[at-l] Re: Tablecloth VBL

[jmayer@rochester.rr.com (Jim Mayer)]

>From what I've read (which jives with my own, limited, experience) VB gear
tends to get used in two different ways:

(1) VB socks are almost standard winter mountaineering gear.  They work
because they keep your heavy socks and boot insulation dry.  You do sweat,
your feet can get damp (though I haven't had too much of a problem), but it
beats the heck out of frostbite.  Most people wear a pair of thin liner
socks inside the VB sock, and a regular wool or synthetic heavy sock over
the VB sock.  It is important to let your feet dry out well at night.

(2) VB sleeping bag liners, VB shirts, and VB pants are a different story.
The idea here is to stop "insensible" perspiration.  Basically, your body is
constantly trying to maintain a slightly most "microclimate" around itself.
As a result, in a dry environment your skin contantly gives off some
moisture.  You're not aware of this, so it is called "insensible" sweat.
This is all fine and well, but in cold conditions your body still has to pay
the energy cost of evaporating liquid water, so you lose heat this way.  For
most (but possibly not all) people this sweating shuts down once the
humidity reaches an appropriate level.... this is why VB shirts, pants, and
sleeping bag liners work.  They trap the moisture, raise the humidity, and
your body stops emitting as much moisture so thing stay relatively dry.

Great!  But there's a catch... if you wrap yourself up and get all toasty,
you'll start sweating because you're hot... and then the VB clothing will
get wet.  So the secret of using VB gear is to keep yourself comfortable,
but just a touch on the cool side.

Another plus, by the way, is that you don't have to drink all the water you
don't sweat, so it is easier to stay hydrated.  Staying well hydrated is an
important part of staying warm in the winter.

Anyway, VB gear (except for socks and gloves) seems to be mostly used in
camp or at night... or at least not during aerobic activities.  When you're
working up a sweat you are... well... sweating and it is hard to keep the VB
clothing from getting soaked.

By the way, Stephenson VB clothes have a fuzzy finish on the inside that
helps wick any sweat around.  This makes it quite comfortable next to the
skin.  Most other VB gear has a slick finish and should be worn over long
underwear.

Hope this helps.

-- Jim
----- Original Message -----
From: "cosmo catalano, jr." <Cosmo.A.Catalano@williams.edu>
To: <at-l@mailman.backcountry.net>
Sent: Thursday, January 04, 2001 5:26 PM
Subject: [at-l] Re: Tablecloth VBL


> Excuse my ignorance, but doesn't wrapping yourself in plastic make
> things kind of slimy in there?  The thought of sleeping in a plastic
> bag makes me want to take a shower.  I have very little outdoor
> winter overnight experience, so maybe when it's that cold and dry you
> just don't put our much water vapor?
>
> Cosmo the sweaty
>
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