Gore Tex Membrane
Goretex is a name of a membrane, which is resistible against water, and in the same run breathable.
The gore tex membrane was invented in 1969 by the American chemist Robert W. Gore. The goretex textiles could be bought for the first time in 1976 and they where the first of their kind (waterproof, windproof and breathable). The membrane works like this: The membranes pores are about 20,000 times smaller then a water droplet, what makes them impermeable to liquid water. But the pores are big enough to let through the vapor of the human perspiration, because the molecules of water vapor are smaller then the ones of liquid water. This makes the membrane perfect for waterproofing on textiles. But it is also used for other purposes such as filters, bikes, insulation for cables and you can also find it in medical systems.
One disadvantage of the Gore Tex membrane is that it only works when the difference between the outer and inner temperature is high enough, so that the osmotic pressure is high enough. That means if the outside temperature is above 15-18 °C the gore tex membrane will stop being breathable, which makes you sweat. But that’s not much of a big problem, because at temperatures like these, you won’t need a jacket, if you are not working in wet areas or if it it’s raining in the summer. There are also no other fabrics which perform better then Goretex.