Cast Iron Skillet Cleaning and How to Keep It Seasoned

The short version: Wash cast iron with hot water, a stiff brush and a little soap if you need it, dry it completely on the heat, then wipe on a thin layer of oil while the pan is still warm. The "never use soap" rule is nonsense that's been repeated so often people believe it's gospel, and it's the main reason so many pans end up sticky and dull instead of non-stick.

I didn't grow up cooking with cast iron. I came to it in my forties when I got fed up with non-stick pans that scratched and died within a year. Once I understood the actual chemistry of seasoning rather than the folklore around it, the whole thing stopped being fiddly and started being one of the lowest-maintenance bits of kit in my kitchen.

What seasoning is

Seasoning isn't a coating you buy or a magic layer that appears overnight. It's polymerised oil. You heat a thin film of fat on the iron past its smoke point, it breaks down and bonds to the metal's surface, and over repeated cycles you build up layers that create that smooth, dark, slightly glossy non-stick surface. Every time you cook with a bit of oil and heat the pan, you're adding a micro-layer to that finish. That's why a well-used skillet gets better with age, not worse, and why a brand-new one from the shop always feels a bit grabby.

Cleaning a cast iron skillet after cooking

Here's the process I use, and it takes about three minutes:

• Clean the pan while it's still warm, not stone cold. Stuck-on food comes off far more easily when the pan hasn't fully cooled.
• Run hot water into the pan and scrub with a stiff brush or a chainmail scrubber. For normal cooking residue, that's all you need.
• If something's really stuck (burnt cheese, scorched egg), a drop of washing-up liquid won't strip your seasoning. Modern seasoning is polymerised fat, chemically changed from its liquid form, and a bit of soap doesn't dissolve it any more than it dissolves the pan itself. That "no soap, ever" rule got passed down from older soaps that contained lye, which could strip cast iron. Today's dish soap doesn't do that.
• Avoid soaking the pan in water. Leave it sitting in the sink overnight and you're inviting rust, especially on the parts of the surface that are less built up.
• Never put it in the dishwasher. The combination of prolonged soaking, harsh detergent and heat cycles will strip seasoning and can leave rust spots within one or two washes.

Drying is the step people skip

This is where most ruined pans go wrong, not the washing. Towel-dry the pan, then put it back on the hob on low heat for two or three minutes. You're not trying to cook anything, you're driving off every last bit of moisture, including what's hiding in the pores of the iron and around the handle rivets. Air-drying on a rack looks fine but leaves enough residual damp to start a rust bloom overnight, especially in a humid kitchen.

Oiling after every clean

While the pan is still warm from drying, add about half a teaspoon of oil and rub it in with a paper towel or cloth until the surface looks almost dry, not greasy. You want a film so thin it's barely visible. A pan that looks oily when you put it away is a pan that'll feel tacky next time you use it, because excess oil doesn't polymerise cleanly, it just goes gummy.

For oil choice, flaxseed oil gets recommended a lot online because it polymerises hard, but it also flakes more easily over time and isn't what I'd reach for day to day. Plain vegetable oil, sunflower oil or a neutral oil you already have in the cupboard works perfectly well for ongoing maintenance. Save the specialist oils for a full re-season, not weekly upkeep.

A worked example: reviving a neglected pan

Say you've inherited a cast iron skillet that's been sitting in a shed or garage, with patchy orange rust across half the surface and the rest looking dull and grey. Here's roughly what bringing it back looks like:

• Scrub the rust off with steel wool or a scouring pad under running water until you're back to bare grey metal. Don't worry about being gentle here, you're not trying to protect existing seasoning because the rust has already ruined it in those spots.
• Dry it completely, then heat it on the hob for a few minutes to make sure every trace of water is gone.
• Rub a thin coat of oil over the entire pan, inside, outside and handle.
• Put it upside down in an oven at around 230°C with a tray on the rack below to catch drips, and bake it for an hour.
• Let it cool in the oven, then repeat the oiling and baking step two or three more times.

By the third or fourth round you'll have a dark, even, non-stick surface. It won't look identical to a pan that's had twenty years of regular use, but it'll cook a fried egg without sticking, which is really the only test that matters.

What damages seasoning

A few specific things cause more harm than soap ever does:

• Cooking very acidic food for long periods. A quick tomato sauce is fine. Simmering a chilli or a long-cooked tomato ragu for two hours in the same pan week after week will slowly eat into the seasoning, because acid breaks down the polymerised layer over time.
• Letting it sit wet. Rust forms within hours in a damp kitchen, not days.
• High heat with no oil. Dry-heating an empty pan to blazing hot temperatures repeatedly stresses the seasoning layer and can cause it to crack or flake.
• Metal scourers used aggressively on a well-seasoned surface. Fine for stripping rust, overkill for everyday cleaning once the surface is built up.

The uncomfortable bit nobody wants to say

Here's what most cast iron guides won't tell you plainly: your skillet does not need to look flawless to work brilliantly. A patchy, slightly uneven, two-tone surface with a few lighter spots is completely normal and still cooks a perfect steak. People get so hung up on achieving that glossy, jet-black Instagram finish that they over-oil, over-season and end up with sticky build-up instead of a working pan. Function matters far more than appearance here. If your eggs slide out cleanly, stop worrying about how the pan looks in photos.

Storage between uses

If you're stacking pans, put a paper towel or a thin cloth between the cast iron and whatever sits on top of it, to stop moisture transfer and scratching. Keep it somewhere dry, not under the sink where condensation and damp are more likely. If you're not using a pan for a while, say over a holiday or a season, give it a slightly heavier coat of oil than usual before you put it away.

Frequently asked questions

Can you use soap on cast iron?

Yes. A small amount of ordinary washing-up liquid will not strip seasoned cast iron. The old rule against soap dates back to lye-based soaps, which could damage the surface. Modern dish soap doesn't contain lye and is fine for regular cleaning.

How often should you re-season a cast iron skillet?

If you cook with it regularly and oil it after each wash, you shouldn't need a full re-season more than once or twice a year, if that. A full strip-and-rebuild is really only needed after rust, a dishwasher accident, or long periods of neglect.

Why is my cast iron skillet sticky after oiling?

You've used too much oil. The fix is to wipe the pan with a dry cloth until almost no oil is visible, then heat it on the hob for a few minutes to help the thin layer bond. Too much oil goes gummy instead of polymerising cleanly.

Is it safe to cook acidic food like tomato sauce in cast iron?

Occasional use is fine on a well-seasoned pan. Regularly simmering acidic sauces for long stretches will gradually wear down the seasoning, so it's worth keeping a separate pan for those longer, acid-heavy recipes if you cook them often.