People will tell you all sorts of things about cast iron. Don’t use soap! Don’t cook tomatoes in it! Don’t get it wet or feed it after midnight!
Relax. Cast iron care is simple. Here are the two biggest things to remember.
- Dry it before you put it away.
- Don’t put it in the dishwasher.
Easy, right? If want to learn about seasoning cast iron, or why cooking tomatoes in a cast iron skillet would even be problematic, keep reading.
WHAT IS THIS MYSTERIOUS “SEASONING”?
Seasoning is what makes cast iron black. The blacker a skillet, the better it is seasoned.
“Seasoning” refers to a finish, and also to the process of applying that finish. Generally speaking, Oil + Metal + Heat = Seasoning.
When thinly spread over the cast iron and heated for a long period of time, the fatty acids in oil change chemically, oxidizing and creating a slick layer over the surface of the pan. To the naked eye cast iron looks smooth, but it’s got teeny-tiny nooks and crannies where the oil gets trapped and then bonds with the iron.
So, when you season cast iron, you’re making a do-it-yourself nonstick coating. Cool, huh?
SEASONING GETS BETTER OVER TIME
The more you cook with cast iron, the better that coating gets. Cast iron is best suited for people who want an evolving relationship with their cookware. The process is the point.
For best results, get in the habit of seasoning your skillet after most uses. Routine seasoning isn’t hard, and it doesn’t take a lot of time.
Most new skillets these days come pre-seasoned and ready to use. We’ll get more into seasoning in a bit.
HOW TO CLEAN CAST IRON
About that soap: I occasionally wash my cast iron cookware with dish soap on purpose. It’s fine. It will not ruin your skillet. When your skillet is especially greasy, a little dish soap cuts right through it.
But often it’s not necessary to wash cast iron with soap. If you’ve been griddling pancakes, a simple wipe with a paper towel might be all you need. For gunky or saucy foods, keep reading.
SCRUB AWAY YOUR WORRIES
For gunky, saucy residue, a wet plastic scrubby or brush gets the job done nine times out of ten. Avoid metal bristles or pads, which can remove the skillet’s seasoning.
Once your skillet has cooled off some, fill it with water, scrub-a-dub-dub, rinse, and presto! It’s clean.
I save the plastic netting from bags of onions or fruit for single-use scrubbies—they work great, especially for crud like melted cheese or cooked egg residue.
Old-time cleaning methods include scouring the skillet with salt or cornmeal. Both of these abrasives are likewise safe and cheap.
HOW SHOULD I DRY MY SKILLET?
Don’t store your cast iron while it’s still wet because Iron + Water = Rust.
How do you dry a skillet? Sounds obvious, but with a towel (cloth or paper). You can let it air-dry, but that could lead to small spots of rust developing if the air circulation is poor.
Some people like to dry their skillets on the stove over low heat for half a minute or so. This works, but if you wander away and forget the skillet is on the stove, you can return to a smoking, red-hot skillet. Not like I’ve ever, ever done anything like that. (Note to self and others: set a timer.)
WHY CAN’T I PUT CAST IRON IN THE DISHWASHER?
I’d always heard dishwashers can strip away the seasoning and make cast iron rust. But I’d never tried it myself, so—with the thrill of rebellion—I did.
It’s not a myth: my skillet came out rusty, and I needed to re-season it.
HOW TO SEASON CAST IRON
I’d be lying if I said I seasoned my cast iron every time I used it. Routine seasoning after most uses is probably good enough.
Here’s how to do it: once your skillet is clean, set it on the stove over high heat until it’s dry. Add a small amount of oil—less than a teaspoon—and smear it around well with a paper towel or clean, lint-free rag. Take it off the burner. If it looks especially greasy still, wipe it out again. That’s it!
The seasoning on your skillet isn’t permanent. It can ebb and flow, depending on what you cook. Frying and sautéing, which involve heating oil, build the seasoning up. But after simmering liquids in your skillet, the seasoning will be duller and more vulnerable to rust. Dry-searing in your skillet—as well as unintentionally burning food—can also wear down the seasoning.
When your skillet isn’t looking like its normal self, give just it some extra love and a good massage with oil as described above. Think of it as its stint at the Skillet Spa.
WHAT OIL TO USE FOR SEASONING
Lard was once the fat of choice, but do you have lard around? Probably not. Also, animal fats (like lard or bacon grease) can go rancid. As can olive oil. This said, if you use your skillet every single day, then it’s fine to use these fats for seasoning.
But in general, you want to use an oil with a high smoke point when you season cast iron, particularly if the cast iron was in bad shape. So-called neutral oils like soybean oil, vegetable oil, and canola oil work fine.
