Maybe you've worn a bad raincoat before. You might not get wet from the rain, but it turns into a dirty sweat coat after a little walk. That's because the raincoat doesn't breathe properly.
Now you can poke several holes in the raincoat, but then it no longer protects you against rain. You need one-way holes. "It seems impossible," says Wiebe de Vos, "but it can be done with a membrane!"
Want to discover exactly how membranes stop rain but let your sweat pass through? Then watch this episode of 'Legt Uit' from the University of the Netherlands.
