Here's how you properly seal your cast iron cookware.
1. Using Crisco Vegetable Shortening coat cast iron generously but evenly on the cook surface bottom and sides.
2. Turn UPSIDE DOWN on cookie sheet and put in 500° oven.
3. After about 2 hours turn off oven and let cast iron cool along with oven.
4. Once cooled (usually another hour or so) wipe excess oil off cast iron and store as usual.