AcrylPro Ceramic Tile Mastic, 1 qt. is a versatile, high-performance adhesive designed for installing ceramic tile, ceramic mosaic, and quarry tile. This multi-purpose white mastic is nonstaining and i for use over various surfaces including gypsum wallboard, exterior grade plywood, concrete, plaster, glass mesh mortar units, and even existing ceramic tile. It is for interior floors and walls, as well as interior surfaces that are exposed to prolonged water exposure, such as tub enclosures, showers, and countertops. Please note that it is not suitable for exterior surfaces. This mastic is nonflammable and coverage that varies based on the substrate, tile type, and size of the notched trowel used, with an average of one gallon covering approximately 21 square feet. The product comes in a quart-sized pail with an 18-month shelf life. Model Number: ARL4000QT