... to save energy. Usually dense firebricks are used in applications with extreme mechanical, chemical, or thermal stresses ... form, and insulate far better than dense bricks. In any case, firebricks should not spall under rapid ... temperature changes.To make firebrick, fireclay is baked in the kiln until it is partly vitrified, and ... of fire-brick is 9 x 4.5 x 3 in. (230 mm x 115 mm x 75 mm)The silica ...