How To Season Cast Iron & What Is The Best Oil For Seasoning Cast Iron?

You can season your cast iron with the following steps:

If you’re a beginner, you will require more in-depth knowledge on how to season cast iron, so please keep reading this guide.

What is seasoning?

Phrases such as “seasoning the pan” or “seasoning a cast iron skillet” refer to coating your cookware with oil and baking it in an oven, thereby cross-linking and polymerizing the oil and cast iron molecules on the pans surface.

This forms a hard non-stick surface on the cast iron cookware which protects it from food and the rust.

The best oil for seasoning cast iron

The best oil for seasoning cast iron is flaxseed oil, it’s a drying oil which helps with strength, it contains a high amount of polyunsaturated and unsaturated fats, making the seasoning harder and it contains a high amount of omega-3 which also helps to create a harder seasoning.

All these factors combined make flaxseed oil the best oil for seasoning cast iron.

Flax seed oil for seasoning cast iron

If you don’t have flaxseed oil, then use the calculator below to find out the seasoning strength of your oil. The higher the oil score, the better.

If you would like to read more about the different cooking oils for seasoning, keep reading, otherwise skip to the seasoning guide.

Cold pressed vs unrefined vs refined

Cold pressed, unrefined and refined oils are all the different methods that manufactures use to create the oil. Pressed oils are created by mechanically pressing the seeds, unrefined oils are lightly filtered to only filter out the largest particles, and refined oils are heavily filtered and strained with heat to remove smaller particles.

All these methods for creating the oils affect the flavor of the oil, so it’s important to know when your using it as salad dressing, but when it comes to seasoning a pan most of the compounds will get burnt off anyway.

Unsaturated vs saturated fats

Saturated fats are a popular option for many, this includes bacon grease and lard. But the reality is, you should always pick unsaturated fats when seasoning your cast iron.

This is because unsaturated fats are far more reactive than saturated fats, and thus polymerize better when seasoning.

So why do so many people use saturated fats? During the 19th century, people used lard or bacon grease because it was more readily available. It will still create a protective layer on your cast iron, but it won’t be near as good as unsaturated fats. This is why flaxseed oil and vegetable oil are becoming much more popular.

Monounsaturated vs polyunsaturated

Now we have established that we should be aiming for unsaturated fats, should we be aiming for monounsaturated fats or polyunsaturated fats in our oil for seasoning cast iron?

Simply put, monounsaturated fats have one double bond, where polyunsaturated fats can have 2-6 double bonds.

The more double bonds an oil has, the more reactive it becomes meaning it creates a better seasoning for your cast iron cookware. So always opt for oils with more polyunsaturated fats. The higher the percentage the better.

Smoking point

The smoking point of an oil is the temperature at which the oil turns to smoke. Pretty simple right?

So why do you need to know this? Well seasoning a cast iron pan is all about polymerizing the fats. When fats reach their smoking point, they begin to form bonds and polymerize. These bonds stick into the imperfections of the cast iron pan, essentially forming a barrier to block food from entering these imperfections.

If a fat doesn’t reach it’s smoking point, it won’t polymerize and you won’t get a protective barrier on your pan. This will be obvious because the oil will wipe straight off the pan.

So when deciding on an oil, it’s critical to know it’s smoking point so you can heat your pan to the required temperature needed to polymerize the oil.

Let’s take a look at the different oils and their properties to help you decide which one you want to use.

Corn oil

Corn oil is mostly polyunsaturated with a percentage of 82.3%. This makes it a good choice in terms of seasoning a cast iron skillet.

54.7% – Polyunsaturated
27.6% – Monounsaturated
12.9% – Saturated

The smoking point of corn oil is 450 °F (232°C) . This is relatively high in comparison to other cooking oils.

Overall with it’s high smoking point requirement, it’s not the best choice, however if you don’t mind the heat required to reach this smoking point, then overall it’s a good choice of oil for seasoning a cast iron skillet due to it’s high amounts of unsaturated fat.

Avocado oil

Avocado oil is mostly monounsaturated with a percentage of 70.6%. This makes it a good choice for seasoning cast iron, but it’s far from the best.

13.5% – Polyunsaturated
70.6% – Monounsaturated
11.6% – Saturated

The smoking point of avocado oil is 250 °C (482 °F). This is relatively high in comparison to most oils, so if you don’t mind the heat required to reach this smoking point then you will find this oil is not a bad choice overall.

Canola oil

Canola oil is mostly monounsaturated with a percentage of 63.3%. This makes it a good choice for seasoning cast iron, but like avocado oil it’s far from the best.

