A test program was undertaken by the U. S. Mine Safety and Health Administration to evaluate various materials for protecting aluminum overkast constructions against fire. Selected coatings and one covering were tested under large-scale, simulated mine fire conditions to determine their effectiveness as a fire barrier for protection of aluminum. Coating consisting of expanded vermiculite, limestone, and portland cement; mineral wool fibers in hydraulic setting, inorganic binders; cellulose mixed with liquid sodium silicate; and a fiberglass-reinforced surfacebonding mortar were particularly effective in protecting the aluminum structures against the heat of the simulated mine fire. Three inches of a ceramic-fiber blanket and a four-inch coating of phenolic spray foam also proved to be relatively effective barriers for fire protection under the conditions of the test.