Equalseal.com Expanded PTFE Joint Sealant is a soft, compressible gasket material made of 100% pure, expanded PTFE. It is a form-in-place gasket that conforms to almost any sealing surface. Upon compression, it forms a thin, hard ribbon that fills in surface irregularities and creates an extremely tight seal. It is capable of withstanding a wider range of pressures, temperatures and chemical environments than any other soft gasket.