28.1% – Polyunsaturated
63.3% – Monounsaturated
7.4% – Saturated

The smoking point of canola oil is 238 °C (460 °F) which is slightly lower than avocado oil. So as with avocado oil, if you have the heat required to reach it’s smoking point, then it’s not a bad choice, just not the best.

Grapeseed oil

Grapeseed oil is mostly polyunsaturated with a percentage of 74.7%. This makes it a good choice in terms of the properties required for seasoning cast iron, and in fact you will notice that grapeseed oil is becoming more popular amongst seasoned veterans in the industry.

74.7% – Polyunsaturated
14.3% – Monounsaturated
10.5% – Saturated

The smoke point of grapeseed oil is 216 °C (421 °F) and is one of the lowest of all oils we are looking at. This is due to it’s high amount of polyunsaturated fat, so if you don’t have much heat to work with, this could be a fantastic option for seasoning your cast iron skillet.

Olive oil

Olive oil is mostly monounsaturated with a percentage of 73.0%. This makes it a good choice of oil for seasoning cast iron.

10.3% – Polyunsaturated
73.0% – Monounsaturated
13.8% – Saturated

The smoke point of olive oil is 193 °C (380 °F) which is relatively low amongst most of the oils we have discussed. Overall, if producing enough heat is an issue for you, then this is a fantastic choice for seasoning a cast iron skillet.

Lard

Lard is extremely high in saturated fat with a whopping 39%. This means it’s not ideal for seasoning cast iron unlike the tradition suggests. 90% of other options are better than lard for seasoning.

11% – Polyunsaturated
45% – Monounsaturated
39% – Saturated

The smoke point of lard is 374 °F (190 °C) which as you can probably tell this is extremely low. This is one of the reasons lard was so popular in the old days for seasoning due to it’s availability and low smoke point.

But in todays world where you can get a variety of oils to choose from, lard is no where near the top of the list. I would recommend avoiding lard for seasoning cast iron cookware.

Vegetable shortening

Vegetable shortening is another popular choice which is unjustified. It’s relatively high in saturated fats and relatively low in polyunsaturated fats.

28% – polyunsaturated
41% – monounsaturated
25% – saturated

The smoke point is 360-410°F (180-210°C) which isn’t too high, but at the same time it’s not low.

Therefor unless I only had vegetable shortening in my home, I would not use this as a seasoning product for cast iron cookware.

Bacon grease

Bacon grease is the second most popular saturated fat for seasoning cast iron. But as with lard it’s only a myth that’s it’s even remotely good in comparison to the other fats. It’s 32% saturated fat which means it’s the third highest saturated fat type on this list. And that means it’s bad for seasoning cast iron.

11% – polyunsaturated
41% – monounsaturated
32% – saturated

The smoking point of bacon grease is 190 °C 374 °F which is relatively low, so it’s easy to polymerize into a seasoning. But due to it’s saturated fat content, it’s just not reactive enough in comparison to other oils. I never season my cast iron skillet with bacon grease.

Coconut oil

For those who wouldn’t believe it, yes coconut oil is a whopping 87% saturated fats. Don’t worry it’s still healthy, but it’s not good for bonding to cast iron which means you should always avoid this oil for seasoning cast iron.

1.8% – polyunsaturated
6% – monounsaturated
87% – saturated

The smoking point of coconut oil is 400 °F (204.4 °C) so it’s around the middle in comparison to other oils, but as mentioned above, this is probably one of the worst options for seasoning cast iron. So simply leave it out.

Flaxseed oil (drying oil)

As mentioned above, flax oil is a drying oil which makes it extremely beneficial for cast iron pan seasoning. Combined with it’s 68% polyunsaturated fats totalling 86% unsaturated fats, flax oil is the best oil for seasoning cast iron.

68%- polyunsaturated
18% – monounsaturated
9% – saturated

But what makes it even better is the extremely low heat needed for it to begin to polymerize. The smoke point of flax oil is 225°F (107.2 °C) which will not only make it extremely easy to season, but it will speed up the time needed to season too.

Overall this is the best oil for seasoning cast iron without a doubt, and anyone who tells you different does not know their chemistry.

Vegetable oil

Vegetable oil is a common oil is many households. With it being 81% unsaturated fat with 48% monounsaturated fats and 33% polyunsaturated fats, it’s definitely a good contender.

