Vapor Barrier experimentation
I have been reading the vapor barrier discussions both past and present with a morbid fascination. When I first came across it my thoughts were “What kind of idiot wears a sweat suit in the winter?” Yet, as my reading continued there were nuggets of information that slowly sunk in. BillyBob58 is nothing if not persistent. There was anecdotal evidence, there was use of VB’s by Andrew Skurka. Maybe I was missing something.
Finally while reading this thread it finally sunk in. It is the evaporative cooling element that got me to thinking this could work. Sure, containing the moisture keeps your insulation dry, but what I saw as a great value was stopping evaporative cooling. I think the reason it took so long to understand this was that I never thought of evaporative cooling in a cold environment. But the laws of physics do not suspend there self just because it gets cold.
Since we had a nice cold front rolling in, tonight was the night to test the theory. Since no sane person actually owns vapor barrier clothing, I made due with Frogg Toggs top and bottom. My base layer was LL Bean long silk underwear, then the Frogg Toggs. I wore a cotton/polyester blend cargo pants, an 80% wool sweater from Goodwill, and a Gerry 650 fill down puffy. On my feet I decided that since I have two of them, I can conduct a controlled test. On my right foot I wore a Shower Pass waterproof sock with a Heavy Wigwam wool sock over that. On the left foot was a thin wool sock covered by the other Wigwam sock. On my head I wore the Frogg Toggs hood and a Carhart cap/balaclava.
My sleeping rig is a JRB Bear Mountain Bridge hammock, JRB High Sierra Sniveller TQ (5*), Greylock 4 UQ (0*), and for good measure a Thermarest pad (R-3.4) in the sleeve of the hammock. Because it was windy and there were light flurries at the time I was setting up I also used the 2QZQ under quilt protector. All this was covered by a 10 x 10 Etowah tarp with custom panel pulls.
The experiment started at 7pm, 21 degrees. I set up camp and built a small fire. To ensure I had some overnight pee breaks, I had a few adult beverages. During the camp fire phase, the true value of the VB system became apparent. Normally at that temperature, and getting colder, I would have worn another layer. Usually a 200 or 300 weight fleece jacket I have or another down coat. With the VB system I didn’t need it. This means that on a backpacking trip I can leave that extra layer of bulk and weight at home and still be quite comfortable. I also noticed that I did not get a cold butt while hanging around the fire like I usually do. So far, I was impressed.
At last it was time to hit the hammock. By this time, it was down to 17 degrees. I took off the puffy but wore everything else. I also added a rather skimpy down hood that has proven effective for sleeping in the past. I settled in and went to sleep. By 1:30am I had two pee breaks and I was no colder doing it than any other night. When I got up in the morning to get ready for work it was 9 degrees, my new personal best, and other than my nose and left foot, everything was warm and dry. No frost, but the balaclava and opening of the down hood were rather soggy. The only things that got cold were the areas NOT covered by vapor barrier: My face (really my nose) and my left foot (which, as you may recall, was only in wool socks, not the waterproof VB sock).
BillyBob58, I hereby apologize for anything I may or may not have muttered about your intelligence and good sense regarding vapor barriers. Now I will be investing in some of those sexy Warmlite VB clothes.
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It got too cold for my outdoor thermometer so I got a reading from my indoor thermometer.
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