History
Vapor barrier insulation has been used in homes for over 80 years, and in
clothing since 1944. It took about 45 years for ignorance and stupidity to be
overcome in the building industry and get vapor barrier recognized as an
essential. The argument was that they needed porous walls to dry out water found
in them, ignoring the fact that it was the porosity that let water vapor in to
condense. Thus it is not too surprising to hear almost the same argument today
against vapor barrier in clothing! The other argument is actually optimistic:
they expect vapor barrier to always overheat you because high humidity
contributes to summer overheat! Wouldn't it be nice if we could just get all
needed warmth simply by controlling humidity! Unfortunately we can only get up
to 22 deg. added warmth from humidity retention with VB.
During the 1950s mountain hiking and backpacking became more popular. In rain
people wore their usual rain wear which worked well in other conditions, but
that strenuous activity caused them to overheat and get wet with sweat. Most
stopped the overheating by wearing less clothing under their rainwear. A few
thoughtless ones blamed their rainwear for their overheat, ignoring their
usually method to correct overheating by removing extra clothing. Knowing that
the coated rainwear was warmer than open weave fabric, they started a quest for
colder "breathable" rainwear.
During World War II, United States cold weather troops used vapor barrier
socks to totally cure frostbite and trenchfoot. Those led to the vapor barrier
Korean War "Bunny Boots," still the standard for military cold weather
use.
Stephenson Warmlite started promoting the use of vapor barrier socks
(baggies, bread bags, etc.) in 1957, the gloves, shirts, and sleeping bag
interiors in 1967. Choinard made quite durable VB socks from his tough "Sealcoat"
fabric. Black Diamond is now the brand name for this product.
Breathability
Most rainwear and sailing foul weather gear is made of coated nonporous
fabric. (Even Gore-Tex is only about 1/10 as breathable as uncoated fabric and
most people say Gore-Tex makes a rain jacket warm not cool.) Most people know
that raingear provides a lot of warmth if it is kept tightly sealed so wind
cannot blow through! Most ski parkas, storm overpants, and snowmobile suits have
a coating on the hidden inner surface of the outer fabric because coating works
so well for warmth and waterproofness. Sealed fabric is warmer because it will
not let cold air blow through to remove heat and it retains some humidity to
reduce the evaporative chilling of your skin. This tends to confuse some people:
your skin can feel dry and yet have high evaporative heat loss. Insensible sweat
glands keep your skin moist for flexibility, even when cold. We are falsely told
that "breathability" to make rainwear cold will also make your
clothing warm. But the slight porosity of "breathable" rainwear
doesn't prevent overheat when active, while highly porous clothes close a lot of
heat through convection and evaporation. The "B" myth is a typical but
dangerous mental reversal. It defies all logic and all known physics, yet
writers believe it just because they have seen it repeated so often in ads.
When cold air is warmed to skin temperature the relative humidity next to
your skin approaches zero. This causes rapid evaporative cooling of your skin.
When insensible sweating cannot keep up with the excessive drying your skin gets
dry and chapped. For example, when it is 32 degrees Fahrenheit outside,
evaporative cooling can more it feel 22 deg. colder. (At lower temperatures
there is only a small increase in evaporative heat loss since 32 deg. air is
almost as dry as any colder air -- cold air just cannot hold much humidity.)
Your body constantly produces, and loses heat. If heat loss matches production
you stay comfortable. If you are comfortable (clothed or unclothed) and then
increase heat production, you will overheat. Your body responds with sensible
sweating, to increase cooling by evaporation of sweat. If you lower the air
temperature or remove or vent clothing you soon cool, sensible sweating stops,
and your skin is soon dry. But even then, as long as the relative humidity in
the air next to your skin is less than 100 percent moisture in your skin will
continue to evaporate, cooling and drying your skin excessively. If humidity
next to you skin reaches 100 percent (meaning it cannot hold more water vapor),
evaporation stops, chilling stops, and insensible sweating stops. A humid summer
day feels much hotter than a day with the same temperature and low humidity.
Rain acts as a dehumidifier and that is what makes a rainy day feel much colder
than an equal temperature sunny, dry, but humid day.
