Your Setting Was Correct Five Minutes Ago

The short answer: preheat the empty pan on medium for five to ten minutes, add oil once it is hot, add food once the oil shimmers, and then turn the heat down. That last step is the one nobody mentions and it is the whole difference. Cast iron does not settle at the temperature you set it to: it keeps absorbing heat for as long as it sits on the burner, so a setting that was right at minute five is too high by minute ten. That single property explains almost everything people find confusing about it, including why one manufacturer says food sticks because the pan is too hot while another says maximum heat is what stops food sticking. Both are describing real behaviour at different moments.

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Two makers, opposite explanations, both correct

Ask why food sticks to cast iron and you get two answers from two cookware manufacturers, and they contradict each other completely.

One says the pan is too hot. Its position is direct: the most common reason food sticks to cast iron is simply that the pan is too hot, and because cast iron retains heat far better than other cookware, you generally do not need as high a setting as you would with stainless or aluminium. It adds that there is no need to go above medium.

The other says the pan is not hot enough. Its explanation is equally mechanical: when cast iron is ripping hot, the Maillard reaction happens almost instantly, fast browning means food releases before it has a chance to stick, and high heat firms up proteins in eggs and meat rapidly, so there is less time spent in a loose tacky state.

Both of those are true. They describe different moments.

The sentence that reconciles them

It is buried in the same manufacturer’s advice about preheating, and it is the most useful thing on this subject: after you preheat the pan, you may need to reduce the temperature slightly, because cast iron will continue to absorb heat as it sits on the burner.

Read that again. The pan does not reach the temperature you set and stay there. It carries on climbing.

Every other pan in your kitchen finds an equilibrium: a stainless or non-stick pan on medium settles at a medium temperature and holds. Cast iron is a large thermal mass on a heat source, so it keeps taking on energy for as long as the burner is on, and by minute ten it is hotter than it was at minute five with the dial untouched.

So the pan needs to be very hot when the food goes in, and cooler than that a few minutes later. Both manufacturers are right, and the instruction that joins them is to turn the heat down after preheating.

Which explains the things that make no sense otherwise

Why a steak sears beautifully and the eggs ten minutes later burn on the same setting. Why pancakes are perfect at first and scorched by the third batch. Why the pan seems to behave differently depending on how long you have been cooking, which it does.

None of that is the seasoning and none of it is you. It is a pan that has been gaining heat the entire time.

All of which changes what the preheat is actually for.

Work out your heat in 3 taps

What you are cooking, what your hob is, and what went wrong last time. Those three decide the setting and the timing.

The sequence, and where the adjustment goes

Five steps, and the fifth is the one that separates cast iron from every other pan.

1. Preheat the empty pan on medium, on a similar-sized burner. Five to ten minutes. Matching the burner to the pan matters more here than with a thin pan, because cast iron conducts heat slowly and a small ring under a large skillet leaves the rim cold.
2. Check it is evenly hot before the oil goes in. Hover a hand a few inches above the base and move it out toward the rim; you are feeling for whether the edges have caught up. A few drops of water that sizzle and vanish immediately is the other test.
3. Add the oil, enough to coat the base. Not before this point, since oil left heating too long can pass its smoke point and start polymerising, which turns sticky. Foods prone to sticking such as eggs want more; fatty foods such as chicken thighs want less.
4. Add food when the oil shimmers. That is the signal. Too cold and the food absorbs the oil rather than searing in it; smoking means the pan is too hot and wants a minute off the burner.
5. Then turn the heat down. This is the step. The pan keeps absorbing heat from the burner throughout, so the setting that was right for the preheat is too high for the cooking.

Butter, and the order it goes in

Butter burns well below the temperature a preheated cast iron pan sits at, which is why it browns and catches in seconds. The manufacturer’s own workaround is neat: start with oil, then add the butter right before the food goes in.

The oil protects the surface and takes the heat; the butter arrives late enough to flavour without burning. It is the same reason a restaurant finishes a steak with butter rather than starting with it.

And leave the food alone

The instinct when something sticks is to move it, and moving it is what tears it. Food releases from cast iron when the crust has formed, not before, and prodding it interrupts exactly the process that would have freed it.

Wait for the crust to appear around the edge of whatever you are searing, and it will lift cleanly. If it genuinely will not release after that, the pan was not hot enough when it went in.

Hot spots, and what to do about them

Cast iron holds heat superbly and conducts it slowly, and those two properties pull against each other. The consequence is a pan that is hotter in the middle than at the edges for longer than you would expect.

Finding them

The butter test is the simplest: drop a knob onto the preheated base and watch where it melts first and fastest. The egg test works the same way, since an egg spreads and sets unevenly over an uneven surface.

An infrared thermometer does it properly, and this is the one kitchen job where it earns its place, because you can read the centre and then the rim and see the gap in degrees rather than guessing.

