how to season a cast iron skillet

Season a cast iron skillet by applying a very thin layer of high-smoke-point oil and baking it in an oven to create a hard, polymerized, nonstick surface.

Choose the right oil. Use a neutral oil with a high smoke point, such as canola, vegetable, or grapeseed oil. Avoid oils like olive or butter, which can burn and leave a sticky residue.
Apply a very thin layer. The most critical step is applying an extremely thin layer of oil. After coating the pan, buff it with a clean towel until it appears dry; any excess oil will result in a sticky, gummy, or uneven finish.
Bake at high heat. Place the pan upside down on the middle rack of an oven preheated to 425°F–500°F. Use a tray or foil on the rack below to catch any potential drips. Bake for 30 to 60 minutes.
Maintain through regular use. Once the initial seasoning is established, the best way to maintain and improve the pan's nonstick surface is to use it frequently for cooking fatty foods. Routine maintenance involves drying the pan thoroughly after washing and applying a light trace of oil.