For routine seasoning, I’d say don’t get too hung up on the specific kind of oil; it’s better to season with an oil that’s not the top choice than it is to neglect to care for your skillet.
HOW TO RESCUE A RUINED SKILLET
So you found an old skillet at a flea market. Or you put one in the dishwasher. Or you accidentally carbonized a block of tofu. In any case, now the skillet looks like something brought up from Titanic wreckage. Can you save it?
- Step 1: Preheat the oven to 350°F.
- Step 2: Scour the skillet’s rusty spots with dry steel wool or a metal scrubby. You’ll wind up spreading the loosened rust particles around, and it might not look like you’re making headway. If you wipe away the rusty dust with a paper towel and you’ll see that you are.
- Step 3: Wash the skillet in warm water, scrubbing it with a stiff brush or scouring pad. You can use a little dish soap, if you like, but it’s not necessary.
- Step 4: Dry the skillet. If you see rough, rusty spots repeat steps 2 and 3.
- Step 5: Give your skillet a massage all over with neutral cooking oil such as canola or vegetable oil. Use a lint-free rag or paper towel. Don’t be skimpy, but don’t slather it, either—that can give your seasoning a sticky residue.
- Step 6: Put the skillet face-down on a rack in the middle of the oven (face-up might cause oil to pool, leaving a sticky residue). Lay a sheet of foil underneath to catch any drips. Bake the skillet for 1 hour. Turn off the oven, and let it cool with the skillet in it (put a Post-It on there so you don’t forget).
- Step 7: Once the cast iron has cooled, examine it. Repeat steps 5 to 6, if needed. If the situation still looks grim, it’s time for drastic measures.
COOKING ACIDIC FOODS IN CAST IRON
Acid—things like vinegar and tomato sauce—will react with the iron in the metal as they heat. This can cause a metallic taste.
The rule of thumb here is moderation: shorter cook times and mild acids. Reducing a bottle of balsamic vinegar in cast iron is a bad idea; tomato sauce simmered for half an hour or less should be fine. Also, sauces are less likely to pick up metallic tastes from well-seasoned pans.
Storing acidic foods in cast iron can also lead to a metallic taste. I noticed this after eating a berry cobbler I’d baked the day before and left in the skillet. You can avoid this by transferring the food to another container once it’s cool.
COMMONLY ASKED CAST IRON QUESTIONS!
- How do I store cast iron? If you have a pot rack, hanging it is the best way, because it allows air circulation for better drying in case there’s any water still on it. It’s also fine to stack skillets on top of each other in a cupboard. Some people like to put paper towels between skillets, but it’s not necessary; the seasoning won’t chip off.
- My cast iron skillet is sticky. You probably used too much oil when you seasoned it last. If it’s really bothering you, you can strip away the seasoning and start from scratch, using a lighter hand with the oil this time.
- My pan gets a little rusty every time I use it. You are probably not using enough oil when you season it. Or you’re just not seasoning it, period. Follow the directions we gave above and you’ll soon be in good shape.
- I have small charred spots of residue showing up in the food I cooked in my skillet. You have a film of burned food still in your skillet. You must have done a number on it last time you used it! Burned food is black, like your cast iron, so patches of it can be hard to spot. Boil water in your skillet for 5 minutes or so to loosen that residue, dump the water down the drain, and then scour the skillet with a brush or plastic scrubby once it’s cool enough to handle.
- When I cook eggs, they stick to my skillet. The proteins in egg whites tend to form bond with metal—particularly with iron—and this is what makes them stick. I’ve noticed older eggs with runnier whites tend to stick more—maybe because they cover more surface area, who knows. In any case, keep at it. Make sure you’re adding enough fat to the pan when you cook your eggs. Practice makes perfect. And the better the seasoning, the less eggs will stick.
- Can cooking acidic foods in cast iron add iron to my diet? Yes, if you can believe it. I’m anemic, which means the iron levels in my blood tend to be low. Cooking acidic foods in cast iron is a great way to get your iron intake up. Just how much depends on what you are making and what you serve it with (calcium-rich foods, for instance, inhibit your body’s absorption of iron).
- Can it add too much iron to my diet? Cooking acidic foods in cast iron won’t make you O.D. on iron. Any food that rich in iron would taste like old nails, so you’ll know at once if it’s a problem.
TRY THESE RECIPES FOR SOME QUALITY TIME WITH YOUR SKILLET!
- Cornbread in a cast-iron skillet has an irresistible golden-brown crust.
- It’s easy to fry eggs in cast iron when you know a few tricks.
- Pork chops and cabbage is a one-skillet dinner.
- Saucy skillet chicken puttanesca proves you can cook tomatoes in cast iron.
- Skillet peach crisp is a summertime dream.
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