I don't have much experience at this, but I was told by an older blacksmith, that I needed to protect the cast iron pan from getting to hot and cracking. I mixed - 1 part portland cement with 3 part sand, added a little water to make it into a paste. I place a 6" stove pipe over the tue to protect the teu from the mixture and then I coated the bottom of the pan with about 1 to 1.5 inches of the mix. The mix may be a little bit thick, so next time I need to line the pan, i'll use less mixture in the pan. I have a little Champion Farm forge that I lined this way and it turned out real nice.