Warmlite Shirt test Feb 25, 2011
Vapor Barrier Shirt
Snow swirled around me as I began walking up a 3,000 ft Big Sur mountain. Snow is rare enough in Big Sur, but even less common was the type of shirt I was testing.
Its called a Vapor Barrier Shirt, no thicker than a dress shirt, from a clever firm called Warmlite. While walking uphill starting about 500 feet above sea level (ASL), the air temperature could not have been warmer than 32 degrees F as snow landed on me.
After about two hours, when a chilly breeze started and the snow stopped falling, I put a standard hooded sweatshirt over the Warmlite shirt. Amazingly, that was all I needed to keep warm – all day.
Climbing the mountain, eventually I was sweating enough that perspiration ran off in tiny streams – more than mere drips. Oddly – my wrists were sweating.
I was wet under the shirt, BUT I wasn’t getting cold ! My body stayed warm all day even though the outside temperature was in the low 30’s (maybe even in the twenties) with only the Warmlite shirt and then later a normal sweatshirt with a hood over it. I learned a new concept: wet is different than cold.
You can be wet inside that shirt (not everyone’s cup of tea), but remain warm ! Kind of amazing. (Later I learned the correct way to use it is to loosen the neck and cuff when you start to sweat – so the sweat doesn’t even get started.)
Snow Cloud V-beam
But by far, the most amazing phenomena was that this thin jacket (dress shirt thinness actually) could keep me so warm.
I did put on a down jacket for descent because going downhill, I wasn’t generating much internal heat. That day was spectacular for photography and unforgettable for the exciting new (to me) camping technology.
Works at home too ! Excited about how well that shirt worked in snow, I’ve since tried it at home when seeing how much energy I could save in winter. When I would first feel cold, I’d put the Warmlite shirt on and instantly (not 3 minutes later, but as soon as I zipped it up) would feel 10-15 degrees warmer !
That did it. The shirt now goes with me on every hike, bike, skiing, camping, boat or plane trip as an emergency item along with a the requisite Swiss army knife, matches, emergency mylar tent, straw, and dental floss. I packed it for my entry in the Race to Alaska.
You can find the shirts at Warmlite in New Hampshire, founded in 1955. Their whole camping line of equipment is designed by a former NASA engineer. Here’s an article explaining how it works. and their NSFW catalog