I do not recommend cleaning cast iron cookware by placing it in a fire. People have reported the cookware may crack or warp.
Sand- or other media-blasting will also make the piece worthless to collectors.
I have a lot of cast iron cookware, and used to scrape it by have or a wire wheel on an electric drill.
I finally settled on the easiest way to clean cast iron, and it is the method recommended by The Pan Man.
http://panman.com/
Oven cleaner.
It has to be the heavy-duty oven cleaner which is lye. Regular oven cleaners (i.e., glycol ethers) will work, too, but it takes much longer. A lot longer.
Get a shallow cardboard box and line it with a plastic garbage bag. Spray the piece with oven cleaner in the bag, and close the bag over the piece.
Forget about the piece for a while. Then rinse it, and repeat the process until it is stripped.
Very, very easy. The easiest method I've found so far.
I recently cleaned nine pieces that were very heavily covered in carbon. Couldn't even tell that one piece was a very old hand-hammered piece, and another poiece is an old Vollrath.
I need to contact someone I know at the Griswold and Wagner Society, to see if she can help me date the hand-hammered piece.
Here are pictures:
http://www.thesmokering.com/forum/viewtopic.php?t=45511
Great prices on all nine pieces off craigslist.
