ZINSSER B-I-N® Shellac-based primer is a primer-sealer, stain blocker recommended for almost all surfaces. It blocks grease spots, fire, smoke, water stains, ink, crayon, knots and sap streak stains and seals odors resulting from water and fire damage. It seals knots, porous wood and spackled areas. It sticks to ceramic tile, glass, metal, plastic and hardboard.