Insulating Mastics

Plyfill ®

Plyfill is a self-amalgamating low voltage insulating mastic, designed for quick void-free insulation build-up.

Plyfill can be easily molded by hand to confirm to irregular shapes and can be used as primary insulation for splices through 5 kV in conjunction with other insulating tapes. Plyfill provides an excellent moisture seal.


A self-amalgamating, mechanical grade mastic used for sealing and water-proofing. Excellent adhesion to metals, cable insulations, and jackets. Soft, malleable nature makes Waterseal ideal for molding and conforming to irregular shapes. Use in conjunction with Plymouth’s premium tapes for optimum performance.

Rubber Mastic (RM) ®

A self-bonding mastic tape consisting of an ethylene propylene rubber (EPR) backing, bonded to a tacky, temperature stable, electrical grade mastic. Use for insulating and moisture sealing splices and terminations on solid dielectric cable. Can be wrapped, stretched or molded around irregular shapes for insulation build-up, water-sealing, and surface protection.

Provides excellent electrical properties, superior adhesion, moisture and chemical resistance. For primary insulation up to 2kV.

Vinyl Mastic (VM) ®

A self-fusing mastic compound with an all-weather, premium vinyl backing that can be used for insulating and water-sealing electrical connections through 600 volts. Small roll sizes can be stretched and molded around irregular shapes, even in tight locations.

Provides excellent electrical proper-ties, superior adhesion, and moisture and chemical resistance. Vinyl backing adds UV protection. Use for insulating overhead and direct buried low voltage connections, motor lead connections, and cable and conduit repair.


A self-amalgamating, insulating mastic for insulating and sealing all types of overhead and direct buried electrical connections up to 600 Volts. 10 Plyseal has superior adhesion to metals, cable insulations, and jackets with no adverse effect on polymeric conducting shields. For watersealing duct work, cable ends, and all types of splices.

5000 PLYSEAL ®

A laminate of W963 Plysafe EPR high voltage tape and 10 Plyseal insulating mastic in a roll form. A one-pass application of this laminate provides high dielectric strength, instant adhesion and excellent conformability.

For insulating and water-proofing high voltage bus connectors and conductors. Corrosion protection for junction boxes, bus-duct and cable tray joints.