Foster® 95-90™ (light consistency) Vapor-Safe® Mastic is a fire resistive, fibrated, water-based, vapor barrier sealant for indoor or outdoor low, medium and high velocity heating and air conditioning ducts. It performs as a tough and flexible adhesive and sealant, forming a durable seal against air leakage when used with reinforcing membrane. Mechanical fasteners of the type and number normally used for duct assemblies are required to provide rigidity to the duct system.
VAPOR-SAFE DUCT CLOSURE MASTIC is ideal for vapor sealing ASJ, FRK, and FSK jackets and board facings at joints, laps, and over staple and weld pin punctures. VAPOR-SAFE DUCT CLOSURE MASTIC meets NFPA 90A and 90B requirements.