Foster® H.I. Mastic® 90-07

• Store and apply between 40°F and 100°F.
• Protect from freezing until dry.
• As with all asphalt emulsion products, application over insulations or cements containing soluble salts may show efflorescence or white scale deposits on the surface if water is present in the insulation. Efflorescence may be removed by normal rainfall or washing after mastic is dry but may recur if water continues to be present in the insulation.
• To resist rain washoff, allow at least 24 - 48 hours drying time above 60°F, with a relative humidity of 50%. Higher humidity or lower temperatures may retard drying.
• H.I. Mastics may dry and weather to a dark gray color.
• Outdoor horizontal surfaces must always drain completely.
• A pitch of at least 1/2 inch per foot (4 cm/m) is required.
• Not recommended for indoor use.
• Always test foil and paper facings for acceptable adhesion before using.

• Subject to type of surface being coated.
• Wet coverages shown below are for smooth non-porous surfaces.
• Porous or rough surfaces may require higher gallonage to attain required dry thickness.
• Dry Thickness: 0.112 in. (2.8 mm) to 0.123 in. (3.1 mm)
• Equivalent Wet Coverage: 0.25 in. (6.4 mm) 16 gallons per 100 sq. ft. (6.5 l/m²)

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. Cement coats must be dry. This product cannot be successfully applied by brush or spray.

Application - Outdoor and Heavy Duty Service 

• To prevent water infiltration, properly flash all penetrations.
• Prime dusty insulation or porous cements with an asphalt primer.

MAST-A-FAB® Reinforcement

• Apply tack coat of H.I. Mastic at 8 gal. per 100 sq. ft. (3.3 l/m²) by trowel.
• Embed MAST-A-FAB white membrane into the wet tack coat, Smooth membrane to avoid wrinkles and overlap all seams at least 2 inches (51 mm). Apply finish coat of H.I. Mastic at 8 gal. per 100 sq. ft. (3.3 l/m²). The second coat shall be applied immediately following the initial set of the first coat while it is still damp.
• This application shall provide a minimum dry film thickness of 128 mils (3.2 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 the dried mastic.

Trowel

• Apply evenly with a minimum of overworking of material. May be applied with a rubber glove on small radius pipes and vessels.

Clean Up

• Clean equipment with clean fresh water before mastic dries, followed by mineral spirits (flammable) or chlorinated solvent (non- flammable). Use mineral spirits or chlorinated solvent after mastic dries.