In order to overcome some of the setbacks of the solid polymerized Teflon, gaskets have been produced to take advantage of the resilience of asbestos, rubber and other like materials. In modified gaskets, the resilient material is usually surrounded by a thin envelope or layer of polymerized Teflon material. These composite gaskets have the chemical resistance of Teflon in addition to the resilience of the filler material.
Another means used to overcome the challenge of solid Teflon gaskets is making sure the spring loading of stuffing boxes are able to accommodate the high thermal expansion of Teflon, and the spring loading of gasket joints. All these gaskets are expensive in cost and in addition to that, they do not provide the uniform resiliency of a true gasketing material.
Woven cloth of sintered glass fibers has also been induced with an aqueous dispersion of Teflon solids and used as a gasketing material. However, this material has a drawback in the sense that it is somewhat brittle and will not stand excessive flexing. In addition, cutting gaskets from such a material produces weaknesses and tagged edges. Such gaskets are further limited in thickness to the thickness of the glass strands unless laminates are made. They also lack the resilience necessary for good gasketing action.
Polytetrafluoroethylene fibers are felted and induced with Teflon resin to produce gasketing materials essentially composed entirely of Teflon. Gaskets of this material are subject to cold flow under pressure, somewhat similar to rubber, and are therefore unsatisfactory for this reason.