Cast-iron skillets, griddles, and Dutch ovens are versatile and durable. But over time, they can become sticky and hard to cook in as a layer of carbon and hardened food residue builds up, sometimes concealing a layer of rust firmly anchored to the cast iron below. That last point is important. Cast iron is a reactive metal, and water introduced in cooking and cleaning will attach to the iron. The rust is rough and porous; it forms an attractive surface for food residue and hardened oil. The result is cookware that’s a nuisance to work with.
Fortunately, the fix is simple. Sand off the crust and season the pan with high-temperature cooking oil. In doing so, you’ll convert the sticky, crusty surface to one that is beautiful, glossy, and nonstick.
Seasoning is nothing more than producing a baked-on layer of polymerized cooking oil on the pan’s surface. According to cookbook author and our grill consultant, Dave Joachim, seasoning is simple: Apply a thin layer of oil and heat it above its smoke point (usually between 350 and 450 degrees) for up to an hour to vaporize lighter hydrocarbons. This leaves heavier molecules to form a polymer (actually, a simple form of plastic) on the iron. Season a pan every time after you cook.
It’s important to draw a distinction between routine seasoning and the multistep restoration process that we show here. I used the four easy-to-follow steps shown below to sand clean and season two pans from Lodge Cast Iron: a 60-year-old skillet I inherited from my mom and a 14-year-old griddle. Both needed a seasoning overhaul.
Before you get started, you’ll need to gather up (or purchase) a few essential items. If you’re missing something on this list, check out our four recommendations below to help you fill in the gaps.
What You’ll Need• An old towel or nonslip rubber mat, a clean cloth or kitchen towel, lint-free cloths• Safety glasses, dust mask, hand cleaner, leather gloves• A random-orbit sander• 80-, 100-, and 120-grit sandpaper discs (60, as well, if your pan is too far gone)• High-heat seasoning oil, such as flaxseed
Step 1: Sand
Wash the pan with water and dish detergent, and dry it to remove the thin film of surface grease. Place the pan on an old towel or nonslip rubber mat. With a random-orbit sander, make thorough passes over the surface using 80-, 100-, and 120-grit sandpaper discs. (Note: If the pan is rusty or has severe black scale on its surface, you may need to start with 60-grit.) Sand thoroughly with each grit, beginning with the lowest-number (or coarsest) grit and working up. It will probably require more than one disc of each grit to complete the sanding at that level before moving to the next.
Tip: Sanding cast iron is dirty work. Wear safety glasses, a dust mask, and old clothing. Clean the work area thoroughly when you are done and vacuum the sander clean. You’ll need hand cleaner to get the carbon and rust off your hands. Put your work clothing into the wash immediately.
Step 2: Prepare
Preheat the oven to a temperature equal to the smoke point of the oil you are using, which is typically in the range of 350 to 450 degrees. While the oven is warming up, prepare the pan. Remove metal particles and carbon dust. Thoroughly wipe it down inside and out with a clean, lint-free cloth, soaked with the same oil you will use for seasoning (flaxseed oil is a good choice). Rinse the pan, dry it, then place it on a stove-top burner on medium-high heat, and bring it up to seasoning temperature. How long that will take depends on the burner’s BTU output and the size of the pan. A large and deep skillet may take 15 or 20 minutes to heat; a small griddle may take 10 minutes.
Tip: The oil’s smoke point may be listed on the bottle’s label. If not, a simple Google search should get you the answer you need. Flaxseed oil, for example, has a smoke point of 450 degrees.
Step 3: Seasoning on the Stove Top and in the Oven
Rotate the pan on the stove top as it heats to ensure it’s evenly heated. When the pan is hot, but not smoking hot, pour about a teaspoon of the high-temperature seasoning oil into the pan and carefully spread it over the pan’s inner surface, rim, and its outside—which should also be nonstick. Wipe with a clean, lint-free cloth. Turn the burner off. Wipe the pan dry with a separate clean cloth until there is no more than a faint sheen of oil.
While the pan is still hot, place it in the preheated oven—top side up—and leave it there for an hour. After an hour, turn the heat off and let the oven and pan cool to room temperature before removing the pan (about another hour or so).
Repeat this entire process of stove-top seasoning followed by oven seasoning as many times as necessary to produce a glossy, nonstick surface. It will probably require at least three or four trips over the stove top and into the oven before you’re done (each trip over the burner and into the oven counts as one seasoning pass). It’s a good idea to alternate the pan’s position—top side up the first trip, bottom side up the next—every trip into the oven. Switch to top side up on the third pass and then bottom side up for the fourth pass. This ensures uniformly seasoned cookware with a nonstick surface on its inside and outside.
Tip: Wear leather gloves when wiping out a hot pan. It’s easy to give yourself a burn, especially on deep pans when you wipe the rim. Also, if your oven’s temperature is above the oil’s smoke point, the heat will produce carbon, blackening the pan. Some purists insist on producing a glossy black finish and theorize that the formation of carbon produces a tougher seasoned surface. We stopped the seasoning process after four trips over and through the oven, producing dark gray-bronze pans in the process. Neither is glossy black. The pans cook like a champ and we’ll let them blacken over time.
Step 4: Ready to Cook
This might be overly cautious, but after putting all that work into the overhaul process, I make sure to apply a layer of high-temperature oil to the pan’s inside the first time I cook with it. I heat the pan to cooking temperature, give the inside a light coating of oil, thoroughly wipe off any excess, and begin cooking with whatever oil or fat the recipe calls for (olive oil, butter, bacon fat). Overkill? Perhaps. I haven’t found it necessary to do this every time I cook. If anything, cooking and routine seasoning improve the pan’s performance.
Immediately after cooking, turn off the burner, wipe the pan out, pour in some hot water, and let it steam while you eat. After the meal, pour out the water and gently remove any slightly stuck-on food. At this point, the pan is clean but not reseasoned. Reheat the pan, pour in a little high-temperature cooking oil, then carefully wipe off excess oil, leaving it with a slight sheen. Let the pan heat for a few minutes before turning off the heat, and wait for the cookware to cool before storing it.
Tip: After wiping the pan and rinsing it, I also like to pour hot water in it to steam clean it (I simply heat a Pyrex container of water in the microwave). Don’t use cold water, according to many cast-iron experts; the thermal shock might crack it.
