Gore-tex patent

Gore-Tex is a waterproof/breathable fabric, used in a wide variety of applications such as high performance fabrics, medical implants, filter media, insulation for wires and cables, gaskets, and sealants.
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 a thin, porous fluoropolymer membrane in Teflon.

This membrane had about 1.4 billion pores per square centimeter. Each pore 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.

PATENTS:

Porous form of Polytetrafluoroethylene, Robert Gore, 1976

Waterproof laminate, Robert Gore, Rowena Taylor, Samuel Allen, 1980