Cast iron seasoning is an important step in maintaining the durability and performance of cast iron cookware. However, many cast iron cooks debate which oils and fats are best to use in the seasoning process. Once you’ve chosen your preferred out, we recommend checking out our most popular article on seasoning cast iron.
Truth be told, there are many oils that work just fine but here we’ll break down key factors in choosing the right oil: Smoke Point, Flavor, Cost and Impact on Polymerization and give our recommendation for the best oil to use for seasoning cast iron down below!
A Brief Overview of Seasoning
Seasoning is the process of applying a thin layer of oil to the surface your cast iron and heating sufficiently to the point of polymerization in which the oil creates a hard, nonstick surface. This layer acts as a barrier between the metal and the food, preventing rust, reducing sticking, and making cleanup easier.
Choosing the right oil has a significant impact on not only creating a well seasoned cooking surface but may impact the durability of your seasoning as well as the taste of the foods you cook on that newly seasoned surface.
Here are the 3 main consideration you should take into account when picking the best oil for seasoning cast iron:
1. Smoke Point
The smoke point of an oil is the temperature at which it begins to degrade and emit smoke. This happens because heat causes the oil’s molecules to break down, form new compounds and release free radicals which often leads to smoke and fumes. It’s important to understand that an oil cannot polymerize fully until heated slightly past its smoke point. It is at just above the smoke point where the oil changes its molecular structure and forms the carbonized and hardened layer know as the “seasoning” that bonds to the cast iron.
It’s important to understand the difference between oil used for cooking versus oil used for seasoning. When cooking with oil that has been heated past its smoke point, this can impact the taste, smell, nutritional value as well as the foods safety. Overheating oil when cooking and the release of free radicals can be harmful when ingested and have been found to contribute to chronic health problems.
However, the breakdown and release of free radicals in oil during the seasoning process is a necessary step to initiate polymerization and create your cast irons non-stick surface. After your cast iron has been successfully seasoned, free radicals are no longer present.
In terms of choosing an oil based on smoke point alone, unrefined Flaxseed oil has the lowest smoke point at just 225°F and has become a popular choice for seasoning cast iron. However, this oil is not recommended for seasoning as it has a mild nutty flavor that could impart unwanted flavor when cooking. Similarly, the low smoke point makes unrefined Flaxseed oil a poor candidate for cooking which could leave you with a bottle of oil that’s not being used very often.
The oil used in the seasoning process can affect the flavor of the food being cooked in your cast iron. Oils are made up of natural compounds including fatty acids. These fatty acids are the building blocks of fat in our diet and are the chemical compounds that can heavily impact flavor in cooking. The combination and level of these fatty acids in cooking oil, especially when heated, has a great impact on the flavor of your food.
While your seasoning layer has undergone a series of chemical reactions to turn into a hard, non-stick surface, the seasoning is still just a hardened layer of oil. When you heat your pan to start cooking, the carbonized oil heats up and the fatty acids within release flavor compounds that can contribute flavor to the food that’s being cooked.
Finding a neutral oil for seasoning cast iron is essential so that you don’t introduce any unwanted flavors in the food being cooked. To illustrate, I’d offer up comparing sesame oil versus canola oil in seasoning cast iron. For many familiar with asian cooking, sesame oil is known for its distinct nutty flavor and rich aroma but when used in excess it can often overwhelm a dish or sauce. Canola oil, on the other hand, is known for its neutral flavor and aroma. Imagine having cast iron seasoned with sesame oil influencing the flavor of your blueberry pancakes!
In terms of choosing an oil based on flavor neutrality, we recommend using canola oil since it’s one of the most neutral flavored oils available and incredibly versatile, often being used for baking, frying and sautéing among other uses.
3. Price and Availability
Anyone who’s been to the grocery store lately knows that the price of cooking oils has climbed significantly, especially for organic and more premium oils such as Avocado Oil, Coconut Oil and Flaxseed oil. This can greatly influence what oil you should consider for seasoning cast iron.
Generally speaking, the most cost effective options that can be found at most grocery stores are vegetable, canola and corn oils which come in anywhere from $0.06-$0.10 per Fluid Ounce. These oils are often available in large bottles from 32 Ounces up to 1 Gallon in some large grocery stores.
For those cast iron cooks looking for flaxseed oil or avocado oil, you can expect to pay anywhere from $0.40-$1.00 per Fluid Ounce depending on where you live. It’s important to note that these oils are not commonly available at most grocery stores and, when available, aren’t often sold in large bottles.
In terms of choosing an oil based on cost alone, we recommend vegetable oil as it’s often the most affordable of all the available oils in the supermarket. However, vegetable oil is often considered one of the least healthy cooking oils because of its mix of unhealthy fatty acids.
The case against Lard and Bacon Grease
Most cast iron cooks have surely heard that Lard and other animal fats have traditionally been used to season cast iron. Lard is rendered animal fat (commonly from Pigs) that has a neutral taste. Bacon grease is similar to Lard but has a strong smokey and salty flavor.
Both can certainly be used for seasoning cast iron, however, it’s not recommended if you are not using your cast iron frequently. Animal fats contain significantly higher amounts of impurities and free fatty acids than vegetable-based oils. If stored for too long, these types of fats can go rancid and degrade the quality of your seasoning.
So what’s the BEST oil to use for Seasoning cast iron?
We recommend either Canola or Grapeseed Oil for seasoning cast iron.
Both Canola and Grapeseed oil have high smoke points, 425°F and 420°F respectively, meaning they can stand the exposure to high heat during the seasoning process. Additionally, because of their high smoke points, the oils are safe to use for high-heat cooking such as searing, sautéing and frying but also neutral enough to use in baking.
The only factor to consider between Canola and Grapeseed oil is your budget and grocery availability. Canola will likely be one of the most affordable and almost universally available oils while grapeseed oil could cost almost double the price per ounce and may not be available at your local grocery store.
Choosing the best oil for seasoning cast iron has been an often debated subject in the cast iron cooking community but truth be told, most oils and fats are perfectly capable of doing the job. The choice comes down to preference and key factors include smoke point, flavor and cost.
While cast iron cooks surely have their preferred oil (many sticking to lard or bacon grease), we recommend either canola or grapeseed oil. They’re both neutral oils, lower on the price spectrum and can be used for cooking in addition to seasoning. However, the key difference in the two would be price and availability.
Let us know how your seasoning is going and tell us which oil you prefer!