33% – polyunsaturated
48% – monounsaturated
14% – saturated

The smoke point of vegetable oil is 449.6°F (232 °C ) which is relatively high. So overall, if you can reach those temperatures with your heating appliances, then I wouldn’t dismiss vegetable oil as a seasoning oil at all. I would advise it if you don’t have anything better such as flax oil.

How to season cast iron cookware

Now we have covered which seasoning oil you need for your cast iron pans, it’s time to start seasoning.

Knowing how to season cast iron can seem complicated, but honestly it’s really simple and we will be keeping it simple.

One of the biggest mistakes people make when seasoning cast iron is they select the wrong oil, and that just leads to mediocre results. Choosing the best oil is the most important step.

So before we begin, we need to select the best oil for seasoning cast iron.

Step 1: Preheat your oven

The first and most important step, is to preheat your oven (If you are using a stovetop we will cover this later when needed)

Now to choose the temperature you need to look at the smoke point of the oil you are using and then heat the oven up higher than the smoke point. So if the smoke point is 400°F you need to preheat your oven to around 420°F.

This will allow the oils to polymerize properly. Don’t select 400°F exactly if your smoke point is 400°F simply because you will be depending on the oils smoke point being accurately measured.

Always go around 20°F higher than the oils smoke point.

After you have set your oven to preheat, let’s move onto cleaning your cast iron pan while the oven is preheating.

Step 2: Clean your cast iron pan thoroughly

The next step is to clean your cast iron cookware.

To do this you’ll need to use some kosher salt. Why? Because cast iron has thousands of miniature pores where dust, dirt and food can get trapped. So even if you have a new cast iron skillet, there may still be dirt trapped in the pores and kosher salt will act as an abrasive whilst washing out easily.

A bottle of kosher salt which is used for cleaning cast iron

So get some kosher salt, and rub it over the entire pan using a new soft cloth. You need to ensure you rub it everywhere including the handle and the back of the cast iron pan, because we will be seasoning all of it.

Using a cloth to rub in kosher salt into the cast iron

Whatever you do, do not use a paper towel for cleaning cast iron prior to seasoning because the fibers on the paper towel will get caught into the pores of the cast iron, which will block the oils from entering the pores.

If for some reason you don’t have any kosher salt, then some suitable alternative include steel wool or a skin scrub brush, basically something that’s durable and won’t break off into the cast iron easily.

After you are satisfied that you’ve give your cast iron cookware a good clean you need to rinse the salt off.

To do this, simply put your cast iron pan into the sink, and run the tap over it. Now take a sponge and use the non abrasive side to wipe the salt off the pan.

After, gently use some paper towels to dry the pan.

rinsing the cast iron pan under a kitchen tap

Step 3: Coat the entire surface with oil

Now your cast iron cookware is fully dry, we need to start the pan’s seasoning process. So get the oil you have chosen and pour a small amount onto the pans cooking surface.

A small amount of oil in a cast iron pan

Now take a clean soft cloth, and rub the oil everywhere ensuring your coating the entire pan. Make sure you only rub a thin layer of oil onto the pan so you avoid using excess oil. If you do use excess oil, you will end up with a sticky layer of seasoning after you have finished.

using a paper towel to rub in the flax seed oil for seasoning the cast iron

You are probably wondering how much is too much oil? Well a little trick I use is, if I have to think about whether I’ve used too much oil, then I have used too much. The cast iron pan should look dry once you’ve applied a thin layer of oil.

If you have accidently used too much during the initial seasoning process, then get a second cloth and start wiping the pan down to remove some.

Try not to worry too much about excess oil too much though, because I have another trick up my sleeve on the next step.

Step 4: Baking it in the oven

Now you have coated the entire pan in a thin layer of cooking oil, it’s time to bake it.

Your oven should now be preheated to above the smoke point temperature of the cooking oil applied. So place your cast iron frying pan in the oven upside down.

Remember how I said if you used excess oil not to worry? Well placing the cast iron frying pan upside down in the oven will allow any excess oil to drip off. Just make sure you place some aluminum foil or a tray underneath so your oven doesn’t get coated in oil.

a cast iron pan upside down in the oven as part of the seasoning process

It’s better if you don’t apply excess oil in the first place, but if you do this should prevent any excess oil from remaining.

The oil won’t drip off at first, but as it heats up the viscosity of the oil becomes lower, and it’s then starts to drip off.

Now close the oven door and leave it in for an hour. After an hour take it out of the oven and move to step 5.

Alternative step 4: Using the stove top

If you don’t have an oven for baking your cast iron pot or pan, then there’s no need to worry. You can achieve the exact same result with a stove top.

