Abstract: The present invention includes bodies of flexible expanded graphite or of rigid body porous graphite impregnated with blended polymer-wax treatments to create composite bodies that exhibit properties critical in the function of electrochemical systems, and methods of manufacturing the same. High electrical conductivity is an inherent attribute of the untreated graphitic material that is retained through the impregnation process, while attributes of extremely low permeability and high mechanical strength are added to the composite via the polymer-wax blend. In one embodiment of the invention, the attributes of low ionic permeability, high flexural strength, and high electrical conductivity are achieved to create a component that could be useful in Redox Flow Battery (RFB) systems.