Working around them

Spread food out and give each item room. Crowding leads to steaming rather than searing and overwhelms even a properly preheated pan.

Stir and flip strategically, which redistributes heat and stops any one spot overcooking. It matters most with vegetables, diced meat and anything prone to sticking.

Use a lid. Trapping steam balances the heat across the whole pan, which is particularly useful for thick cuts and anything moisture-heavy such as a braise or a hash.

Pat ingredients dry. Wet ingredients create steam bursts that disrupt browning, and recently washed produce or marinated meat is the usual culprit.

What not to cook in it, and the one real limit

Cast iron takes any hob, the oven, a grill and an open flame, and can sear, sauté, bake, broil, braise, fry and grill. The list of things it does badly is short and it is mostly one thing.

The two bottom rows are the same rule stated twice. Liquid strips seasoning and acid accelerates it, so a long simmer of something acidic is the combination that takes a pan back noticeably in one meal.

That is not a prohibition. It is a reason to keep long tomato sauces off a pan whose patina is still building, and to wash and re-oil promptly when you do cook one.

The one that shows you what the pan is doing

Reads surfaces from -58°F to 1112°F. Non-contact, instant.

The whole difficulty with cast iron is that it keeps gaining heat and looks exactly the same doing it. A thermometer turns that invisible drift into a number, and after a week of pointing it at the pan you stop needing it, because you have learned what your own hob does at each setting.

The range matters here. Searing temperatures go well past the ceiling of a cheaper model, and a thermometer that tops out too low simply reads maximum and tells you nothing at exactly the moment you wanted to know. Eleven hundred degrees covers everything a domestic hob can produce.

It is also the only practical way to find hot spots. Read the centre, then the rim, then the far edge, and the gap between those numbers tells you whether to rotate the pan, move to a bigger burner or simply preheat for longer. That is a question nobody can answer by hovering a hand.

Worth it or skip: Worth it if you have burned a second batch of something on a setting that worked for the first, which is the specific problem it solves. Skip it if you cook on cast iron occasionally and are happy to preheat generously and turn the heat down by feel.

Check the infrared thermometer on Amazon

Three more, by what you are missing

A thermometer with adjustable emissivity and a probe included. Emissivity is the specification that decides whether a surface reading is accurate, since dark matte cast iron radiates differently from shiny stainless, and a model you can adjust reads both correctly. This one also includes a probe thermometer for internal temperatures, which is the other half of cooking a steak properly: the surface tells you about the crust and the probe tells you whether the middle is done. See the adjustable emissivity version →

A 12 inch skillet with a tempered glass lid, if you are starting from nothing. Twelve inches suits most households and the lid is what makes the pan good at the wet jobs: trapping steam balances heat across the surface, which is the practical answer to hot spots on a braise. Glass means you can watch without lifting. It is pre-seasoned, so it works from the first use, and the lid is rated to 400°F, which covers simmering and not searing. See the 12 inch skillet with lid →

A lid on its own, if you already have the pan. Fits 10 to 10.25 inch skillets. Most cast iron is sold without one and a lid changes what the pan can do: braises, steamed vegetables and anything where you want to hold moisture rather than drive it off. The detail worth noting is that its steam vent doubles as a thermometer port, so a probe goes in without lifting the lid. Check your pan’s measurement before ordering, since these are sized to specific models. See the glass lid →

If food is sticking and the heat is right, the surface is the next thing to look at, and the hob can rebuild it in fifteen minutes. I go through it in the burner can only reach half the pan.

The last meal went wrong? 2 taps

The quiz above is for planning the heat. This one starts from what happened, and the second question usually names the cause.

People also ask about cooking with cast iron

How do you cook with a cast iron skillet?

Preheat the empty pan on medium for five to ten minutes on a burner that roughly matches its size, add oil once the pan is hot, add food once the oil shimmers, and then turn the heat down. That last step is the one most instructions leave out, and it matters because cast iron keeps absorbing heat as it sits on the burner rather than settling at the temperature you set. Leave the food alone while it sears, since it releases when the crust has formed rather than when you prod it, and remember that the handle is exactly as hot as the pan.

Why does food stick to my cast iron pan?

Two opposite causes, which is why the advice online contradicts itself. One manufacturer says the commonest reason is that the pan is simply too hot, since cast iron retains heat so well that you rarely need more than medium. Another says the opposite, that at high heat browning happens almost instantly and food releases before it can bond. Both are describing real behaviour: an underheated pan lets food sink into the surface, and an overheated one scorches it on. The tell is what is left behind, since scorching leaves dark residue while an underheated pan leaves a pale sticky film. Also check you used enough oil, since foods prone to sticking need more than fatty ones.

How long should you preheat cast iron?

