Foster® Weatherite™ Mastic 36-10

• WEATHERITE MASTIC has excellent brush, trowel, and spray properties, is non-flammable when wet and has a mild odor during application.
• WEATHERITE MASTIC forms a tough, fire-resistive dry film that is extremely flexible and provides a smooth, attractive finish being suitable for both indoor and outdoor applications.
• It has excellent adhesion to most foil facings. It can be used on residential low velocity air ducts as a closure joint sealant.
• WEATHERITE MASTIC complies with current requirements regarding use in meat and poultry processing areas under federal inspection.
•  WEATHERITE MASTIC meets requirements for LEED IEQ 4.2 Low-Emitting Materials, Paints and Coatings.
• WEATHERITE MASTIC contains no asbestos, lead, mercury, or mercury compounds.

Material Preparation

• Do not thin.
• WEATHERITE Mastic will appear to be thick, but this is a “false” consistency which breaks down readily on application.
• Stirring is not necessary.
• Apply only to clean, dry, oil-free surfaces.
• Keep container closed when not in use.

Application - Heavy Duty, hot and dual temperature surfaces

• Follow flashing recommendations when installed outdoors.
• MAST-A-FAB® Reinforcement : Apply a tack coat of Foster WEATHERITE Mastic at a thickness of 1/32 inch (0.8 mm). This is equivalent to 2 gallons per 100 square feet (0.8 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 (51 mm). Apply a finish coat of WEATHERITE Mastic at a minimum thickness of 1/16 inch (1.6 mm). This is equivalent to 4 gallons per 100 square feet (1.6 l/m2). This finish coat shall be applied no later than 1/2 hour after the tack coat and shall completely cover the membrane. This application shall provide a minimum dry film thickness of 54 mils (1.4 mm).
• Heavy Duty Applications - Up to 50% Greater Tensile Strength : Apply as above, substituting Chil-Glass #5 as the reinforcing membrane. Note that the membrane weave pattern will show through dried mastic. For best results, prime hygroscopic alkaline cements with Foster 32-22 Protektor® Sealant. Both the cement and the primer must be completely dry before the WEATHERITE Mastic is applied.
• Trowel Use clean steel trowel. Apply each coat in full thickness before initial set. Avoid excessive troweling.
• Clean-Up Use fresh water to clean brushes and equipment before product dries. Dry product may be removed with hot soapy water or strong solvents such as chlorinated solvent (non-flammable) or xylol (flammable).

• Store and apply between 40°F (4°C) and 100°F (38°C), protect from freezing until dry.
• To resist rain washoff, allow at least 12-15 hours drying time above 40°F (4°C), with a relative humidity of 50%.
• Higher humidity or lower temperatures may retard drying. 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.
• Always select WEATHERITE Mastic in the white color for use over Polystyrene on outdoor installations.