Gear Guy

Will a vapor barrier liner keep me warm and dry?

Because I sweat at a moderate activity level in cold temperatures, my insulation gets dp and looses it effectiveness. Layering and reducing exertion does not eliminate the problem. I a human fire hydrant. I have heard that vapor barriers could really help. Any suggestions on what to look for and brands? Ed Eugene, Oregon

A: No! No vapor barrier liner!! That would be very bad for you. As most readers know, vapor barrier liners (VBLs) can be useful in very cold weather. They're made of coated, waterproof, non-breathable fabric, and keep the user warmer by blocking evaporative cooling. In most cases, they're used as oversocks or sleeping bag liners. Use one as clothing? NO! For one thing you'd probably croak from dehydration. For another, you'd get completely soaked, as the VBL will greatly amplify sweating. Changing clothes in cold temperatures would be a life-endangering feat, with the risk you'd be coated in ice before you got something else on.

Better to manage the problem, rather than beat it to death, which is the VBL approach. For one thing, sweating is caused by over-heating. You say you've worked with layering, but if you're still warm or too warm, keep peeling until you're comfortably cool. If it's around ten degrees, for instance, and you're working moderately hard, a lightweight long-sleeve top like a Patagonia Capilene Zip T ($34) should be fine. Otherwise, look for new-generation fabrics that do a good job of wicking. Polartec Power Dry works very well—REI puts it in a zip T called the...Power Dry Zip T (wow, original!) for $36. For an insulating layer, some of the new Polartec fabrics such as PowerShield breathe well while wicking like mad. Arc'Teryx's Gamma SV Jacket ($240) uses it. These fabrics also dry very quickly, so once they're wet from sweat they don't take too long to lose moisture.

You may have to experiment a little. But, I'd definitely stay away from the VBL. It's not the way to go.

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