Berger Premium Acrylic Sealer Undercoat seals and undercoats interior surfaces and is easy to sand for a smooth finish. Berger Acrylic Sealer Undercoat has excellent hiding power to prepare the surface for painting with oil or water based top coats and is suitable for use over surfaces where a oil or water based paint has been previously used, following preparation instructions on pack. It’s a water based acrylic paint so it’s easy to clean up afterwards.