What Is The Working Principle Of Waterproof Fabric?

In the state of water vapor, the water particles are very small. According to the principle of capillary movement, they can smoothly penetrate into the capillary tube to the other side, thus causing vapor permeability. When water vapor condenses into water droplets, the particles become larger. Due to the surface tension of the water droplets (the water molecules "pull and compete" with each other), the water molecules cannot smoothly break away from the water droplets and penetrate to the other side, which is to prevent Water penetration occurs, making the breathable membrane waterproof.