#950 Primer / Sealer – Stain Blocker-950

Water Based – Clear Acrylic Primer – Blocks Asphalt Oils From Staining

Western Colloid’s #950 Primer/Sealer – Stain Blocker is a water-based, clear, acrylic primer/coating. It is formulated with premium acrylic resins that are designed to stop asphalt residues and oils from staining the acrylic coating system. #950 Primer/Sealer also aids in the adhesion of the acrylic coating to the substrate. #950 Primer/Sealer should be used as a primer coat over existing granulated asphalt roofing, mastics and coatings where staining of the acrylic coating system is a concern. Use over existing solvent based asphalt mastics and coatings on Western Colloid metal sealing systems. Not for use over smooth asphalt emulsion or other smooth asphalt or modified bitumen surfaces. For increased adhesion to smooth asphalt surfaces or ponding conditions use #970 A2A Bonding Primer


  • Specially formulated to block asphalt oils from staining.
  • Aids in adhesion under acrylic coatings.
  • Excellent primer over solvent based mastics.