Ski mountaineering, ski touring, or backcountry skiing are more of a highly active pursuit than say resort skiing–you need to use your own power to get uphill. This means sweat and sweaty feet equal cold feet. To combat clammy, cold feet at the end of the day, Gore-Tex teamed up with top ski mountaineering boot manufacturers to create more breathable liners for those that earn their turns.
Most ski boot liners today are made from a specially formulated thermo-forming closed cell EVA foam. This foam consists of millions of tiny cells, or bubbles, which when heat-molded into a specific shape, retain their form until reheated.
This makes for great custom fitting boots that won’t pack out over time, but the liners are neither waterproof nor breathable. So as you work up a sweat skinning uphill, you just end up with wet and cold feet at the end of the day, as the sweat has no place to go.
The solution for both Scott and Dynafit is to create a liner that uses a combination of Gore-Tex waterproof breathable laminates and perforations in the thermo-moldable foam. This unique construction lets water vapor escape throughout the day as your feet get hot and sweat.
This water vapor can not get back inside the liner because of the Gore-Tex membrane, but instead will remain inside the plastic shell of your ski boot until your remove your liners and let your boots dry at the end of the day. Now you get the best of both worlds–a high breathability ski boot liner with a custom fit.
In the Dynafit Winter Guide GTX, the boot liner uses multiple perforations across the liner, while in the Scott Superguide Carbon and Orbit II Carbon, breathable patterns are featured in certain sections. Keep an eye out for these breathable ski mountaineering boots next winter.