Dulux Trade Stain Block Primer is a water-based primer suitable for use on interior walls and ceilings. It is formulated to prevent the migration of stains through the finished paint film and also to seal and bind dry, friable and powdery interior surfaces such as plaster, brick and distemper. It is the effective treatment for stains caused by: water-based and solvent-based inks, crayon, biro, coffee, grease, scuff marks, water and nicotine.