If that was all there was to the problem, simply adding more clothes (and
using moisturizing skin creams) should take care of it, and that works fine for
short periods of cold exposure. But usually the outside relative humidity is 100
percent so the air cannot accept more humidity, and thus most of the moisture
evaporated from your skin condenses in the outer layers of your clothes. If you
sweat from overheat your skin gets wet and the sweat wicks into and soaks your
clothing without cooling you more because the air cannot accept more humidity.
That sweat only destroys the insulation of your outer clothes and chills you
later when you need warmth! Wicking may keep the sweat comfortably away from
your skin so you will not notice it, but that delays the intelligent action of
venting or removing excess clothing to stop the overheat. Then when you finally
slow down or stop, and you need your insulation, you find it is wet, and worse
than having no insulation. Before you die of hypothermia from believing those
false ads claiming their insulation is warm when wet, I suggest you soak you
jacket in a tub of water, shake it out and wear it to experience just how cold
it will really be!
Most of this is not a problem if your are just going outside for short
periods, or not changing activity levels greatly. But for someone jogging,
Nordic skiing, or hiking it can be a very serious, dangerous matter. Is there a
solution? Yes!
Warm when Wet?
What is warm when wet? A hot tub! But certainly not any porous insulation
used in clothing or sleeping bags. All porous bulk insulators, such as
polyester, Hollofil, Polarguard, Thinsulate, and even down are terribly cold
when wet. To stay warm you must keep those insulations dry. It will not make you
any warmer sitting in a freezing wet synthetic fill jacket, knowing it will only
take 6 hours instead of the 8 hours that a down jacket would take, because you
would have a severe case of hypothermia before then! The many insulations used
will all keep you warm if you take the simple precautions to use the excellent
rain gear now available and avoid soaking it with sweat, by wearing a vapor
barrier shirt with proper heat loss regulation. You may have noticed that down
is worn by water birds, while dry land birds, like chickens or turkeys, do not
wear down. But those water birds always keeps their down dry!
Foam insulation can keep you warm when wet. Open cell foams will not hold
much water, and will maintain full loft when wet, although evaporative heat loss
goes way up. Closed cell foam, such as used in wet suits, cannot absorb or pass
water, so insulation is unchanged when wet, and as in a "wet" suit,
you stay warm because you stay dry! (Note that in a wet suit that is not close
fitting enough to keep you mostly dry will not keep you warm!) Closed cell foams
will provide about twice the insulation per inch of thickness as porous
insulations (Thinsulate comes close to matching that), but unfortunately are
stiffer and heavier for the same insulation, and cannot be compressed for
packing.
Science
It has been reported that a person loses about four pounds of water through
sweat and respiration during a night of sleep in dry winter weather when using a
"breathable" sleeping bag. Weighing of porous sleeping bags in the
morning usually shows two to four pounds weight increase, confirming that
statement, and also showing that the sweat doesn't always make it out of the
bag. Instead, it condenses in the insulation leaving your bag wet. It takes 1080
BTU of heat from you to evaporate one pound of sweat. It also takes 140 BTU to
melt one pound of ice. Thus the heat to evaporate four pounds of sweat will melt
30.85 pounds of ice! (4 x 1080/140 = 30.85) Would you want to take 30.85 pounds
of ice to bed with you? That is the effect you get by not using vapor barrier
interior in your sleeping bag.
If you lose four pounds of sweat during eight hours of sleep you can expect
to lose much more during the sixteen hours you are awake and active. That is a
lot of dehydration and heat loss, and can lead to serious impairment of
circulation due to thickened blood, increasing risk of frostbite. You know that
warm humid conditions decrease evaporative losses and you can create that warm
humid condition around your body all day with vapor barrier clothing!
We normally tolerate overheating until we are bothered with wet skin from
sensible sweat. Then we ventilate or remove excess clothing or, if nude, seek
cooler location, a breeze, or cool water. If our clothing is absorptive it gets
very wet long before we notice the overheat, and then it may take a long time to
dry, which in winter can lead to hypothermia. If clothing is not absorptive
(vapor barrier) we notice sweat from overheat almost immediately, so can then
vent or remove excess insulation. Thus our insulating clothing remains dry and
ready to protect us when needed. The vapor barrier preserves the insulating
value of all our clothes as well as keeping us up to 22 degrees warmer when kept
snugly closed!
