Made from wool that yaks shed naturally each spring, these base layers are even warmer than merino..
A good base layer is key to enjoying outdoor winter sports. Sitting right next to your skin, its job is moisture management – keeping you dry and therefore warm while you're getting sweaty on the slopes or trails. There are two kinds of base layers – natural and synthetic. The former has traditionally consisted of merino wool and silk, but now another interesting fabric is on the market and capturing rave reviews. It's made from Himalayan yak wool by a company called Kora.
Yak wool is similar to merino in that it comes from a shaggy animal that's used to rough outdoor living, but yak wool is even warmer and better at wicking moisture away from the skin because, as Kora explains, the yak itself lives in more extreme conditions and has evolved a cozier coat. Yaks live in the Himalayas at 5,000-6,000 meters above sea level and endure snow, ice, and hail all winter long, whereas merino sheep have a relatively comfy life at only 1,000 meters above sea level.
Kora, whose trademarked Hima-Layer fabric took three years of careful design and testing to create, says its pure yak fabric is 40 percent warmer, 66 percent more breathable, and 17 percent better at transporting water vapour away from the skin than merino.
A study conducted by Sheffield Hallam University’s Centre for Sport & Exercise Science looked at how different base layers maintained core body temperatures in people running at low temperatures. It found "the test subjects who wore yak wool lost an average of just -3.5˚C, compared to a -6˚C drop when wearing merino and -8˚C when wearing polyester."
After reading all this, I was curious to try it, so I packed a Shola 230 Zip top on a recent three-day ski trip to Jay Peak, Vermont, where the weather is notoriously windy and cold. For the first two days, when the temperature was -14C/6F, I wore the base layer with a light Patagonia down jacket and a shell. My core felt toasty warm. On the third day, which was equally as cold, I wore an all-synthetic base layer for comparison, but quickly realized I needed an additional fleece, in addition to my jacket and shell. Clearly the yak wool works.
Furthermore, it didn't smell at all after skiing. Once I got home, I didn't wash it, but simply hung it to air out. This isn't uncommon for yak, silk, and merino base layers; they are all naturally odor-resistant.
Kora sources most of its yak wool from nomadic herders on the Himalayan Plateau. Any additional wool comes from a network of local agents. From the website:
"Each spring, the yaks begin to lose their soft wool underlayer for the summer. The herders collect the loose wool (a painless process for the yaks) and bring it to market. Since 2012 we've worked with Kegawa Herders Cooperative, a group of more than 80 nomad families. We guarantee to buy all their wool at a premium, giving them an income they can rely on."
The pieces themselves have been designed by Piers Thomas, who has worked for Patagonia, Helly Hansen, and Rapha over the past 25 years.
The biggest downside of the Kora base layers is cost. This isn't cheap gear, with the tops starting around $125 and leggings at $145. There are bundled offers at slightly reduced prices; right now you can get 25% off certain bundles.
If you do spend a lot of time outside all winter long, however, this could be a worthwhile investment. I know I'm thoroughly impressed by its performance. Do I want more? Yes!
See Kora for more information.