A furnace brick, or refractories brick, is a large block of solid refractory material utilized in lining most furnaces, kiln chambers, and fireboxes. A refractories brick has a lower thermal conductivity than other materials used for furnace lining due to its unique thermal properties. These properties enable the furnace brick to be an excellent insulator for the furnace, which provides a tremendous amount of energy savings over traditional materials such as graphite and metal. A refractorial brick may be formed out of either solid wood or glass, although wood provides more insulation, especially on cold winter nights. Glass offers more insulation than metal or wood and is more durable than both, though metal is less dense than glass. Both types of furnace lining are relatively inexpensive compared to materials that are used to manufacture other furnace lining products, though the refractories brick may be more valuable to a business because it is more cost-effective and able to perform better at lower temperatures.
Furnace bricks come in several different sizes and strengths, with the largest of these being up to eight inches in length. A smaller one foot size furnace brick may only provide up to one percent of the energy savings over using other materials, so businesses should ensure that they purchase the appropriate size. The thicker the furnace bricks used for furnaces and kilns are, the more expensive the unit will be to operate. Smaller refractorial bricks can be used for furnaces and kilns where there is little to no heating needed, such as the floor of a furnace room or a fireplace. Larger units, with up to six feet in length, are typically used for larger furnaces or kilns, where more heating is required. If an employer decides to use a larger furnace brick than required for a particular type of furnaces or kiln, then he or she can cut the unit in half by purchasing a half-size piece and combining it with the larger one.