Larsen Plaster Weld/Bonding Agent. Quart. Bonds new plaster to any clean, structurally sound, interior surface. 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. Prepares the surface, can be used over paints having oil, rubber or vinyl bases, etc., pink and non-bleeding and concrete, brick, glass, metals and more are suitable sound surfaces, structurally.