Current outdoor clothing marketing has led us to believe that wet is cold. Companies tout ‘breathable’ clothing as the way forward, and ‘wicking’ being a necessity in the cold.
But ask cold weather aficionados (be it a hunter, runner, or cyclist) and many of them claim that wet is better, as long as insulating layers stay dry.
The buzz-word is ‘vapor barrier’ and the concept is simple, if counterintuitive: wear water-proof clothing next to the skin and keep the sweat in next to the skin instead of allowing it to evaporate.
It’s an indisputable fact that the body is going to sweat during physical exertion and clothing is going to get wet. It’s when this sweat is wicked off the surrounding clothing that body temperature drops.
Imagine standing in 50-degree weather and being perfectly comfortable and then standing in 50-degree weather after just getting out of a pool and freezing. The concept is the same.
Instead of allowing the sweat to saturate insulating layers, vapor barrier clothing prevents the sweat from evaporating, thereby preventing evaporative cooling on the body.
Vapor barrier clothing can range from something as simple as plastic bags underneath warm socks and a garbage bag over the torso, to lightweight and durable vapor barrier clothing that will hold up to the rigors of time.
Full vapor barrier outfits can be purchased, including jackets, vests, socks, gloves, and pants. Any amount of insulation can be added on top of the vapor barrier layer. These layers will keep heat close to the body without the added worry of getting the crucial insulation wet.
To stay comfortable with a vapor barrier setup, sweating does need to be regulated to avoid excessive pooling of sweat. Therefore, this set-up is most effective for people engaging in steady, aerobic activity at very low temperatures.