Microporous membrane technology
The Obermeyer HydroBlock® Series is a system of waterproof breathable coatings. Waterproof ratings are determined by an independent third-party laboratory.
Waterproof breathable fabrics consist of an outer layer called the “face fabric”, usually made of nylon or polyester, and a laminated polyurethane membrane or coating. The purpose of the face fabric is to protect and look stylish. It is finished with the latest DWR polymer coating. The DWR is a protective layer to keep the fabric from getting soiled and thereby losing some of its technical characteristics for breathability and water resistance.
The job of keeping the water out is left to the membrane, which has tiny holes too small to let liquid water enter but large enough to allow water vapor to escape. Since contamination with oil, sweat and chemicals can cause PTFE membranes to lose their ability to keep out water, the membrane is protected by an ultra-thin layer of Polyurethane. Modern waterproof breathable fabrics are more sophisticated than ever and most are exceptionally waterproof at any price point with recent incremental gains in breathability redefining high exertion outerwear.