Lucas #8500 Silicone Mastic is a high solids non-shrinking moisture cure silicone mastic intended for flashing, sealing and repairing roofs, walls, masonry and metal roof seams & fasteners. It features minimal odor, contains no solvents, and less than 10 grams per liter VOC—yes, you can seal confidently without turning your space into a chemistry lab.

Key Features & Design

• High solids non-shrinking moisture cure silicone mastic for flashing, sealing and repairing roofs, walls, masonry and metal roof seams & fasteners.
• Minimal odor, contains no solvents and less than 10 grams per liter VOC.
• Excellent adhesion to concrete, masonry, vinyl, fiber cement, polyurethane foam, EPDM, aged acrylic coatings, granular cap sheet, wood, metals, Kynar® and most other common building materials.
• May be applied to wet and underwater surfaces.
• Lucas #8500 is a non-reactive oxime, neutral cure silicone and will bond extremely well to a wide variety of surfaces. It does not emit acidic byproducts during cure like acetoxy silicone sealants.
• Lucas #8015 TPO Primer is required for application TPO roofs.
• Application: Surface to be sealed must be clean but may be slightly damp. Apply with a trowel or 4 inch chip brush at a minimum of ¼ inch thick and taper the edges of the application.
• Immediate weather resistant.
• Application below 32ºF (0º C) is possible however curing requires free moisture in the air and will not begin until the temperature is above freezing.
• Use to seal penetrations and terminations prior to application of Lucas #8000 100% Silicone Roof Coating.