|Well-seasoned cast iron cookware is shiny and non-stick|
Heating the cast iron opens up the pores of the metal so the fat can flow in and fill the holes. The heat applied during cast iron seasoning also changes the chemical makeup of the oil to harden it.
A well-seasoned cast iron pan:
- performs better during cooking (since it is non-stick),
- is easier to clean up from (since it is non-stick), and
- can tolerate a bit more abuse than a new cast iron pan.
Cooking frequently with your cast iron and properly cleaning and drying your cast iron after use will go a long way toward developing a healthy seasoning. If your pan is rusted, see directions for rescuing abused cast iron cookware.
I use organic canola oil for my cast iron seasoning (also called rapeseed oil). Canola oil has a fairly high smoke point, and also a fairly high ability to polymerize, and is a drying oil.
NOTE: there's an interesting discussion about pre-seasoning, polymerization, iodine values, and more brainy stuff that you should read if you've got the time. If you are seasoning a naked bare cast iron skillet for the first time, you might consider using flaxseed oil as Sheryl suggests in the aforementioned article.
A well-used cast iron pan will actually acquire most of its beautiful coat of seasoning while you are using it to cook... as opposed to through repeated oven-seasoning sessions. But sometimes a good oven seasoning is in order.
Here's how you do it:
Oven Seasoning for Cast Iron
Start with clean and dry cast iron. Put a quarter-sized pour (1/2 teaspoon?) of canola oil in the center of the pan. Use a paper towel or clean cloth to liberally spread the oil all over (bottom too). Place the cast iron pan upside down in a 450 degree oven for 1 hour. Put a cookie sheet or aluminum foil underneath the pan to catch drips.
After an hour, the oil will likely appear somewhat mottled on the pan. Turn the oven off, and very lightly re-oil the pan (you can probably just use the same paper towel you used at first, with no additional oil). Stick your pan back in the oven to cool down very slowly. You may wish to re-oil it very lightly a few more times as it cools down to avoid mottling.
You can oven-season cast iron as many times as you like. But regular use is the best way to season your pan.
This process does generate a fair bit of smoke! It will probably stink up your house a bit. Consider oven-seasnoning your cast iron with your windows open and/or your stove hood fan on (assuming it actually vents to the outdoors). All the more reason to roast things (like chicken and vegetables) with your cast iron to develop seasoning.
Pre-Seasoned Cast Iron
Many cast iron skillets and dutch ovens come pre-seasoned these days. Lodge, in particular, has begun selling nearly all of their cast iron using their Pro-Logic seasoning method. While this pre-seasoning is helpful for getting a base coat of protection on the pan, true non-stick cast iron seasoning comes only from repeated use and proper care and maintenance.