our fabric is 20,000mm waterproof. what does that really mean? keep reading.
what does the waterproof rating really mean?
there is a huge misconception about millimeters of water-proofing and breathability. the way the rating system is used is a total scam, and people unfortunately end up playing into a huge marketing scheme of companies all trying to outdo each other with tech talk.
how do they get those numbers? well, they take a swatch of fabric, turn it upside down (outside face down) and clamp it to a bowl. The bottom of the bowl has a tube, which runs up to a bucket that is filled with water. the bucket is then raised into the air, and the height (in millimeters) that the bucket reaches when water begins to force itself through the fabric is the mm of waterproofing.
so, even from the beginning of the test, the fabric is not only completely saturated with water, but then the increasing pressure of the raising bucket adds many times the force of gravity to the already completely saturated fabric (because a large amount of water is pressuring a small surface area of fabric). any fabric that can withstand the beginning of this test (zero to a few hundred mm) is waterproof enough for most kinds of outdoor use.
generally, waterproofing naturally increases as the quality of the fabric increases. the fabrics that are above a few thousand mm waterproof tend to be woven more tightly. some of the most technical fabric in the world is quite thin, but when your 40k mm jacket gets a hole in it, it's not very water proof anymore! other things that play a big role are: type of fabric, construction, various coatings, seam seals and tape, lining, etc.
because of all of these factors, First Drop continues to search out what we would consider the “perfect” fabric. for 2010/2011 we choose a very thick, durable, 20k waterproof/ breathable, nylon-taslon shell with a breathable medium weight poly-fill liner and a mixture of inner liner fabrics including taffeta, breathable mesh, and fleece. we feel this construction is the best fabric for our purposes, and we have personally tested the suits in full winter blizzards and rainstorms. they preformed flawlessly.
TM