How to season cast iron and keep it seasoned

What is cast iron seasoning?

Seasoning is a layer of oil that has been baked onto the surface of the pan. The manufacturer Lodge explains that when oils or fats are heated in cast iron at a high enough temperature, they change from a wet liquid into a slick, hardened surface through a process called polymerization, and that layer bonds to the iron. A Virginia Tech food scientist, Sean O'Keefe, describes the result as a thin protective layer that keeps the pan from rusting and gives it its nonstick properties. Bare cast iron rusts quickly, so the seasoning is what protects it.

Some pans come pre-seasoned, and Lodge, for example, seasons its cookware at the foundry, so a new Lodge pan can be rinsed, dried, and used right away. You also add seasoning every time you cook with oil or fat, and Lodge notes that the first layers built through cooking may look patchy or uneven before they fill in with regular use. Oven seasoning is the tool for a pan that has lost its finish, turned rusty, or needs a stronger base, and you can repeat it whenever you want to build up additional layers.

Which oil should you use to season cast iron?

Lodge recommends a neutral oil with a high smoke point for seasoning at home, and says its test kitchen often uses vegetable or canola oil. The company seasons its own cookware at the foundry with a thin layer of soy-based vegetable oil. O'Keefe at Virginia Tech suggests an oil with a high polyunsaturated content that can form a firm layer, such as soybean or flaxseed oil, and notes that coconut oil would not work as well.

Lodge does not recommend beef tallow, lard, or ghee for seasoning because they can go rancid, although it says cooking with those fats is fine as long as you wash, dry, and oil the pan afterward. For everyday cooking, Lodge suggests adding a little oil to the cooking surface before you add food and keeping the cooking temperature below the smoke point of the oil you choose. Lodge, Virginia Tech, and University of Illinois Extension all describe a thin layer of oil, and Lodge names excess oil as the cause of a sticky finish.

How to season cast iron in the oven

These steps follow the manufacturer Lodge's instructions for reseasoning. Check the care guide for your own pan before you start, since other makers may give different directions.

1. Wash the pan in warm, soapy water, then dry it completely with a paper towel or a lint-free cloth.
2. Rub a very thin layer of cooking oil over the whole pan, inside and out, with a cloth or lint-free paper towel. Lodge says the layer should be thin enough that it does not drip or run when you tilt the pan.
3. Preheat the oven to 450 to 500°F and place a sheet of aluminum foil on the bottom rack to catch any drips.
4. Set the pan upside down on the center rack so oil does not pool on the cooking surface, and bake it for 1 hour.
5. Turn off the oven and let the pan cool inside, which Lodge says allows the seasoning to adhere further to the iron.

O'Keefe recommends repeating the oil and bake cycle two to three times when you season a pan thoroughly before its first use.

How do you clean cast iron after cooking?

Lodge describes daily cleaning in three steps: wash the pan in warm, soapy water with a stiff-bristled brush or scrubbing pad, dry it completely with a paper towel or lint-free cloth, and then spread a thin layer of oil over the entire surface with a paper towel. For stuck-on food, the company suggests a nylon scrubbing brush or a pan scraper and a rinse under warm water.

You can wash cast iron with modern dish soap, since Lodge says today's dish soap is no longer strong enough to remove seasoning, and O'Keefe explains that the old warning against soap dates from a time when soap contained lye, while a polymerized layer does not wash off with modern soap. Both sources warn against the dishwasher, and Lodge says a dishwasher will remove the seasoning and likely cause rust. Lodge also advises against soaking the pan in water and saves steel wool and metal scrubbers for rust removal instead of daily cleanup. For more routines like this one, browse our cleaning and maintenance guides.

How do you keep cast iron seasoned between uses?

Lodge considers regular cooking the easiest way to maintain seasoning, since each time you cook with oil or fat you add another layer to the pan. Over time, those layers build up into a strong cooking surface. O'Keefe adds that a properly seasoned pan generally needs only to have food crumbs washed out and a wipe of oil after each use to keep the layer intact.

Preheating the pan before you add food also helps, because iron heats unevenly and O'Keefe advises making sure the whole surface is hot. Wooden utensils are ideal, and he says metal ones are fine as long as you do not dig into the surface. Store the pan completely dry, since Lodge lists moisture-prone storage among the common causes of rust, and keep it away from damp spots when you plan your kitchen organization.

How do you remove rust from cast iron?

Lodge lists four common causes of rust: leaving the pan to soak in the sink, putting it in the dishwasher, letting it air dry, and storing it in a moisture-prone place. Lodge's process for fixing it at home starts with scouring the rusty areas with steel wool or a metal scrubbing pad and washing the pan in warm, soapy water, which may remove some of the seasoning as well, and then rinsing and drying the pan completely.

For small amounts of rust, Lodge says applying a very thin, even layer of cooking oil inside and out may be enough, and you can go back to cooking. When the rust is more extensive and a lot of seasoning has come off, follow the oven steps above: a thin coat of oil, 1 hour upside down at 450 to 500°F, and cooling in the oven. University of Illinois Extension gives the same basic advice to scrub the rust, clean and dry the pan well, and re-season it, and adds that any moisture left on the pan may cause it to rust again.

How do you fix sticky, flaking, or dull seasoning?

A sticky or gummy surface is a sign of excess oil. Lodge says it happens when too much oil is used or the pan is not heated long enough, and the fix is to bake the pan upside down for another hour at 450 to 500°F until the stickiness is gone. Black flakes are carbonized bits of oil from seasoning that has broken down, and Lodge states that they are not harmful; cooking usually resolves them, or you can wash, dry, oil, and bake the pan for an hour. Uneven color is normal and, according to Lodge, will not affect how the pan performs, and when a pan looks dull the company suggests sautéing vegetables to build seasoning or reseasoning it in the oven.

Acidic foods call for some care, and University of Illinois Extension notes that acidic, high-moisture foods such as tomatoes absorb the most iron from the pan and that the acid breaks down seasoning, so the pan needs re-seasoning more often. O'Keefe says a properly seasoned pan can be used with acidic foods, though it is a poor choice for long simmers such as tomato sauce. Find more ideas for your pan in our kitchen and recipe section.