Scrub off loose rust with steel wool or a stiff brush
Wash the pan with warm water and mild dish soap
For heavy rust, soak in a 1:1 vinegar and water solution for 30 minutes to 1 hour
Check frequently during soaking to avoid damaging the iron
Scrub again after soaking to remove loosened rust
Rinse thoroughly with warm water
Dry completely with a towel
Heat the cast iron on the stove or in the oven to remove all moisture
Rub a thin layer of cooking oil over the entire surface
Bake upside down in the oven at 450 to 500 F for 1 hour
Let it cool in the oven
Repeat seasoning if needed
Store in a dry place to prevent future rust