View Full Version : Vapor barrier, extra warmth?

09-09-2008, 20:18
Hey, i have a WM Highlite 35 degree bag. I'd like to beef up the warmth in it for a trip in VT in October.

Options so far are a silk liner, but i'm wondering about the WM Hotsac VBL.. vapor barrier thing. Anyone have any experience with vapor barriers? Do they work? add some warmth?

09-09-2008, 20:39
I slip my Sierra Designs microlight rain pants on, over my shorts, and my jacket, along with two pairs of socks and a hat. This pushes my bag by 10 degrees as long as I'm out of the wind. The rain pants act as a vapor barrier on my legs ... I've also hiked in them, over a pair of shorts, down into the high 20's and been very comfortable.

I've also pushed a 40 degree sleeping bag well down below freezing with a thermolite bivy as a Vapor Barrier.

09-09-2008, 21:40
I tried sleeping naked in a vapor barrier as an experiment back in '89 or '90 when lots of people were talking it up.
I spent 2 very uncomfortable nights as you get very sweaty and clammy in there.

I was a little cold (put the VB inside my 20 deg. bag and slept out in aprox 10 deg temps) but not like i would freeze to death.

Then i discovered the old hot water bottle in your bag with you. Works much better, and it's a nice nights sleep and you can move that warmth around and well, i never tried the VB again. (but have used that hot water bottle Many many times since)

09-10-2008, 09:35
A lot of high altitude climbers like vapor barriers mainly to slow the loss of body moisture at altitude, since every drop they drink has to be melted from ice/snow and fuel has to be carried up the mountain to melt it. Vapor barrier socks do work well but macerated skin and trenchfoot are a consideration.