Five to ten minutes on medium, and the published range runs from four to at least ten because it depends on the pan’s thickness, its size against the burner and how cold it started. Longer and gentler is better than shorter and hotter, because what you are waiting for is the heat to reach the rim rather than the centre to get hot. Test it by hovering a hand a few inches above the base and moving outward, or by flicking in a few drops of water, which should sizzle and vanish immediately. Do not preheat the oil with the pan: add it once the pan is hot, or it can pass its smoke point and start to polymerise.

What should you not cook in cast iron?

Long simmers, and acidic ones most of all. Liquid is what strips seasoning fastest and acid accelerates it, so a tomato sauce cooked down over an hour will take a young pan back noticeably in one meal. A short acidic cook on an established pan is fine. Delicate white fish is the other awkward case, since it sticks readily and wants a properly mature patina. Everything else is fair game: cast iron sears, sautés, bakes, broils, braises, fries and grills, and works on any hob, in an oven, on a grill and over an open flame.

Cast iron cooking FAQ

Can I use butter?

Yes, and not first. Butter burns well below the temperature a preheated cast iron pan sits at, so it catches within seconds. The manufacturer’s own workaround is to start with oil and add the butter just before the food goes in, which is the same order a restaurant uses when finishing a steak. The oil takes the heat and the butter arrives late enough to flavour rather than burn.

Can I use metal utensils?

On an established pan, yes, and the worry is misplaced. A polymerised seasoning layer is bonded to the metal rather than sitting on top of it, and a metal spatula scraping food off is doing what it was designed for. What actually damages seasoning is acid and prolonged liquid. On a very young pan go gently until the layer has built up.

Why did my food steam instead of browning?

Moisture, from one of two places. A crowded pan traps the steam each piece releases and drops the temperature below the point where it can evaporate, so give everything room and cook in batches. Or the ingredients were wet: recently washed produce and marinated meat carry more surface liquid than they look like they do, and it creates steam bursts that disrupt browning. Pat things dry before they go in.

How do I find hot spots?

Drop a knob of butter onto the preheated base and watch where it melts first and fastest, or fry an egg and see where it sets unevenly. An infrared thermometer does it properly, since you can read the centre and then the rim and see the gap in degrees. Then either rotate the pan while cooking, move to a burner that matches its size, or use a lid, since trapping steam balances heat across the surface.

Can I put a glass lid on it?

For wet cooking, yes; for searing, no. Tempered glass lids are typically rated to 350 or 400°F, which covers braising, simmering and steaming comfortably and does not cover a hard sear, where a cast iron pan goes well past that. Use a glass lid for the jobs where you want to see what is happening, and take it off before the heat goes up.

Is cast iron really non-stick?

It becomes slick rather than non-stick, and it improves with every use, because cooking with oil deposits and polymerises more seasoning. A mature pan will fry an egg that slides freely. A new one will not, and that is not a fault in the pan or in you. Cook oily food over decent heat for a few weeks and the difference is obvious.

The cast iron cooking cheat sheet

Free printable

The Cozy Home Starter Checklist

A kitchen that works is mostly a handful of habits rather than a cupboard of equipment, and turning the heat down after the food goes in is exactly that kind of habit. This printable walks you through a home room by room, catching the ones worth keeping.

Get the free Cozy Home Starter Checklist

Keep reading

• The Burner Can Only Reach Half the Pan
  If food sticks and the heat is right, the surface is next, and the hob rebuilds it in fifteen minutes.
• Look at the Handle Before You Turn the Oven On
  The same polymerised layer on a curved pan, where two manufacturers give opposite instructions.
• The Board That Gets Safer With Age, and the One That Does Not
  The other kitchen surface that improves with use, where research found the hygiene assumption runs backwards.
• Name the Smell First. It Tells You Where to Look
  Four smells, four places, and the two minute test that decides whether to clean or call a plumber.
• Scandinavian Kitchen Design: Functional, Minimal, and Cozy
  Where tools that get used daily belong in a kitchen meant to be worked in rather than photographed.

Preheat, then turn it down

Almost everything people find difficult about cast iron comes from one property, and it is not the seasoning. The pan does not settle at the temperature you set it to. It keeps absorbing heat for as long as it sits on the burner, so the setting that produced a perfect sear at minute five is burning the eggs at minute ten with nothing touched.

That is why the manufacturers appear to contradict each other on why food sticks. One says the pan is too hot, the other says it is not hot enough, and both are describing genuine behaviour at different points in the same cook. The pan needs to be properly hot when the food goes in, so the crust forms fast and releases it, and cooler than that a few minutes later.

So the sequence is preheat empty for five to ten minutes, oil once the pan is hot, food once the oil shimmers, and then reduce the heat. Leave the food alone until it lets go on its own. Give everything room, because a crowded pan steams. And pat wet ingredients dry.

After a few weeks of that you stop thinking about any of it, because you have learned what your own hob does. Until then, the single most useful habit is reaching for the dial after the food goes in rather than before.