How does waterproof and windproof clothing work?
Waterproof/breathable fabrics resist water droplets from passing through while at the same time allowing water vapour through. Their ability to block out rain and snow while allowing vapour from sweat to evaporate lends to their use in outdoor sports clothing (i.e. a raincoat) and single-wall tents Standard laboratory testing protocols define the performance of these fabrics. Water resistance is measured by the amount of water, in mm, which can be suspended above the fabric before water seeps through. Breathability is measured by the rate at which water vapor passes through, in the units of grams of water vapour per square meter of fabric per 24 hour period (g/m2/d), often abbreviated to just “g”. In recent years, some, but not all sporting goods manufacturers have begun including this information on their product labels. Typical mid-range fabrics tend to have values of 5,000 mm of water resistance and 5,000 g of breathability; the highest end materials boast 20,000 mm and 20,000 g. On
