I sell a bunch of cast iron skillets. They are one of the most useful antiques because they never go out of style and never wear out. Some antiques are damaged by use, but not cast iron. So if you cook in cast iron (new or old) you might find this information useful. But then, you probably know this already.

Instructions for Seasoning Cast Iron Cookware

Wash in warm sudsy water. If the pan is new, use a scouring pad to remove all
manufacturing residue. Rinse thoroughly and dry completely.

Coat inside and out with any vegetable oil and place in an oven at 300 degrees for about
an hour. Remove from oven and allow to cool in the open air. Use paper towels to
remove any excess oil. It should now be black and should stay black throughout it's
long, useful life.

Before each use, preheat for a minute or two. This will give you the natural non-stick
surface that makes cast iron so popular. It also allows food to cook evenly from the
beginning. Cast iron is an excellent conductor of heat.

To clean cast iron, wipe it out and rinse in very hot water. Don't put it in the dishwasher.
Avoid the use of detergents which will remove the seasoning. Always dry thoroughly
before putting away. It's a good idea to reseason cast iron cookware occasionally.

Cast iron works great in the oven or on top of the stove, but never put it into a
microwave oven.

(When you pass your cast iron on to the next generation, it is good to include a copy
of these instructions.)