How do I look after a cast iron pan?

Seasoning is polymerised oil bonded to the iron, not a fragile coating of grease. Modern washing-up liquid won't remove it — that myth dates from when detergents contained lye. What does damage cast iron is water: soaking it, or leaving it wet, both cause rust.

What you'll need

• Stiff brush or chainmail scrubber
• Kitchen paper
• Neutral oil
• Coarse salt for stubborn residue (optional)

Step by step

1. Clean the pan while it's still warm.Residue lifts far more easily from a warm pan than a cold one.
2. Use hot water and a brush; a little washing-up liquid is fine.The 'never use soap' rule dates from lye-based soaps. Modern detergent won't strip polymerised seasoning.
3. For stuck-on residue, scrub with coarse salt and a little oil.Abrasive enough to clear it without stripping the seasoning.
4. Never soak the pan or put it in the dishwasher.Prolonged water contact is what causes rust and can lift the seasoning.
5. Dry immediately and thoroughly, then put it on a low heat for a minute.The heat drives off water from the pores. This is the step that prevents rust.
6. Wipe a very thin film of oil over the cooking surface while warm.Thin — buff it as though trying to remove it. Excess oil goes sticky and rancid.
7. Store somewhere dry, with a piece of paper towel inside if you stack pans.Trapped moisture between stacked pans is a common cause of rust.
8. To rescue a rusty pan, scour the rust off, wash, dry, then re-season in the oven.Thin oil coat, upside down at around 220°C for an hour, and repeat a few times to build the layer.

Tips

• Cooking with it is the best way to maintain seasoning — frying and anything with fat builds the layer up naturally.
• Avoid long-simmered acidic dishes like tomato sauce in a lightly seasoned pan; the acid can strip seasoning and give a metallic taste. A well-established pan handles it fine.
• Cast iron holds heat superbly and heats unevenly. Preheat it slowly and give it longer than you think.
• A chainmail scrubber is the single most useful cast iron accessory — it cleans effectively without damaging the seasoning.

Common mistakes

• Soaking the pan — Prolonged water contact causes rust, sometimes within hours.
• Putting it away damp — The most common cause of a rusty cast iron pan.
• Applying too much oil when seasoning — Excess oil polymerises unevenly into a sticky, tacky surface.
• Avoiding detergent entirely — The rule is outdated, and it leads to pans that are genuinely not clean.

Questions people ask