to take at least five layers of seasoning to get your pan glossy enough to use.

4. COOKING

In the beginning you should be gentle. You should try to cook a lot of fatty foods to start with. Every time you cook something fatty in cast iron—every time you sear a steak or sauté an onion in olive oil—you are renewing the seasoning. Every time you make something particularly sugary or acidic—every time you simmer chicken in teriyaki sauce or deglaze the pan with wine—you are etching away at it. Never let food or its residue sit in a cast iron pan after cooking. Keep in mind that tomatoes are highly acidic. In general, vinegar and cast iron don’t play well together. After cooking anything that has the potential to damage your pan’s seasoning, always wash it thoroughly, dry it, warm it, and re-season it immediately.

You can cook anything in well-seasoned cast iron. You can fry an egg, bake a pie, brown meatballs, make beignets, braise lamb shanks, bake the best cornbread, even, in a pinch, boil water for pasta. What makes cast iron such a wonderful cooking surface is that it is an ineffective heat conductor. That lack of conductivity has some drawbacks—it takes much longer to come to temperature than other cookware, until heated completely it has hot spots, and once off the heat it takes a long time to cool down—but it also means cast iron excels in how it retains and radiates heat. A cast iron skillet cooks food more evenly than other cookware—once it comes to temperature, the pan keeps its sizzle even as you add cold ingredients. It goes from the stovetop to the oven and back. The thing about cooking with cast iron is that it’s fun. Proteins brown effortlessly, and then release. Baked goods slide right off. Metal utensils don’t hurt it. Once you cut through the crust of your first loaf of bread from the skillet, you won’t miss your cookie sheet. You may find you start staying in to cook. You may find you start inviting over friends and neighbors. You may find you have love in your life, maybe, for the first time, more than just enough for yourself.

Frying pork chops in your newly seasoned pan that first night is highly advisable, even if you have to Google “how long to fry pork chops” to do it. Remember how your mother used to dredge pork chops in milk and flour before frying them in her cast iron skillet, and as a kid you’d use a fork to scrape up the blackened bits of pork fat and breading while the pan was still spitting, not even waiting for them to drain on the paper towel-lined plate, not even caring that they burned your mouth.

 5. CARE AND KEEPING

The performance of your skillet will be determined by how you treat it. The best way to clean cast iron is wipe it out with a dry paper towel right after cooking. While it’s still warm is easiest. Don’t be alarmed if the pan appears clean but the paper towel still turns brown when rubbed across the bowl of the skillet. That’s normal. If food is stuck, scrub at it with salt. If that fails, boil an inch of water in the pan and see if whatever’s stuck loosens with a metal spatula; if it does, wipe the pan dry, and buff the bowl with oil while still hot. If it doesn’t, next try a sponge and some hot water. You can wash a well-seasoned cast iron skillet with dish soap, but it’s best used as a last resort. Never let your skillet sit in water. And if you put your cast iron in the dishwasher, you deserve whatever befalls you.

Dry your skillet immediately after washing. Putting it on a burner for a few minutes while you finish the rest of the dishes is a great way to do this. Maybe you would like to finish that bottle of wine? Wipe the skillet inside and out with a thin layer of cooking oil. Then buff it off.

Re-season your skillet every month, or after cooking anything acidic, whichever comes soonest, for the first year of ownership. Then re-season as needed. Remember, the more you cook, the better your skillet will be, and the more resilient. Having a skillet may require you to rethink some of your habits; it may make you think differently about the future. It will only add to your life if you want it to, if you let it. Look at that deep, black bowl. Look at your skillet, gleaming like a well. Think about all you have given it and all it gives you. Think about seasoning it again tomorrow morning.

Jenna Sauers is a writer and an M.F.A. candidate at the University of Iowa. She uses her cast iron skillet daily.