Up date I can (for now) only find pearlite, sand (backyard),silica sand (kitty litter),red clay(brick, clay pipe), ash, silica furnace cement, cement(Hydrophilic and portlend). Thats all I can find or make. I made a patch for my old way to small forge with 2 parts clay 1 part silica sand 1 part ash 12 part Hydrophilic cement. Wateing for it to cure hope its more durable then just the silica cement that I burnt thrue.