This is Gore-Tex, the magical material used to make expensive waterproof jackets!

Actually, it's not ONE material, but a whole series of different fabric layers with specific specifications. Their common denominator is a specific form of polytetrafluoroethylene (try saying that 3 times fast!), PTFE or Teflon for friends.

What's so amazing about this material? It allows water vapor to pass through it, but blocks liquid water. In other words, it's waterproof AND breathable!

Doesn't that sound amazing to you? Try wearing a nylon bag. You may not get wet from the rainwater, but in a few minutes you'll be soaked from your own sweat!

The inventors of Gore-Tex were William and Robert Gore, father and son. The myth says that the discovery was made by accident, thanks to the son's sensitive nerves. Frustrated by previous failures with PTFE, he forcefully stretched the material.

The result was this plastic stretching 8 times but also acquiring these magical properties. At a microscopic level, with this distortion, the structure of the material changed, forming crystalline regions.

This is why the manufacturers of Gore-Tex jackets tell you not to expose them to high temperatures: heat restores the microscopic structure of the material to its original state...