During short term changes in activity level at work in a protected
environment, it is nice to have clothing that soaks up sweat from overheat so we
can ignore it (until washday). For that reason, we do not like nonwicking
polyester or acrylic fiber against us, even though it is very
"breathable." A vapor barrier fabric with very wickable nylon inner
surface is much more comfortable since it rapidly distributes local sweat over a
large area so it is not annoying; you will notice and correct for overheat, but
wicking eliminates the wet feel. Thus modern wickable surface vapor barrier
materials such as Stephenson's Fuzzy Stuff are far more acceptable that the old
coated vapor barrier fabrics.
Heat, Humidity, Energy, Water
Water exists in three familiar states: solid (ice, snow, frost), liquid
(water, the wet state), and gas (humidity, steam, vapor). Although most people
are familiar with these forms, few are aware of the drastic differences between
them, especially the very large differences in energy states. This leads people
to mix up the relative characteristics, thus arriving at wrong, reversed
conclusions.
You are all probably aware of the large amount of heat energy it takes to
heat water, more than any other material (except hydrogen or helium). The basic
units of heat are based on the energy needed to increase water temperature one
degree. British Thermal Units (BTU) are commonly used in engineering, and I'll
stick to them to avoid confusion. One BTU is required to raise the temperature
of one pound of water one degree Fahrenheit. Water vapor takes about half a BTU,
and air about 1/4 BTU for one degree Fahrenheit temperature rise. To melt ice or
snow it takes 140 BTU/lb., or as much heat as it takes to heat one pound of air
583 degrees F! (A typical sleeping bag has 3/4 pound of air in the interior down
compartments. Raising that air from an outside 0 degree to 70 degrees takes 12.6
BTU, or the same heat it takes to melt 0.09 pound (1.44 oz) of ice or snow.
Evaporation of water at typical skin conditions requires 1080 BTU/lb., or 7.7
times as much heat as it takes to melt ice, and 4481 times the heat to raise air
temperature 1 deg./lb. From this you can see that humidity, or water vapor is
very energetic, hot stuff. It already has a lot of heat energy, so won't take
more from you. But liquid water has relatively low energy, so it can steal a lot
of heat from you if you let it escape.
Most sleeping bag manufacturers will tell you that in their porous interior
bags you will typically lose 4 pounds of water by evaporation every night. Think
of what that means in unnecessary heat loss: you would lose 4320 BTUs, or the
heat it would take to melt 30 pounds8 of ice, or the heat takes to make 87 cups
of coffee! And worse, that water then condenses just inside the outer layer of
the bag, decreasing the insulation, when you actually need more insulation to
make up for that high evaporative heat loss.
Heat and air conditioning engineers have known the above for many years. To
cool you they use dehumidifiers (condensers) so moisture can evaporate from your
skin. To warm you they use humidifiers and vapor barriers in walls to block
escape of humidity, so less evaporative cooling occurs on your skin. If you must
wear clothing for work protection or modesty in summer, you wear porous,
"breathable" clothes to promote the maximum evaporative cooling. Then
obviously when you wear clothes to keep you warm, you start with a vapor barrier
layer to prevent chilling evaporation. Yet somehow we are told repeatedly that
the same porous, "breathability" we use to chill us in summer is a
desirable and necessary feature of winter clothes and sleeping bags!
Benefits
1. Elimination of condensation in your tent. People who regularly
overdress and rely on wickable clothing to carry away sweat, add much more
humidity to a tent. If you have to change shirts due to sweat odors in less than
four days you will also likely cause excessive condensation in any tent you use.
Wearing vapor barrier clothing can help you to recognize and correct overheat.
2. Elimination of sweat odors on clothing and yourself. It is obvious
how outer clothing is protected. Apparently quick sensing and thus avoidance of
sweating, plus blocking of air circulation that causes sweat to turn rancid,
reduces or eliminates sweat odors on you and the vapor barrier clothing as well.
