Why Is My Cast Iron Rusting? (And How to Fix It Fast)

Rust on cast iron isn’t a mystery. It’s chemistry.

When bare iron is exposed to water and oxygen, it oxidizes (i.e. rusts). If your seasoning layer is intact, it protects the metal. If that layer is thin, scratched, or compromised, moisture gets in and rust forms, sometimes in a matter of hours.

The good news: rust on the surface of your pan almost never means the pan is ruined. It means the protective layer just needs to be fixed!

And luckily, that’s pretty easy to do. You can have your pan working again in less than 30 minutes!

Why Does Cast Iron Rust?

A cast iron pan starts as bare metal. As you cook with is, oils polymerize and the surface of the pan is built up with layers of nonstick seasoning. Your seasoning layer is the only thing standing between “useful cooking surface” and “dangerous rusty metal.”

When that layer gets compromised, rust can start to pop up. Here are the most common reasons a cast iron pan rusts:

It stayed wet.

The most prevalent cause of rust. Air-drying your pan in the dish rack, setting it in the sink, or putting it into the cabinet damp is enough for rust to form.

The seasoning wore out.

Seasoning isn’t permanent. Scrubbing the pan too harshly, cooking acidic food, or long stretches of heavy use can expose small areas of bare metal.

It sat unused.

A pan stored for months in a humid cabinet will eventually start to rust, even if it was clean and dry when you put it away.

Someone soaked it.

Or worse, someone put it in the dishwasher. Dishwashers are a big NO for cast iron.

How to Fix It Quickly

You don’t need to fully restore the pan unless the rust is extensive. Most cases require a straightforward cleanup and re-season. Here’s what to do to save your pan:

1. Remove the rust

Use steel wool, a stiff brush, or coarse salt and a paper towel.
Scrub until the orange rust is gone and you’re back to bare metal.

This is not delicate work. You’re not polishing a diamond, you’re removing oxidation. Don’t be afraid to scrub hard.

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2. Wash and dry immediately

Rinse with warm water and a little dish soap. Yes, soap is fine.

Dry with a towel, then put the pan on a burner over medium heat for a minute or two to evaporate any remaining moisture. Skipping this step is how people end up back at the beginning.

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3. Apply a thin layer of oil

Add a small amount of oil and rub it over the entire surface. Then wipe it off with a soft cloth until only a very thin layer is left.

You truly want a microscopic layer. If it looks shiny or wet, there’s still too much oil.

Heat the pan until it just starts to smoke lightly, then let it cool. That’s enough to protect the metal and get you cooking again.

When Do You Need a Full Re-Season?

Do a full oven seasoning if:

• Rust covered most of the surface
• You had to scrub aggressively
• The pan feels rough or patchy afterward

Otherwise, the quick fix is sufficient. Cast iron doesn’t require a freak out every time something goes wrong.

How to Keep It From Happening Again

Rust is mostly a drying problem. Be careful of any moisture that remains when you put your pan into storage.

After washing:

• Dry the pan with a towel
• Put it on heat for a minute or two
• Optionally wipe a tiny bit of oil on before storing

That’s alone will prevent nearly all instances of rust. When you use your cast iron, wash and dry it thoroughly. Neglect and moisture are what cause problems.

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Is Rust Actually a Big Deal?

Not really.

Rust looks alarming, but it’s one of the easiest cast iron problems to fix. Sticky seasoning, flaking buildup, and rancid oil are usually more annoying.

If your pan rusted, you didn’t ruin it. You exposed the metal. Then you removed the rust. Now you keep cooking!

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If You’re Seeing Rust, You Might Also Be Dealing With…

• Sticky seasoning
• Food suddenly sticking
• A pan that smells faintly off
• Uneven or patchy seasoning

These are all related. Once the protective layer gets compromised, small issues tend to cluster.