Foster® Fire Resistive C.I. Mastic™ 65-05

• FOSTER® FIRE RESISTIVE C.I. MASTIC™ is a tough, durable, high solids, vapor retarder and weather barrier mastic for the protection of thermal insulation in outdoor service.
• Its excellent weather and fire resistance makes it suitable for use in place of conventional asphalt cutback mastic.
• It is an ideal surface coating for low temperature insulating applications where the insulation used is not affected by mild solvents.
• FIRE RESISTIVE C.I. MASTIC™ may also be used on heated lines, vessels and equipment in intermittent or dual temperature service to prevent the entrance of water vapor into the insulation during off periods or on cold cycles.
• It is outdoor rated and UV resistant.

Material Preparation

• Do Not Thin.
• Stir well, but do not use sticks or boards, which would splinter or otherwise contaminate the product.
• Apply only to clean, dry, oil-free surfaces.
• Keep container closed when not in use.
• Foster® 65-05 cannot be successfully applied by brush or spray.

Application 

• Proper and complete flashing is required.
• Follow flashing specifications.
• If a decorative coating is to be used over the FIRE RESISTIVE C.I. MasticTM, allow a minimum of 30 days drying time before application.
• Outdoor and Heavy Duty Service: Prime dusty insulation or porous cements with 65-05 cut 50/50 with mineral spirits. Apply a tack coat of Foster® FIRE RESISTIVE C.I. MasticTM at a thickness of 1/16 inch (1.6 mm). This is equivalent to 4 gallons per 100 square feet (1.6 l/m2). Embed Foster® MAST-A- FAB® White Membrane into wet tack coat. Smooth membrane to avoid wrinkles and overlap all seams at least 2 inches (5 cm). Apply a finish coat of FIRE RESISTIVE C.I. MasticTM at a minimum thickness of 1/8 inch (3.2 mm). This is equivalent to 8 gallons per 100 square feet (3.3 l/m2). This finish coat shall be applied no later than 1 hour after the tack coat and shall completely cover membrane. This application shall provide a minimum dry film thickness of 125 mils (3.2 mm).
• Heavy Duty Applications – Up to 50% Greater Tensile Strength: Apply as above, substituting CHIL-GLAS® #5 as the reinforcing membrane. Note that the membrane weave pattern will show through the dried mastic.
• Trowel: Use clean tools and equipment. Work in long, even strokes to ensure uniform thickness. Wet tools in mineral spirits (flammable) occasionally to prevent build-up of dried mastic.

Clean Up 

• Clean tools and equipment with mineral spirits (flammable) or chlorinated solvent (non-flammable).

• Always test foil and paper facings for acceptable adhesion before using.
• Outdoor horizontal surfaces must always drain completely.
• A pitch of at least 1/2" per foot (4 cm/m) is required.
• FIRE RESISTIVE C.I. MASTIC™ may weather to a dark gray color.
• Always test plastic materials for compatibility when using a solvent-based product.
• Do not use on polystyrene foam.