Gore-Tex — The Breathable Waterproof Membrane from Expanded PTFE

In 1969, Bob Gore — the son of Wilbert (Bill) Gore, founder of W.L. Gore & Associates — discovered that polytetrafluoroethylene (PTFE, the polymer better known by DuPont's trade name Teflon) could be stretched rapidly to create a microporous membrane with extraordinary properties. Gore found that when a rod of PTFE paste was heated and then yanked apart quickly — rather than stretched slowly — it expanded to over 800% of its original length without breaking, forming a white, microporous structure he called expanded PTFE (ePTFE). The membrane contained approximately 9 billion pores per square inch.

The critical discovery was in the pore size. Each pore in ePTFE is roughly 0.2 micrometers in diameter — about 20,000 times smaller than a raindrop but 700 times larger than a water vapor molecule. This size differential means the membrane blocks liquid water (rain, external moisture) while allowing water vapor (perspiration) to pass through. The membrane is also inherently hydrophobic: PTFE's fluorine atoms repel water, so even when rain is driven against the surface under pressure, liquid water cannot enter the pores.

Gore patented the ePTFE membrane in 1976 and launched the first Gore-Tex fabric laminates for outdoor clothing in 1978. The impact on outdoor recreation, military equipment, and workwear was transformative. Before Gore-Tex, waterproof garments were either impermeable (rubber, PVC-coated nylon — waterproof but trapped sweat) or permeable (waxed cotton — breathable but eventually leaked). Gore-Tex was the first material to be both waterproof and breathable — a combination that had been considered physically impossible. The technology extended beyond textiles to medical implants (vascular grafts), industrial filtration, and electronics insulation.