Wash the skillet with hot water and a small amount of mild soap if needed
Scrub off rust, old residue, or flaky seasoning with steel wool or a stiff brush
Rinse and dry completely
Place the skillet on the stove over low heat to remove all moisture
Apply a very thin layer of cooking oil to the entire skillet, inside and out
Wipe off all excess oil until the surface looks almost dry
Preheat the oven to 450°F to 500°F
Place the skillet upside down on the middle oven rack
Put foil or a baking sheet on the lower rack to catch drips
Bake for 1 hour
Turn off the oven and let the skillet cool inside
Repeat the oiling and baking process 2 to 4 times for a stronger seasoning
Use the skillet regularly and avoid soaking it in water