For the Thermoball jacket, The North Face employed a synthetic insulation technology with the warmth equivalent of 600-fill goose down. But unlike down, it is hydrophobic, ie, it sheds water and functions well when wet. It is also ultralight, highly packable and bluesign-approved. The Thermoball technology features round clusters that trap and retain heat in cold and wet weather.
The insulation is designed to act like down feathers, keeping warm air pockets rather than clumping. Triangular baffles maintain the loft.
This technology came about after mountaineer Conrad Anker and his partners on the North Face climbing team aborted an attempt to climb Mount Meru in India’s Garhwal Himalaya. “We spent two years developing new products that would help us do better on the next attempt,” Anker told Popular Science. “Thermoball was one of those products.”
Anker and team returned to Meru in 2011 with prototype Thermoball jackets. “Having the Thermoball jacket on Meru on our second attempt this fall provided mental comfort,” said Anker. “We didn’t have to worry about our jackets getting wet. When there are three guys sleeping in a portaledge, there is condensation. We slept in these jackets as well as wearing them when we were climbing as part of a five layer system. And they did the job.” Jimmy Chin, Renan Ozturk and Anker climbed the central pillar of Mount Meru, summiting at 20,700 feet.
Non-mountaineers will find plenty to love in this jacket. It never hurts to be over-prepared, especially when your jacket is so light and hand-pocket–stowable. In previous years we’d resorted to wearing a rain-protective shell overtop of the down layer, but the Thermoball has happily cancelled out the need for that bulky setup.