A cast-iron pan is the reliable workhorse of the kitchen, but, like a real horse, it can get absolutely filthy—and people seem equally skittish about cleaning either.
Despite the fact that one of this iron-carbon alloy’s main virtues is its extreme durability (fans often talk about one pan lasting generations) somehow there’s an idea that regular old soap and water is kryptonite to cast iron because you’ll wash away the “seasoning.”
“There is a lot of misinformation out there about cleaning cast iron,” says Gregory Stahl, who is both co-founder of a Massachusetts-based society dedicated to collectors of cast iron and a graduate of Harvard Medical School.
Speaking from his experience as a medical professional, he says not cleaning a frying pan probably won’t make you sick, because frying generally requires temperatures too high for illness-inducing bacteria to survive.
But as a collector who personally owns a few thousand pieces, some worth thousands of dollars, he strongly advises regular cleaning. “If you don’t, you will eventually get a crusty buildup in the bottom of your pan from burned-on food debris,” he says.
And when that happens—when your pan gets a telltale textured bottom—your only recourse is to strip it down to the bare metal* and starting the seasoning process all over again (which is also what Stahl recommends if you come across a secondhand pan).
Lodge Cast Iron Skillet, Pre-Seasoned and Ready for Stove Top or Oven Use, 10.25
Seasoning is what protects cast iron from rust and makes for a smooth, nonstick cooking surface inside. It doesn’t take years to build up, just a few rounds in a hot oven between thin applications of oil or lard.
Because this is essentially what cooking does—oil, heat, repeat—the more you use a pan, the better it gets. But that leads some people to think they should never wash their cast iron skillets, which isn’t the case.
Sometimes, after say, grilled cheese, all you may need is a quick swipe with a dry towel. But when you’ve make a saucy mess, the best fix, says Stahl, is to fill your skillet with water and bring it to a boil on the stovetop.
Let it cool enough to scrub with a nylon sponge (anything more abrasive, like a Brillo pad, can scratch), and then dry it thoroughly to prevent flash rust, the light orange particles that appear when the iron isn’t fully seasoned. (Those can be easily scrubbed off but it’s easier to just prevent them in the first place.)
Some people will re-oil their pan after each use, but it depends on the level of seasoning you’ve achieved, says Stahl. Almost any oil will work, as will shortening or lard, as long as your pan is in regular use; if you don’t plan on using it for a while, those greases and oils with lower smoke points can go rancid. (There are products made to combat this, like Crisbee, which is made from beeswax, but Stahl says Crisco works just as well).
While cast iron is certainly sturdy enough to stand up to soap bubbles, there are two “cleaning” methods Stahl never recommends: fire and sandblasting.
There is an idea that if you stick a pan directly in fire, it will burn away all the debris. But fire is way hotter than an oven, and can actually discolor the metal, says Stahl. And where seasoning is a chemical bonding process, sandblasting strips away the actual surface of the metal, not just what’s stuck to it. After that, it can be difficult to season, he says.
And nothing about cooking with cast iron should be hard—except for the pan itself.
*Stahl’s recommended method of doing this: Spray the pan inside and out with oven cleaner and tie it inside a plastic bag to keep it from drying out. After a few days, take it out and scrub it with soap and water, then repeat until the dark patina on the pan is completely gone.