A new process was invented for preparing an improved polytetrafluoroethylene (PTFE) sealant material from a paste formed of PTFE resin with special plasticizer. This expanded PTFE sealant material consisted of a special node and fibrous microstructure. The preferred orientation for mechanical strength of the fibrous structure was parallel to the direction of calendering. The expanded PTFE material was investigated for its mechanical properties. including creep relaxation, compressibility. recovery, torque retention, and gas permeability, as defined by the ASTM and DIN standards. The sealing performance of the material was further characterized by the room temperature tightness test established by the Pressure Vessel Research Council (PVRC). The test results suggest that uni-axially expanded PTFE is soft and compressible, with excellent sealability. it is strong, possessing good resistance against creep and cold-flow. These favorable properties of expanded PTFE, as compared to traditional PTFE-based gasket types, make it a promising gasket material for fluid sealing applications.