Plaster-Weld® The original plaster bonding agent is a patented formulation incorporating polyvinyl acetate homopolymer. Designed for interior use only, Plaster-Weld® provides high performance bonding of one-coat finish plaster and/or two and three coat work to concrete ceilings, walls, columns, beams, and other structurally sound surfaces. Plaster-Weld® prepares the surface to allow you to plaster directly to concrete over electric radiant heat cable, and to bond cement mortar beds to smooth concrete for installation of rigid foam installation. Concrete, brick, block, glass, ceramic tile, wallboard, metals (e.g. sheet lead in x-ray rooms) and marble are suitable surfaces. Plaster-Weld® can be used over paints having oil, rubber, or vinyl bases, and over silicone-treated surfaces, as well as latex paints. Do not apply over water soluble paints, ie. casein or calcimine paints.