PRIME 1 Acrylic is an interior and exterior water-based acrylic primer sealer with superior stain and Knot blocking properties. Product uses: Priming: PRIME 1 ACRYLIC can be used as a primer on a variety of surfaces: interior and exterior, hard and softwoods including mahogany, teak, cedar, pine and knotty wood, concrete, plaster, walls, ceilings, doors, trim; hardboard and MDF, PVC, including window and door frames, fascia and soffits. It can be used under and over most paints, including oil, enamel, and vinyl, and is perfect with Colourtrend paints. Stain Stop: PRIME1 ACRYLIC is an excellent stain blocker having been designed to prevent the bleed of household stains such as water stains, smoke damage, coffee, lipstick, tobacco, and nicotine. PRIME1 ACRYLIC has outstanding knot blocking properties and prevents the bleed of tannins on all hardwoods from showing through the finish topcoat.