Thompson's Stain Block Damp Seal is a high-performance interior coating that permanently covers damp, water, and other common household stains. It can be applied directly to damp walls and ceilings, which can then be decorated without risk of damp showing through. It is specially formulated to allow trapped moisture to evaporate over time to prevent paint flaking or wallpaper peeling off. Overpaintable in 4 hours. Seals and covers stains. Use on all interior walls and ceilings.