Rust
The Cause
Cast iron cookware can develop rust when exposed to moisture for extended periods of time. However, rusting does not make it harmful in any way. If you leave your cast iron cookware in the sink to soak, put it in the dishwasher or let it air dry, it will rust. Moisture-prone environments such as a cabinet near a dishwasher, an open cabinet in a humid location, or outdoor storage can also cause rusting.
The Fix
Follow these steps to restore your cast iron skillet.
Step 1. Scour
To prepare your cast iron cookware for re-seasoning, start by scouring its surface with warm, soapy water and a metal scouring pad. This is perfectly safe since you will be re-seasoning the cookware anyway. Once you are done, rinse it thoroughly and dry it by hand.
Step 2. Oil
Apply a thin layer of oil inside and outside the cookware. Using too much can cause stickiness.
Step 3. Bake
To achieve the classic black patina on your cookware, place it upside down on the top rack of your oven. Cover the bottom rack with aluminum foil to catch any excess oil that may drip off the cookware. Bake at 450-500 degrees Fahrenheit for one hour. After baking, allow it to cool before repeating the process as necessary.