Acid-resistant brick can protect concrete floors from industrial chemicals. Brinks, a Louisiana refractory contractor, has been installing acid-resistant bricks in chemical plants for 20 years. This article describes how Brinks, in 1994, installed a red-shale acid-brick floor over an asphaltic membrane applied to the concrete substrate. The hot-applied asphaltic membrane was reinforced with an asphalt-impregnated glass-fiber mat. The acid brick stops most chemicals and protects the asphaltic membrane from physical damage, abrasion, and extreme temperature. But if chemicals do penetrate the brick flooring, the asphaltic membrane keeps them from reaching the concrete substrate. The type of acid brick and chemical-resistant mortar that's needed depends on the chemicals and temperatures to which the floor will be exposed. Polyester mortars, for example, resist bleaches, hydrogen peroxide, dilute sodium hypochlorite, oxidizing and nonoxidizing acids, weak alkalies, salts, and chlorine gas at temperatures up to 225 degrees F. Phenolics, on the other hand, resist solvents, oils, greases, high concentrations of nonoxidizing acids, and mild alkaline solutions but not strong alkalies. The article contains a sidebar that describes chemical-resistant mortars in detail. The article also describes how to attain good workmanship when laying acid brick: Butter the bottom of the brick or butter the floor first with a 1/8-inch bed of mud. The bed joint is important in creating a level base for the brick. Neither the subfloor nor the brick are ever perfectly level. Without the bed joint, the brick can move or wobble, maybe even crack. Excess mortar that oozes from the joints should be removed immediately with a trowel (or later with a chisel or paint scraper). Brinks typically buys brick with a waxed top surface that helps keep the brick from getting stained. After the job is done and the mortar has cured (for 3 to 7 days at 70 degrees F), a 60-psi wet steam hose is used to melt away the wax. Waxing adds 4 cents to 5 cents to the cost of each brick.