What To Do With Cast Iron After Cooking

The goal of washing a cast iron skillet isn't just to get it clean, but to keep it in top shape by priming it for further seasoning. It's a natural part of the maintenance cycle to improve the performance of your pan over time.

There's a lot of contradictory advice out there on how to clean a cast iron skillet — and a few myths to be busted. Here's what you need to know:

How to wash and clean a cast iron skillet

For simple dishes, you only need a quick wipe-out with a paper towel.

Whenever you clean your cast iron pan, we recommend starting with the gentlest, least-invasive methods. Start by wiping grease out with a clean paper towel. If it appears clean with no food residue afterwards, you can stop right there! A dry pan is an unhappy pan, and surface oils aren't necessarily a bad thing.

The Field Method

For everyday cleaning and care, we call our recommended process The Field Method. Cook often and follow these steps when cleaning up to keep your cast iron skillet in excellent non-stick condition:

Heat the pan on the stovetop until dry.

Using a cloth or paper towel, apply a dab (about ¼ teaspoon) of Field Company Seasoning Oil and rub on all surfaces, inside and out.

Wipe away excess oil to leave a dry, matte finish.

Repeat every time you cook.

To remove residue from eggs or fatty proteins, use a sturdy brush first and follow up with a chain mail scrubber.

Is it OK to use water?

Soaking a pan with water overnight is a sure recipe for rust, but a brief rinse or few minutes' soak with warm water is fine. Use a firm cleaning brush, chain mail scrubber, or sturdy non-scratch dish sponge to wipe out any bits of food. Once the pan is rinsed off, dry it thoroughly with a dish towel, and heat it on the stovetop to evaporate away any lingering moisture.

Washing with water is fine, as long as you dry your skillet thoroughly afterwards.

Once the pan is fully dry, it's time to apply a dab of Field Seasoning Oil to protect the cooking surface and build strong seasoning. The oil will provide a protective coating to prevent rust, and also readily convert to seasoning the next time you heat the pan up.

Everyday cooking oils, including liquid fats like olive or grapeseed oil, are acceptable substitutes if you're cooking with your skillet every day. But these oils aren't ideal for more than a day or two, since they go rancid in the presence of oxygen. That's why we recommend using Field Seasoning Oil : our blend of organic oils will remain stable at room temperature and won't turn sticky or produce off odors like standard cooking oils. For longer-term storage (a week or more), we recommend Field Seasoning Oil or a heavily saturated fat like lard, butter, or coconut oil.

A very thin layer of oil or saturated fat is all you need to keep your pan happy.

No matter the fat you choose, you don't need a lot of it; just enough to add a dull lustre to the pan's surface. And most importantly: the more you cook with your pan, the better it'll perform, and the easier it'll be to maintain.

Is it OK to use soap?

The old conventional wisdom around cast iron is that soap is the enemy. Back when soaps were commonly made with harsh compounds like lye and vinegar, this was true, but most modern dish soaps, especially eco-friendly varieties, are perfectly safe so long as they don't contain any polishing agents. If you have residue or strong flavors in your pan that you can't eliminate with a stiff brush and some water, by all means lather up.

A little soap is fine every now and then, but it will de-grease your pan. Make sure to oil your pan well after a soap scrub.

That said, soap is by nature a de-greaser, and while it won't strip away seasoning, it will dry out the surface of your pan by eliminating the oil on your cooking surface. So only use it if you have to, and if you do, be sure to oil the pan afterwards.

How clean is clean?

Some new cast iron owners get concerned by this advice, worrying that a briefly scrubbed or rinsed pan isn't really "clean." But the truth is, it's better your pan be too oily than not oiled enough. From a food-safety standpoint, the surface of a cast iron pan during cooking easily reaches upwards of 300 degrees, which is high enough to kill any bacteria that don't get washed away. You will not get sick from maintaining your pan this way. On the flipside, those coats of oil are crucial for preventing rust, and act as a barrier to keep water or anything else from the surface of your pan.

Remember: cast iron is porous. In the same way your old wood farm table needs a coat of mineral oil now and then to keep smooth and crack-free, your pan needs fat to turn its cooking surface slick.

How to store and maintain a cast iron skillet

It matters where and how you store your cast iron. A cool, dry space with some air circulation is ideal, as even warm, humid air can kickstart the rust-forming redox reaction. Also, resist the temptation to stack pieces of cast iron on top of each other. The iron itself is sturdy and robust, but sudden impacts and prolonged weight can harm the pan's seasoning. In our view, the best place to store a pan is right on the stove, so it's ready for your next meal.

Saturated fats like butter, lard, and coconut oil are best for oiling the pan after cleaning.

After each meal, it's important to keep the pan lubricated with a thin coat of fat (remember: a dry pan is an unhappy pan). If you won't be cooking with your pan for a while, this is especially important. A thin coat is all you need, and will go a long way to preventing rust during storage.

How often do I need to season my pan?

Field skillets come pre-seasoned, and steadily develop resilient non-stick seasoning through cooking. If you cook with your pan regularly and avoid any kitchen incidents (accidents happen!), you likely won't need to re-season your pan. Ever.

If you're inclined to give your pan special treatment once or twice a year, we recommend sticking with our cast iron seasoning instructions and using Field Seasoning Oil as your seasoning agent of choice.

Why does cast iron rust?

Even a well-seasoned cast iron pan will rust if it's exposed to prolonged moisture and air. That could mean a spot of water, an insufficiently dried-out skillet, or even humid air in a hot environment. The process is simple chemistry; in the presence of moisture, iron molecules react with oxygen molecules on a chemical level to form iron oxide, aka rust. Left to its own devices, this redox reaction will eventually convert the entire mass of iron into iron oxide. It'd take decades for a hunk of metal the size of a cast iron pan to decompose, but iron oxide does weaken the atomic bonds in cast iron, and can eventually cause pitting that damages seasoning.

If your pan has developed rusty patches that don't wipe away with a lightly oiled paper towel, gently scrub the affected area with a tablespoon of kosher salt as an abrasive. Ease your way into more abrasive sponges, then Barkeepers Friend, with #00 steel wool as a last resort. Your goal is use the gentlest tools possible so you don't damage layers of well-earned seasoning.

Once you've cleared the patch of rust away, dry the pan with a kitchen towel, then place it on a stove on low heat for 10 minutes to completely dry the surface. Some of the rust may re-appear at this stage; this is normal. Pour ¼ teaspoon of oil or solid fat (we recommend a saturated fat like coconut oil) onto the affected area and use a clean paper towel to wipe it into the metal. Wipe away all excess fat—you shouldn't see any oil sheen—and return the pan to low heat for 10 minutes to bake the fat in.

If all that scrubbing has removed some seasoning, you'll want to re-season the pan in the oven once or twice. Follow our cast iron seasoning instructions, and start cooking!

Remember, the best way to treat rust is to prevent it from happening in the first place: whenever you use your pan, make sure it's thoroughly dry after cleaning, and well-oiled before you put it away.