No, you should never use PVA to prime a surface before tiling. PVA (Polyvinyl Acetate) is often used to seal things, or used as a glue in crafts and woodworking but should not be used as a sealer before tiling. This is because when PVA comes in contact with cement, used in lots of tile adhesives, it produces ‘Acetic Acid’. This acetic acid stops the cement based adhesive from curing properly and will eventually weaken the bond of the adhesive. You should always use the correct sealer, such as Larsen Acrylic Sealer for Porous Substrates , as this will contain no PVA.