Gore-Tex
The GORE-TEX membrane is the heart of all GORE-TEX products. It contains over 1.4 billion microscopic pores per square cm (9 billion per inch). These pores are 20,000 times smaller than a water droplet, but 700 times larger than a water vapor molecule, which makes the GORE-TEX membrane completely waterproof from the outside, while allowing perspiration to escape from the inside. An oleophobic (or oil-hating) substance is integrated into the membrane, preventing the penetration of body oils and insect repellent that could otherwise affect the membrane. In order to meet the specific needs of each end use, W. L. Gore & Associates has developed different GORE-TEX membranes and applies them as appropriate.