Material Talk - Episode 1: What is Gore-Tex / ePTFE

What is Gore-Tex or ePTFE

Gore-Tex was created in 1969 by Bob Gore by heating and expanding polytetrafluoroethylene also known by it’s trade name Teflon. This new material was dubbed expanded polytetrafluoroethylene or ePTFE and is used extensively in Durable Water-repellent Membranes. DWR membranes feature ePTFE bonded to a face fabric like Nylon or Polyester.

Absorption and Drying speed

ePTFE pores are approximately 20,000 times smaller than a drop of water, however they are 700 times bigger than a molecule of moisture vapor.

This material is naturally hydrophobic, but relies heavily on the difference in relative humidity to transfer moisture vapor through the membrane.

Heat Retention

ePTFE has good heat retention properties, however it is most useful in preventing heat dissipation through convection by keeping liquid water away from your skin

Environmental concerns

It is a thermoplastic created from chloroform, which is largely produced by seaweed within the atmosphere. Thermoplastics do tend to liquefy, which allows them to be easily injection molded and then subsequently recycled. When heated above 280°C, PTFE breaks down to release hydrogen fluoride, carbon fluoride, carbon monoxide, and other pyrolysis products, particularly fluoropolymers of low molecular weight

Use in Garments

In the river world this material is most commonly found in drysuits, drytops and paddle jackets. It is not actually the fabric you see and this is a common misconception in the outdoor world due to the general marketing language used by manufacturers.

ePTFE is often used as a 2 or 3 layer system. 2 layer systems have the face fabric bonded to a layer of ePTFE while the 3 layer design sandwiches the ePTFE between 2 layers of Face fabric.

Studies have shown that PTFE will degrade in the presence of water and metals like (gold, copper, zinc, silver, and iron) so equipment that integrates PTFE should be dried thoroughly to avoid degradation.