GORE-TEX® – how this waterproof membrane works

The US researcher Bill Gore developed GORE-TEX® in 1969 – and, as with so many other inventions, this innovation came about by chance. His son was tinkering around in the cellar with polytetrafluoroethylene, or PTFE for short, a special polymer. He stretched the material out to create the new membrane ePTFE, which had striking properties: it was both breathable and waterproof. 

ePTFE works because this material is highly porous, full of tiny little openings. The size of these billions of pores is key: they’re 20,000 times smaller than the smallest droplets of water, which prevents rain from getting through the membrane. But that’s not all: they’re also 700 times bigger than water vapour molecules, so these can easily pass through the membrane to the outside. In short, vapour can get out but rain can’t get in. 

You can’t wear the ePTFE membrane on its own, though: it’s too thin and susceptible to being torn. Mechanical abrasion would quickly destroy it. That’s why the GORE-TEX® is glued to another material inside your clothing, without this inhibiting GORE-TEX®’s properties. 

Two-layer and three-layer jackets differ in terms of their inner lining. Two-layer jackets have a loose inner lining that’s not glued down. Conversely, three-layered jackets feature an inner lining that’s firmly glued to the membrane and outer layer. Models with three layers are a bit heavier, but they’re also more robust. 

If you want your GORE-TEX® clothing to stay waterproof and breathable for as long as possible, the right care is important. Here are two tips: 

Wash it regularly
It’s not true that you shouldn’t wash your GORE-TEX® clothing often. Quite the opposite, in fact: wash your waterproof clothing regularly. This removes dirt and sweat from the membrane so water vapour can pass through again. You should also waterproof your GORE-TEX® products, which helps them keep their properties as long as possible.

How frequently you should wash your outdoor clothing depends on how often you wear it. As a rule of thumb, you should wash it after 10 to 20 days of heavy use, or 20 to 30 days of lighter use.

Use the right combination
If you only wear absorbent materials, like cotton, under your GORE-TEX® jacket, the membrane can’t function to its fullest effect. Why? Because the water vapour is soaked up before it gets to the jacket. That’s why you should wear high-performance items, such as garments made from merino wool or breathable synthetic fibres, under your GORE-TEX® clothing. These materials wick moisture away from your body, thereby supporting the properties of your jacket. If that doesn’t keep you warm enough, you can wear a fleece as a second layer.

Water-repellent, water-resistant, waterproof: the terminology associated with outdoor clothing can get a bit confusing! GORE-TEX® products are permanently waterproof, with a water column of at least 28,000 millimetres. In other words, you could put a 28-metre column filled with water on top of the material – and only then would water get through. 

GORE-TEX® wants even more precise information, though. That’s why all their products are subjected to a rain test. In this, various weather situation – from light drizzle to heavy downpours – are simulated in a rain tower. The products need to pass this test, whether they’ve just left the factory or whether they’ve been used for ages. 

Maybe a spark flew off a fire onto your jacket or you snagged it on a piece of barbed wire. Holes like this are annoying – but no reason to throw your jacket in the bin. We’ll repair your GORE-TEX® clothing so it’s totally waterproof again.

Water vapour permeability is colloquially known as breathability. With a breathable fabric, water vapour can escape from the inside to the outside. This keeps the body as dry as possible, even during strenuous exertion. Breathable materials include membranes such as GORE-TEX®, but clothing made from merino wool and synthetic fiber also has good breathability.