Caring for cast iron
Seasoning is oil heated until it turns into a hard, slick, plastic-like layer bonded to the iron. Every time you cook with fat in a hot pan, you add a little more. Bare gray patches mean the layer is thin there.
Dry the pan and oil it lightly
Iron rusts when it stays wet, so towel the pan dry after washing, then warm it on a burner for a minute. Rub in a few drops of oil and wipe off the rest until the pan looks nearly dry. A thick coat turns sticky.
Test yourself
Questions from the interactive lesson, with the answer and the why.
What exactly is the black coating on a well-used cast iron pan?
Oil heated until it hardened onto the iron. Oil heated past its smoke point links into a hard polymer film.
True or false: Soap will ruin a seasoned cast iron pan, so you should never use any.
False. Mild dish soap is safe because seasoning is baked hard, but skip long soaks and dry the pan right away.
What went wrong? You leave a cast iron pan in the rack to air-dry overnight. In the morning it has orange spots.
It air-dried wet, so it should have been dried and oiled. A quick wipe and a thin coat of oil prevent rust.
Fill the blank: A thick coat of oil baked on a pan at 230°C (450°F) comes out ___ instead of hard.
A thick coat of oil baked on a pan at 230°C (450°F) comes out sticky instead of hard. Thick oil can't harden all the way through, so it stays gummy.
Your pan is newly seasoned, with only a thin layer. Which dinner is hardest on the new seasoning?
Tomato sauce simmered for an hour. A long acidic simmer can strip a thin seasoning and add a metallic taste.