A topic near and dear to my heart! I am addicted to cast iron! I buy at flea markets, yard sales, and auctions; mostly because I enjoy refurbishing it. I use the fire and brush method. I keep a big pile of old white oak barn lumber that has been dry for 50 years. I just build a good oak fire in an open pit and wait for it to reach a nice red glow.(low flame, with little smoke) Then, I add iron. If it has a heavy build-up, you can literally see it turn gray/white and begin flaking off. At night, you can see the iron itself reach a red glow. After I remove it from the fire, I let it sit until it is cool to the touch, and then attack it with a series of wire brushes on a power drill. This will remove the build-up flakes and rust. Once it is clean, I re-coat with olive oil, or vegetable oil, and place in the oven for about an hour at 350 degrees. (do this while your wife it away, it does tend to smell up the house) When it comes out, it will look like new "Lodge" ware, and water will bead off it like a freshly polished car. I agree with other posts that the build up is what really makes cast iron cook well, but I prefer to be the one who adds the gunk to my iron. I do avoid small pots, as they have the greatest chance of having been used to melt lead. Sure, there is no way to know what purpose iron served in its' past life, but most well-used skillets and pots got their build-up the honest way...they earned it.
