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How to Tell When Your Cast Iron Skillet Is Hot Enough

Most of us remember our mothers and grandmothers using a cast iron skillet for cooking. Except for smelly fish, you can prepare anything with success in a cast iron skillet.

Nevertheless, when non-stick and, in the last decade or so, ceramic pans came on the cooking scene and made cooking non-stick, cast iron skillets became a lesser common choice of cookware for home cooks.

Those of you who are just getting into cooking with cast iron may wonder how to know when your cast iron skillet is hot enough. Here are some tips about cast iron cooking that will make you an expert in no time.

A cast iron skillet doesn’t heat as quickly as a stainless steel or non-stick pan, but it does so evenly and holds on to that heat very well.

Preheat the cast iron skillet on medium to medium-high heat for 4-5 minutes, until evenly heated. To tell when it’s hot, carefully move your hand over the bottom of the pan. When you can feel it radiating heat, that’s a tell-tale sign it’s ready to cook in.

Be very careful with this method when there’s butter or oil in the skillet, as it could splatter and burn your hand. Instead, observe the fat’s or oil’s movement: when it starts dancing in your pan, it’s probably ready.

Preheating, necessary for searing steak, is almost always recommended when you’re using your cast iron skillet on the stove.

A cast iron pan is essentially indestructible. As long as you keep yours well-seasoned and avoid dropping it from heights (believe it or not, they’re prone to breaking into pieces), it can last you a lifetime.

If you experience food accumulating a black residue along the edges, it’s because of insufficient seasoning. Correct measures must be taken to re-season the pan to keep this from happening as you cook.

Seasoning a Cast Iron Skillet

Seasoning makes your skillet release foods easily, clean up quickly and stay rust- and stain-free. Some cast iron skillets on the market come pre-seasoned.

As a result, they have a smooth, non-greasy, softly lacquered surface that you can cook with as soon as you’ve finished unpacking them. Of course, if your cast iron skillet didn’t come pre-seasoned, you can just as well season it yourself (see how below).

Scrub the skillet in soapy hot water, then pat it completely dry using a paper towel. Spread a very thin coating of vegetable oil over the entire skillet (interior and exterior).

Place it upside down on a middle oven rack at 375°F, placing foil or a baking sheet on the lower rack to catch any drips. This method adds a thorough layer of seasoning over the entire pan, strengthening the bond to the iron.

Bake for one hour, then let it cool for about as much in the oven. As soon as it’s not too hot to touch, you can get cooking with it!

YouTuber Joshua Weissman shows you exactly how to do this in the clip below:

Generally speaking, all cooking fats and oils can be used to season cast iron. However, avoid using butter or olive oil—they’re great to cook with, just not for the initial seasoning. For a seasoning bonus, cook bacon, a steak, or thick pork chops in the pan for its initial use.

Cast iron seasoning works best when using very thin layers of polymerized oil from unsaturated fats like corn oil. The saturated fats found in melted shortening or lard don’t polymerize as well. 

Canola oil has a high smoke point of 400°F, while virgin olive oil begins smoking between 325-375°F. So seasoning with olive oil will work, but it may get smoky.

Remember that the seasoning of cast iron is an ongoing process: every time you cook using in the pan, it helps to season it a little more.

With a dry sponge or cloth, spread a layer of oil around both the inside and outside of the cast iron skillet after each use to ensure quality cooking every time. 

Cleaning Your Cast Iron Skillet

Clean the skillet immediately after each use. Soap is made to remove oil and will damage the seasoning, which gives cast iron its non-stick properties. Don’t soak the pan in water because it may rust.

You must allow it to cool down entirely before immersing it in water. Using hot water, wash the skillet by hand using a sponge or stiff brush. Don’t forget to dry the surface immediately after washing to prevent it from rusting.

What Not to Cook in Cast Iron Pans

Some foods should not be prepared in a cast iron skillet.

Avoid cooking acidic sauces, such as tomato-based pasta sauces, in cast-iron skillets because the acid will loosen trace amounts of molecules from the pan that can get in your foods, causing a metallic taste. While perfectly safe to eat, these metallic flavors are unpleasant.

Another reason is that acid causes the seasoning on a cast-iron pan to break down. Remember, the seasoned coating on a cast-iron skillet is the layer of polymerized fat that naturally makes the pan non-stick. 

To preserve your cast-iron pan, avoid cooking acidic foods in it for more than a few minutes. Just finishing pan-fried chicken breasts with a spritz of lemon juice. That should be fine. But if you’re making a slow-simmered Sunday pasta sauce or Bolognese, use an enamel-lined Dutch oven rather than your cast iron skillet.

Cast-Iron Surface Absorbs Smells and Flavors

When never used and not been through several rounds of seasoning, a cast-iron pan has a porous surface that will absorb the flavor of foods cooked in it.

Even a well-seasoned pan is more apt to take on flavor than a stainless steel or non-stick pan, which is why cleaning a cast iron skillet with soap can strip the seasoning.

For this reason, think twice about making that skillet cookie directly after the salmon from last night’s dinner. If you plan on using your cast iron skillet for making desserts, it might be wise to buy a separate skillet for them. After all, cast-iron skillets are inexpensive.

Avoid Preparing Sticky Foods Until the Skillet Is Well-Seasoned

For the first two months, or longer if it isn’t used often, you should avoid cooking foods prone to sticking.

For example, scrambled eggs, an omelet, fried rice, and pancakes are all foods that might cook well on a shiny, extremely well-seasoned pan. However, they will stick to a new pan that hasn’t been used much.

Not only will you over-cook your eggs and have weirdly shaped pancakes, but you may need to scrub—and, possibly, soap—the skillet to get it clean again, stripping away the pan’s seasoning.

Remember that cast iron maintains heat. So once a cast-iron pan is hot, it will stay hot. This makes cast iron the perfect material for higher-heat applications like searing a steak—and better browning means a more delicious steak.