Waterproofness and Breathability explained

The simple reality is that making something waterproof is both super easy and super cheap. You need look no further than the humble—but utterly waterproof—plastic bag. Get a big bin liner, cut out holes for your arms and head, and voile! You’ll have a perfectly waterproof garment that will keep the rain out and that will, cost and weight-wise—outperform any jacket out there. Not keen on looking homeless? A plastic poncho will do the same thing.

However, once you start moving, your body heats up. Just as that waterproof bin liner stops rain getting in, it’ll also stop heat and sweat getting out. You’ll quickly feel like you’re in a portable sauna; soon you’ll be as wet as the rain would have made you, only now it’s from perspiration. Ick! But while I’m sure there are a few Wild readers out there who subscribe to the bin-liner raincoat/portable sauna solution, for the rest of us who actually want to stay dry, we need something that’s not just waterproof but breathable as well. And therein lies the rub: In one direction, you want to stop water (in its liquid form) from coming in; in the other direction, you want to let water (in its vapour form) out.

Waterproof/breathable fabrics were first introduced to the outdoor apparel market in 1978, when Gore-Tex introduced their first jacket with laminate technology. Since then, Gore-Tex has become synonymous with waterproof gear. But it’s worth remembering Gore-tex is actually a proprietary material. Many of us refer to our “Gore-Tex jacket”, when in fact it’s actually not made from Gore-Tex at all, but instead