The use of polyester mat as a backer provides wetting action during VPI resin treatment for a strong layer-to-layer bond after subsequent resin cure. The woven glass reinforcement provides high tensile strength and optimum flexibility. The PET mat improves handling characteristics and provides good resin flow during processing. Mica Mat 77944 tape is a 7.5 Mil three-ply epoxy bonded mica paper tape designed for vacuum pressure impregnation processing. The 4 Mil calcined mica paper has glass cloth on one side and a PET mat on the other. The resin binder in this tape was selected to be compatible with a wide variety of solventless polyester and epoxy VPI resins.