Gore-Tex is a waterproof/breathable fabric, and a registered trademark of W.L. Gore & Associates. It was co-invented by Wilbert L. Gore (1912-1986), Rowena Taylor, and Gore’s son, Robert W. Gore for use in space. Robert Gore was granted U.S. Patent 3,953,566 on April 27, 1976, for a porous form of polytetrafluoroethylene with a micro-structure characterized by nodes interconnected by fibrils. Robert Gore, Rowena Taylor, and Samuel Allen were granted U.S. Patent 4,194,041 on March 18, 1980 for a “waterproof laminate.” For its invention, Robert W. Gore was inducted into the National Inventors Hall of Fame in 2006.
Gore-Tex is manufactured from polytetrafluoroethylene (PTFE). PTFE is made using an emulsion polymerization process that utilizes the fluorosurfactant PFOA, a persistent environmental contaminant. As Gore-Tex is PTFE-based, PFOA is used in its production.
Gore-Tex materials are typically based on thermo-mechanically expanded polytetrafluoroethylene (PTFE) and other fluoropolymer products. They are used in a wide variety of applications such as high performance fabrics, medical implants, filter media, insulation for wires and cables, gaskets, and sealants. However, Gore-Tex is best known for its use in protective, yet breathable, rain wear.
The simplest sort of rain wear is a two layer sandwich. The outer layer is typically nylon or polyester and provides strength. The inner one is polyurethane, aka PU, and provides water resistance, at the cost of breathability.
Early Gore-Tex fabric replaced the inner layer of PU with a thin, porous fluoropolymer membrane (Teflon) with a polyurethane coating that is bonded to a fabric, usually nylon or polyester. This membrane had about 9 billion pores per square inch (around 1.4 billion pores per square centimeter), each of which is approximately 1/20,000 the size of a water droplet, making it impenetrable to liquid water while still allowing the smaller sized water vapour molecules to pass through.
However it was found that when used in clothing the exposed Teflon membrane layer was easily damaged, as well as being compromised by exposure to the wearer’s own sweat. As a result a third layer was added - a coating of PU on the inside of the fabric to protect the membrane. This final design has been criticized as offering greatly reduced performance and more marketing benefits than performance ones.
More recent fabrics such as eVent and Epic avoid the need for this inner PU coating and have been shown to have higher breathability as a result, while still being rainproof.