To season cast iron, you can use all cooking oils and fats, but certain types are highly recommended due to their effectiveness, availability, affordability, and high smoke point.
Recommended Oils for Cast Iron Seasoning
While nearly any cooking oil or fat can be used to season cast iron, some oils are consistently preferred for their ability to create a durable, non-stick surface. These oils excel because they can reach their smoke point without burning, allowing them to polymerize effectively and bond to the iron.
Here are the top recommendations:
| Oil Type | Key Benefits |
|---|---|
| Vegetable Oil | Widely available, very affordable, and an effective all-around choice. |
| Melted Shortening | Forms a very durable, protective seasoning layer that holds up well over time. |
| Canola Oil | Possesses a high smoke point, making it excellent for the polymerization process. |
Many specialized cast iron seasoning sprays also utilize these types of oils, indicating their suitability for creating a robust and long-lasting seasoning layer.
Why These Oils Are Preferred
The choice of oil for seasoning isn't arbitrary; it's based on specific characteristics that lead to the best results:
High Smoke Point
Oils with a high smoke point are crucial because seasoning involves heating the oil past its smoke point, allowing it to polymerize. This process transforms the oil into a hard, non-stick, and protective layer bonded to the cast iron. Oils that smoke at lower temperatures can break down too quickly, leading to a sticky or gummy residue instead of a proper seasoning.
Affordability & Availability
The most recommended oils are typically inexpensive and readily available in most kitchens or grocery stores. This makes the seasoning and re-seasoning process accessible and convenient for regular maintenance.
Effectiveness in Polymerization
The chemical structure of these oils allows them to effectively polymerize when heated. Polymerization is the process where oil molecules break down and then rearrange to form a plastic-like coating that fills the microscopic pores in the cast iron, creating a smooth, non-stick surface.
Best Practices for Seasoning
No matter which oil you choose, the application technique is key to successful seasoning:
- Apply Thin Coats: The most common mistake is using too much oil. A very thin, almost invisible layer is ideal. Excess oil will lead to a sticky, gummy finish.
- Wipe Off Excess: After applying oil, use a clean cloth or paper towel to wipe off as much as you can, as if you're trying to remove it all. A microscopic layer will remain.
- Heat Properly: Place the oiled cast iron upside down in an oven preheated to above the oil's smoke point (e.g., 450-500°F or 232-260°C).
- Bake Long Enough: Bake for at least one hour at the high temperature, then turn off the oven and let the cast iron cool completely inside.
- Repeat Layers: For the best and most durable seasoning, repeat the oiling and baking process several times. Each layer adds to the strength and non-stick properties of your cast iron.
Oils to Use with Caution or Avoid for Seasoning
While theoretically any fat can work, some oils are less ideal for initial seasoning due to their properties:
- Olive Oil: Generally has a lower smoke point compared to vegetable or canola oil. While fine for cooking, it can result in a stickier seasoning if not handled carefully, or may break down too quickly during the seasoning process.
- Flaxseed Oil: Some cast iron enthusiasts swear by flaxseed oil for its ability to create a very hard seasoning layer. However, it's significantly more expensive and some users report that its seasoning can be brittle and prone to flaking over time.
- Butter: Has a very low smoke point and contains milk solids that will burn, making it unsuitable for seasoning. It's excellent for cooking, but not for creating a polymerized layer.
