Foster® Monolar® Mastic 60-90

• Foster® Monolar® Mastic is a tough, flexible, fire- resistive, elastomeric finish for protection of outdoor thermal insulation.
• It contains chlorosulfonated polyethylene rubber (formerly known as Hypalon®*).
• It is an excellent vapor retarder for low temperature insulation on tanks, pipework, ductwork, vessels and fittings.
• Monolar® Mastic provides outstanding weather barrier protection, showing good color retention, excellent chemical resistance and durability.
• Monolar® Mastic trowels easily and smoothly without drag or excessive stringing.
• It features higher volume solids than some other vapor retarder mastics, reducing the number of gallons that need to be applied.

• Apply between 40°F and 100°F.
• For best results, select Elastolar® 95-44 for insulation joint sealing under Monolar® Mastic.
• Always test plastic materials for compatibility when using a solvent-based product.
• Outdoor horizontal surfaces must always drain completely.
• A pitch of at least 1/2” per foot (4 cm/m) is recommended.
• Make certain this product is completely dry and the area free from solvent odor if food is involved.
• Select Monolar® Coating 60-95 (white) or 60-96 (gray) for airless spray or brush application.31

Material Preparation

• Stir Well.
• Do Not Thin.
• Apply only to clean, dry surfaces.
• Keep container closed when not in use to prevent solvent evaporation.

Application

• To prevent water vapor and moisture infiltration, proper and complete flashing is required.
• Follow flashing specifications.
• Normal Service: Apply a tack coat of MONOLAR® Mastic at a thickness of 1/32 inch. This is equivalent to 2 gal./100 sq. ft. 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 MONOLAR® Mastic at a minimum thickness of 3/64 inch. This is equivalent to 3 gal./100 sq. ft. This finish coat shall be applied no later than 2 hours after the tack coat and shall completely cover the membrane. This application shall provide a minimum dry film thickness of 33 mils (0.8 mm).
• Severe and Cryogenic Service: Increase the tack coat coverage to 3 gal./100 sq. ft. and the finish coat to 4 gal./100 sq. ft. Allow the tack coat to set up before applying the finish coat on vertical surfaces. This application shall provide a minimum dry film thickness of 46 mils (1.2 mm). On rough or porous insulation surfaces additional product will be required to achieve the full surface dry film thickness. The application rate may need to be increased by up to 20% or more to achieve minimum film thicknesses. User shall determine required material based on specific substrates and application methods.
• Trowel: Use clean tools. Work in long, even strokes to ensure uniform thickness. Wet tool with detergent foam (not soap) occasionally to prevent a buildup of dried mastic. RUBBER GLOVE: Best appearance may be achieved by smoothing wet MONOLAR® Mastic with detergent foam (not soap) on a clean glove or brush, being careful not to pick up any MONOLAR® Mastic onto the glove or brush.

Clean Up 

• Use xylol (flammable) or chlorinated solvent (non-flammable) for cleaning equipment. Dried MONOLAR® Mastic is extremely difficult to remove.

¹ - Subject to the nature of material being coated. Wet coverages shown below are for smooth, non-porous surfaces. Porous or rough surfaces will require higher gallonage to attain required dry thickness.

² - Monolar® Mastic meets the permeance requirements of ASTM C755-19 for below ambient vapor retarder coatings.

³ - Tested at coverage rate of 25 sq. ft./gal. Applied to 1/4 inch (6.4 mm) inorganic reinforced cement board. The flame spread may vary at different product thicknesses and/or when applied over other surfaces.

Store between 40°F and 100°F.