TECHNOLOGY WATERPROOFNESS & BREATHABILITY The waterproof/breathability of fabrics is typically describes with two numbers. The first is in millimeter (mm) and is a measure of how waterproof a fabric is. In the case of a 20k or 20,000mm fabric, if you put a square tube with inner dimension of 1”x1” over a piece of said fabric, you can fill it with water to a height of 10,000mm before water would begin to leak through. The higher the number, the more waterproof the fabric. The second number is a measure of how breathable the fabric is, it’s normally expressed in terms of how many grams of water vapor can pass through a square meter of the fabric from the inside to the outside in a period of 24b hours. In the case of a 20k fabric, this would be 20,000 grams. The larger the number, the more breathable the fabric.
WATERPROOF RATING Waterproof rating (mm) 0-5,000 6,000-10,000 11,000-15,000 16,000-20,000 20,000 +
Resistance provided No resistance to some resistance to moisture Rainproof and waterproof under light pressure Rainproof and waterproof except under high pressure Rainproof and waterproof under high pressure Rainproof and waterproof under very high pressure
What is can withstand Light rain, dry snow, no pressure Light rain, average snow, light pressure Moderate rain, average snow, light pressure Heavy rain, wet snow, some pressure Heavy rain, wet snow, high pressure
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