Henry 314 Readyset premixed mastic adhesive for ceramic, porcelain, and quarry tile. Do not use for lug back ceramic tile or pre grouted wall tile sheets. Bonds to concrete, concrete block, cement backer board, gypsum drywall, plaster, underlayments, wood substrates, brick, and existing ceramic tile. Glossy painted surfaces and glazed ceramic tile must be abraded. Do not use over mortar beds, gang showers, or walls made of plywood or particleboard.