Eliminates the Use of Frame work for Mirror Fixing Weather Seal Silicone Sealant is an one part neutral cure, medium modulus, lowodor, construction grade sealant that offers excellent adhesion, weather ability and compatibility with wide variety of materials. BOSS 389 is ideally suited for weather proofing, waterproofing, sealing, expansion and control joints and general purpose glazing. It has excellent adhesion to glass, glazed surfaces, galvanized steel, anodized aluminum, concrete, cement, wood, ceramics, painted surface and many plastics.