The best oil for seasoning cast iron is flaxseed oil, it’s a drying oil, it contains a high amount of polyunsaturated and unsaturated fats, 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.
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.
Keep reading to find out more about the different cooking oils for seasoning, otherwise read the seasoning guide to get started.
Cold pressed vs unrefined vs refined: which is better?
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: which is better?
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: which is better?
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?
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.
What’s the smoking point of an oil mean?
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.
The different cooking oils and their seasoning effectiveness
Because everyone doesn’t own flaxseed oil, or their shops might not supply it, I’ve taken the time to discuss the other cooking oils, so you know the best one in your house to use for seasoning.
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.
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 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.
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 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.
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 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 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 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 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 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.
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.
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 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.