Water Repellents

 water resistant fabric where water droplets bounce off without clinging to the surface. AATCC Test Method 22 is used to rate this quality. The better the spray rating, the less water clings to the fabric surface. When the term waterproof is used, the fabric must also resist the passage of water through it. The ability of water to pass through is a function of the number and size of pores and openings. For example, DWR-finished tightly constructed fabrics, such as poplins, are more waterproof than are more open-weave fabrics even though the spray ratings may be the same.