5921 Paintable Undercoat and Sound Eliminator Black Aerosol is a flexible, paintable, black undercoat. It combines the flexible sealing properties of rubber, with superior coating capabilities. An effective textured coating that dries fast without thick peaks and thin pockets which tend to weaken the film and trap moisture. A durable protective coating that helps retard the effects of rust corrosion, moisture, fumes, dust, heat and cold. An excellent rust protective coating for autobody repair. Creates an effective sound barrier that reduces vibration and deadens sound in wheel wells, quarter panels, fenders, frames, under carriages, spot repairs and welded joints. When top-coating 5921 Paintable Undercoat and Sound Eliminator, it is best to use a primer first and then paint.