Fireproofing is the popular name for the coatings and methods used to protect paper, plastic, textiles, wood, and other materials against fire. Fire prevention experts, however, consider the term fireproofing misleading because even such noncombustible materials as steel and concrete are affected to some degree by intense fire. Steel can weaken or melt and concrete can crack. Experts instead refer to materials that have been protected against fire as fire resistant or fire retarded. They call the substances that are used to protect such materials fire retardants.
Fire retardants help prevent materials from burning or being severely damaged when exposed to fire. Some increase the time it takes for treated articles to ignite. Others cause a material to extinguish itself if it is ignited by a brief fire, thereby preventing the fire from spreading to surrounding objects.
Fire results from the combination of fuel, heat, and oxygen. When solid materials are heated to a high enough temperature, their molecules break down to produce flammable vapors that can chemically react with the oxygen in air. Fire retardants help materials resist fire by interfering with these reactions. For example, a combustible surface may be protected against fire by being covered with a special fire-retardant intumescent coating. Upon exposure to fire, an intumescent coating swells up to form a thick layer of insulating foam between the surface (the fuel) and the fire (the heat).
Many fire retardants produce physical or chemical changes in a material to make it less flammable. Some, for example, cause a material, when exposed to fire, to become coated with a fire-resistant layer of charred carbon. Retardants that alter the flammability of materials are applied in a number of ways. For example, textile manufacturers obtain nearly permanent fire resistance in natural and synthetic fabrics used in making carpets, clothing, draperies, and upholstery through processes that molecularly bond retardant compounds to the fabric. Temporary fire retardation can be obtained by soaking fabrics in solutions of such chemicals as borax, boric acid, diammonium phosphate, and ammonium sulfate. Paper manufacturers often add similar chemicals to paper and cardboard.
In many countries, materials used to build houses, schools, and other buildings must meet fire-resistance standards. These standards are typically set by local governments. Other regulations require that certain types of clothing, such as children’s sleepwear, be treated with fire retardants.
