Valspar interior/exterior stain block/bonding primer is a high-quality latex primer designed for the professional painter. This low VOC primer is superior adhesion over glossy surfaces, drywall, cured plaster, masonry, wood, galvanized metal, and aluminum. In addition, Valspar stain blocking/bonding primer blocks stains from tannin bleed, knots water damage, crayons, and grease. Valspar stain blocking/bonding primer is also sandable making it a great enamel undercoater. Covers approximately 250 to 300 sq. ft. per gallon depending on surface.