Seasoning is just oil baked past its smoke point until it bonds to the iron. Get three details right - a lint-free wipe, a genuinely thin layer, and a hot enough oven - and the pan does the rest.
Marcus Doyle
Seasoning is not a flavor and it is not a non-stick spray. It is fat that has been heated past its smoke point so it polymerizes - the molecules cross-link into a hard, plastic-like layer chemically bonded to the metal. Each round of seasoning adds a microscopically thin layer; a well-used pan has dozens of them.
This is why a new pan sticks and a ten-year-old pan does not. It is also why you cannot fix a sticky pan with one thick coat of oil: thick layers stay gummy because the oil underneath never fully polymerizes. Thin and repeated always beats thick and once.
Wash the pan with warm water and a small amount of dish soap - yes, soap is fine on cast iron - and scrub off any rust spots with a scouring pad. Dry it completely on a burner over low heat for two or three minutes. Water hiding in the pores will sabotage the seasoning.
Rub a small amount of oil over every surface: inside, outside, handle, the lot. Then take a clean, lint-free cloth or paper towel and wipe it off like you made a mistake. The pan should look dry with a faint sheen, not glossy. This wipe-it-all-off step is the single most important part, and it is the one people skip.
Place the pan upside down in a 230C / 450-500F oven, with foil or a tray on the rack below to catch any drips. Bake for one hour, then turn the oven off and let the pan cool inside. Repeat the oil-wipe-bake cycle two or three times for a new or freshly stripped pan.
Any neutral oil with a reasonably high smoke point works: grapeseed, canola, sunflower, or vegetable oil. Flaxseed oil briefly became internet-famous for seasoning, but its layers are prone to flaking off in sheets after a few months, so most experienced cast-iron users have gone back to ordinary canola or grapeseed.
Skip butter and olive oil for seasoning. Butter has milk solids that burn rather than polymerize, and extra-virgin olive oil smokes too early and tends to go sticky. They are fine for cooking in the pan later - just not for building the base coat.
Every time you cook with fat in the pan, you are micro-seasoning it. After washing, dry the pan on a low burner, then rub in a few drops of oil with a paper towel while it is still warm. That thirty-second habit does more for the pan than any annual deep-seasoning ritual.
Acidic foods - long-simmered tomato sauce, wine reductions, anything with vinegar - eat away at young seasoning. A well-established pan can handle a quick deglaze, but save the two-hour marinara for stainless or enameled cookware until your seasoning is several months old.
Light surface rust scrubs off with a scouring pad or a paste of coarse salt and oil. Once you are back to grey metal, dry the pan thoroughly and run two or three full oven-seasoning cycles. The pan is not ruined - cast iron is nearly impossible to ruin permanently.
Sticky or tacky patches mean too much oil in a previous round. Scrub the gummy area with a scouring pad, then re-season with a properly thin coat. For a pan with deep flaking or decades of crud, bake it through a self-cleaning oven cycle or use oven cleaner to strip it bare, then build fresh layers from zero.
Yes. Modern dish soap is mild and will not strip polymerized seasoning - that myth dates from when soap contained lye. What actually damages seasoning is soaking the pan in water or running it through a dishwasher.
Only when the pan looks dull, patchy, or starts sticking. A pan used regularly with the dry-and-oil-after-washing habit may never need a deliberate oven session again.
Either the oil layer is too thick or your oven is well above the oil's smoke point. Some smoke is normal and means polymerization is happening - run the exhaust fan. Billowing smoke means wipe more off next round.
It is usable but spartan - factory seasoning is one or two thin layers. Cook fatty foods like bacon or fried potatoes for the first several uses and avoid eggs and fish until the surface builds up.
