Mastic No. 77 for Electrical Cable is a water base, fire retardant coating compounded from proprietary fire retardant resins, chemicals and non-asbestos reinforcing fibers. It has been designed for use on grouped electrical cables and their supporting trays. No. 77 prevents the propagation of fire along the cable surfaces, and substantially increases the fire endurance time of supporting trays.

No. 77 dries to a tough, hard finish with excellent abrasion resistance and good flexibility to withstand normal expansion and contraction, and is resistant to deterioration from flaking, impact, vibration and temperature changes. The coating will not dust, flake or spall. Spray application at 20.5 sq. ft./US results in an off-white, fine stucco-like finish.

Fire Tests:

Grouped cables were coated with Flame Control Mastic No. 77 to an average film thickness of 78 mils (1.98mm), 5/64 “, allowed to dry, and tested by a recognized testing laboratory according to requirements of The Institute of Electric and Electronic Engineers and were found to meet the requirements of:
  • IEEE-383-1974 Flame Test standard for Type Tests of Class IE Electrical Cables,Field\splices and connections for Nuclear Power Generating Stations, April 15, 1974
  • IEEE-45 Flammability Test, Recommended for Electrical Installations on Shipboard”, June 30, 1977

A test conducted by a qualified independent testing laboratory on the effect of coatings on ampacity, demonstrated a 0.8% electrical derating of cables coated with Mastic No. 77.


Lloyds Register of Shipping, Certificate No. Icd/F85/196 and American Bureau of Shipping, Certificate No. 85-C28913-X.