The only downside to a stove top, is you need to keep an eye on it as you would with cooking in the unlikely event of a fire. So it can be quite time consuming.

All you need to do is coat the cast iron pot in oil, place it on the stove top and heat the pan up until you see smoke coming off.

heating the cast iron pan up on the stove top

Keep it at the temperature until all the smoke has disappeared, your pan will now be seasoned and you can move onto the next step or reapplying the seasoning.

Step 5: Applying more layers

At this point, you should now have a successful layer of seasoning on your cast iron. Your cast iron will feel smoother than it did previously due to the protective plastic like barrier.

Now you need to repeat the process again, applying a thin layer of oil and baking the cast iron frying pan upside down for an hour.

This will add more layers of seasoning onto your cast iron cookware, which reinforces the protectiveness of the seasoning.

You will need to repeat this around 6-8 times. I always aim for 8 if time allows, but if not then 6 layers is fine.

After finishing, you should now have a seasoned pan ready to use for cooking with a brilliant nonstick surface.


FAQ


Can you cook acidic foods in the pan?

You can cook some acidic food in the pan, but you have to be careful because any acidic food will eat away at the seasoning. If you cook acidic food too much in your cast iron pans without reinforcing the seasoning, you’ll eventually end up with no seasoning left.

How often do you season a cast iron skillet?

Once you have done the initial seasoning, you shouldn’t need to season it again. Simply because every time you cook, the fats from the food should add to the layer of seasoning, essentially reinforcing it with every meal you cook.

Can you cook tomato sauce in cast iron?

Yes you can cook tomato sauce in cast iron regardless of what other people say. Tomato sauce may be acidic, but as long as you have a good layer of seasoning on your pan, your cast iron will be protected from the acidic tomato sauce.

Can you ruin a cast iron pan?

You can ruin a cast iron pan very easily. Leaving it in water is one way to destroy it quickly. Always clean your cast iron pan thoroughly and make sure you dry it thoroughly after washing to avoid ruining it.

Can you soak cast iron?

As stated above, you cannot soak cast iron, this will lead to rust and destroy your cast iron cookware. If you need to clean it, use some soapy water with a scrub brush but don’t let it sit in water for a long time.

Can you absorb iron from a cast iron pan?

If it’s not seasoned yes, the iron will be absorbed by the food. This usually gives meat extra flavor, however if you have seasoned your cast iron then no iron will not be absorbed into your food due to the barrier the seasoning creates between the food and the cast iron.

Why is my cast iron seasoning sticky?

Cast iron seasoning can be sticky for multiple reasons, the most common being excess oil when seasoning it. If you use too much oil, some of it won’t have anywhere to bond and will turn into a sticky mess. Use a thin layer of oil when seasoning to avoid sticky seasoning.

How does seasoning protect cast iron?

The oils polymerize and bond with the pores in the cast iron, this creates a barrier on top of the cast iron, protecting it from both acidic products and moisture in the air. Just make sure you season the entire pan including the back and the handle to get full protection from seasoning.

Why you should care about seasoning your cast iron cookware

There are a variety reasons why you should want to season your cast iron cookware

First of all, seasoning a cast iron skillet gives it a nonstick surface. This is the main reason you want to season it. If you don’t have a non stick surface, you will end up with burnt food bonding to the surface making it impossible to clean. The nonstick layer also protects your pans from being scratched and damaged by utensils.

Second of all, the layers of seasoning create a barrier around the pan, this not only prevents rust and corrosion, but also helps decrease the amount of heat that is transferred to the food inside. Now you might be asking yourself how can a layer of seasoning make a difference in the amount of heat that gets transferred into food. That’s because this layer protects the food from being burned by hot pans surface during cooking.

Who should be seasoning cast iron?

Anyone can season their pans. There are no special requirements to seasoning you pan, and If you have just bought your first cast iron skillet and want to start using it right away for cooking, then seasoning it would be the best idea since you will be protecting it from rusting and avoid having food stick on its surface when cooking. Seasoning a pan before using it also prolongs its life.

Where Can You season cast iron?

Seasoning a cast iron skillet can be done anywhere at anytime. You can season your cast iron cookware at home and outdoors as long as you have some form of extreme heat such as an oven, a stove top or an outside grill.

How long does it take to season cast iron?

It depends on how many times your willing to season your pan. Each layer of seasoning should take around 1 hour and 15 minutes in total. 15 minutes to prepare the seasoning, and 1 hour baking time

You will also need to season your cast iron cookware multiple times, we would recommend around 6-8 times all in the same day to achieve the best results. So realistically you want to be free for an entire day to do this.