81 Modified Bitumen Adhesive

    81 Modified Bitumen Adhesive

    Available in: 5 gallon pails & 55 gallon drums
    KARNAK 81 Modified Bitumen Adhesive is a premium cold-applied, high strength SBS polymer modified asphalt adhesive, that provides excellent adhesion and elongation properties.



    • UL approved
    • Eliminates the need for torches and kettles
    • Excellent cure
    • Tough, flexible, adhesive and cohesive film
    • Excellent water and weather resistance
    • Excellent general adhesive
    • Excellent lap cement
    • Good U.V. resistance
    • Easy to apply
    • Elastomeric, moves with substrate
    • VOC: 293 g/L

    Coverage Calculator

    • 1-2 Gallons per 100sf**


    This is intended as a general guideline only, coverage can vary based on many factors.


    KARNAK 81 Brush-Grade is used to adhere SBS modified bitumen membranes, base and ply sheets. KARNAK 81 Modified Bitumen Adhesive can also be utilized to adhere conventional BUR ply sheets or fully granulated cap sheets. KARNAK 81 Trowel-Grade can be used to make repairs on existing modified applications and flashings on vertical surfaces, i.e. skylights, vents and pipes.

    Physical Properties

    Weight per Gallon:                 8.65
    Shear Strength:                       26 lbs./sq. in.
    Peel Strength:                          13 lbs./lin. in.
    Elongation:                              250%
    Recovery:                                 95%
    Set Time:                                  24 to 48 hours
    Dry Time:                                 Approximately 30 days
    Application Temperatures:  40ºF to 100ºF

    Preparation & Application

    All surfaces should be free from oil, grease, dirt and loose materials. All BUR surfaces should be patched and repaired with KARNAK 19 Ultra Rubberized Flashing Cement and KARNAK 31 Glass Membrane. Metal surfaces must have all rust and scales removed.

    Apply KARNAK 81 Modified Bitumen Adhesive Brush Grade at the rate of 1 to 2 gallons per 100 square feet on horizontal surfaces; irregular surfaces will require 2 gallons per 100 sq ft. On vertical surfaces apply KARNAK 81 Modified Bitumen Adhesive Trowel Grade at 1/8” thickness (approx. 8 gallons per 100 sq. feet.) KARNAK 81 Modified Bitumen Adhesive may be applied by squeegee, roller, brush or trowel. Allow an open time of 15-20 minutes before placing membrane into adhesive.

    Caution/Care of Tools

    Do not use near open flame. Avoid breathing solvent fumes and prolonged contact with skin. Excessive application may create blistering. Application below 40°F may take longer to cure. Do not take internally. If swallowed, do not induce vomiting. Call a physician immediately. Keep out of reach of children. Keep container covered when not in use. Do not thin. Dispose of in an environmentally safe manner. Cover air intakes during application and while drying.

    Equipment may be thoroughly cleaned after use with mineral sprits or Karna-Klean taking necessary precaution when handling combustible materials.

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