Fiberglass is used for making tape because it resists high temperatures. Fiberglass tape is one of the few products when ‘tape’ can refer to both tape with adhesive and tape without adhesive.  Fiberglass tape without adhesive refers to a braided, flexible strip of fiberglass.  This type of tape is used to wrap pipe, hoses and cables for use at extremely high temperatures.  Also used as door seals and flange gaskets, fiberglass tapes without adhesive can withstand temperatures up to 1000ºF (538ºC).  Fiberglass cloth tapes with adhesive are limited to a maximum use temperature of 500ºF (260ºC).

 Fiberglass cloth tapes are a type of electrical tape where the glass-cloth fabric offers resistance to abrasion and mechanical strength as well as high dielectric strength.  Standard UL recognized tapes use thermosetting rubber adhesive (130ºC class), acrylic adhesive (155 ºC class) or silicone adhesive (180ºC class).

PTFE coated glass-cloth tapes combine the abrasion resistance  and mechanical strength of glass-cloth fabric with the release characteristics of PTFE, polytetrafluoroethylene.  The PTFE top coating reduces the surface energy of the tape and provides a quick release surface that is inherently resistant to chemicals.  Some people refer to PTFE by the trade name of Teflon which was invented by accident in 1938 and became a trade mark in 1944.  In 1950 DuPont purchased the Teflon trade mark.

Because PTFE coated fiberglass tapes withstand high temperatures and have a slick, easy release surface, they function very well as a Heat Seal Tape in the production of polyethylene bags and for heat sealing polyethylene bags after they are filled with product.