Tetratex - Proprietary Expanded Microporous PTFE (Polytetrafluoroethylene) Membrane Tetratex is a proprietary expanded microporous PTFE (Polytetrafluoroethylene) membrane, manufactured solely by Donaldson Membranes. It is laminated to a variety of base substrates to provide a REQUEST QUOTE Hansatech Instruments Ltd Distributor in SOUTH AFRICA