Foster® C.I. Mastic® 60-25

• Foster® c.I. Mastic® is a tough, durable, high solids, vapor Retarder, asphalt cutback mastic.
• Because of its low vapor Permeance, it is an ideal surface coating for low temperature Insulation on outdoor applications.
• C.I. Mastic® may 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.
• C.I. Mastic® may be used as a solvent-based adhesive for asphaltic felt vapor retarder jackets on pipe and duct insulation.
• C.I. Mastic® meets the requirements for water proofing mastics in the tri-service specification for underground heat distribution conduit Systems.

• 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® 60 - 25  cannot be successfully applied by brush.
• Foster® 60 - 25 cannot be applied by spray.

• Prime dusty insulation or porous cements with 60-25 or 60-26 cut 50/50 with mineral spirits.
• Proper and complete flashing is required. Follow flashing specifications. If a decorative coating is to be used over the C.I. MASTIC®, allow a minimum of 30 days drying time before application.
• Outdoor and heavy duty service
  •  Apply a tack coat of Foster® C.I. MASTIC® at a thickness of 1/16 inch (1.6 mm).
  • This is equivalent to 4 gallons per 100 square feet (1.61 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 C.I. MASTIC® 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 the membrane.
  • This application shall provide a minimum dry film thickness of 123 mils (3.1 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.
• Spray
  • C.I. MASTIC® 60-26 may be airless spray applied using heavy duty pneumatic pumps.
  • Store 60-26 in a heated area. The material temperature should be at least 70°F (21°C) before spraying.
  • For spray equipment information, please consult Airless Spray Recommendations or contact your spray equipment supplier.
  • Average viscosity range: 100,000 – 150,000 cps.

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

• Store and apply between 40°F (4°C) and 100°F (38°C).
• Always test foil and paper facings for acceptable adhesion before using.
• C.I. MASTIC® may weather to a dark gray color.
• Outdoor horizontal surfaces must always drain completely.
• A pitch of at least 1/2” per foot (4 cm/m) is required.
• Always test plastic materials for compatibility when using a solvent-based product.
• Do not use on polystyrene foam.