AcrylPro Ceramic Tile Mastic, 3.5 gal. is a versatile, high-performance white mastic designed for installing ceramic tile, ceramic mosaic, and quarry tile. This multi-purpose adhesive works effectively over various surfaces including gypsum wallboard, exterior grade plywood, concrete, plaster, glass mesh mortar units, and existing ceramic tile. It is i for use on interior floors and walls, especially in areas exposed to prolonged water exposure such as tub enclosures, showers, and countertops. Please note that it is not suitable for exterior surfaces. This nonflammable mastic reliable coverage, with approximately 1 gallon covering 21 square feet, although coverage may vary depending on the substrate, tile type, and notched trowel size. The product comes in a 3.5-gallon pail and has a shelf life of 18 months. Model Number: ARL40003