When mixed with water, A.W. Perkins Castable Fire Brick sets to a light brown color, hard as brick. Use it for replacing worn-out firebrick in the bottom of woodstoves, cast it into irregular shapes, or use it as a solid stone bed. This product has unbelievable strength. It can withstand temperatures up to 2200 degrees F. Sold in cases of two, each one gallon container (12.5 lbs.) covers one square foot at 1 1/2" depth when mixed with one quart of water. Easy directions are on the container.