High-strength thin set mortar for interior or exterior use. For exterior applications or extra high-strength use acrylic mortar admix in place of water. Use to bond ceramic, mosaic, and quarry tiles, cement tile, precast terrazzo, natural stone, marble, and minibrick to concrete substrates; masonry, gypsum wallboard, cement backer board, and plywood. Not recommended for use over wood or vinyl flooring or their adhesive residue, metal, fiberglass, particle board, masonite, Luan plywood, or lightweight concrete. Approximately 90 to 100 sq. ft. per 50 lb. applied with 1/4" x 1/4" notched trowel.Pot life: 2 hours. Allow to cure 24 to 72 hours before grouting. Clean up immediately with water. NOTE: Do not use grayon marble.\