3. Prevent dehydration and thus reduces the amount of water you must
obtain and drink. Dehydration is a major contributor to frostbite, hypothermia
and altitude sickness. It thickens your blood, impairs circulation (thus
decreases proper heat and oxygen distribution), and reduces oxygen intake. It is
especially difficult to drink enough fluids when not wearing vapor barrier
clothes and all your water must come from melting snow! In several days the
weight of the fuel saved due to the use of vapor barrier can greatly exceed the
weight of vapor barrier clothing.
4. When you start with vapor barrier you can then wear any kind of
material for outer layers, no matter how uncomfortable or impractical it might
be otherwise since you will have no concern about getting it wet. Your outer
windbreak layer can be any coated or laminated fabric, preferably not
"breathable" so you do not have to be concerned with dirt causing it
to leak. When weight is an consideration, chose your intermediate layers solely
on the basis of most thickness per pound. Use the lightest urethane coated nylon
rainwear for the outer windbreaker, or wear ski parka and ski storm overpants
with urethane coated outer layer and polyester fiberfill insulation, which is
typically the lightest practical insulation per inch for clothing. Good goose
down is much lighter, but weight of extra fabric used normally more than offsets
the reduced insulation weight. Only in the very thick insulation needed for
sleeping bags is the great advantage of goose down really important.
How to Use
Shirts
Vapor barrier shirts are extremely efficient and are warmer than most people
would believe possible. Most people consider a vapor barrier shirt combined with
a Polar Plus jacket to be as warm as a down sweater! With this in mind, it is
apparent how easy it is to overdress when wearing vapor barriers. Thus, the
first thing to remember to use vapor barriers comfortably is to not overdress.
This is not as easy as it sounds since most people prefer to be overly warm
rather than comfortably cool. People will not object to overheating until sweat
is rolling off their skin.
Coated nylon against the skin gives a very clammy feeling. There are two
methods of getting around this problem. The first way is to wear a synthetic
long underwear top under the vapor barrier. The synthetic long underwear will
not absorb water. The second, better method is to purchase one of Stephenson's
wonderful "No-Sweat" shirts. These are made out of a urethane film
with a thin layer of nylon tricot bonded to the inside. The tricot disperses an
localized moisture and virtually prevents any clammy feeling.
Socks
Socks are where most people first experience vapor barriers in use. Most
everyone remembers their mothers wrapping their feet in bread bags before they
put on their boots to go out in the snow. That is almost all there is to it!
Remember to put on a thin pair of synthetic liner socks, then the bread bag and
then a pair of thicker socks (like rag wool).
Not convinced? Try this test! For those of you not convinced of vapor
barriers, try this approach. Use the above bread bag approach on one foot, and
just wear your standard sock on the other foot. Next go out and play in the cold
and see which foot is more comfortable!
In a Sleeping Bag
When you are awake and active it is easy to adjust insulation to avoid
overheat without venting vapor barrier clothing. When asleep, the normal
reaction to overheat is to push the covers away. With vapor barrier built into
the bag, pushing the top open to cool reduces the warmth of the vapor barrier
while still maintaining protection from condensation in the bag. (Sleeping bags
rarely get wet from the outside, but bags without vapor barrier interior almost
always get wet from the inside due to condensation and sweat!) If you wear vapor
barrier clothing in the bag the automatic response doesn't defeat the added
warmth, so temperature will be no better (or worse) than in non vapor barrier
bags, but you will protect the bag.
Vapor barrier in a sleeping bag causes no added warmth when vented, and
always protects the insulation from condensation and sweat soaking, thus it is
advisable to have vapor barrier in your bag for all seasons.
The most common excuse we hear from manufacturers and salespersons for not
selling vapor barrier lined bags and vapor barrier clothing is that they do not
want to take the time to explain it to their customers. Mighty inconsiderate, I
think!
High humidity greatly reduces evaporation of sweat and keeps you much warmer.
In summer you use a dehumidifier to lower humidity and cool you (at 86 deg. F.
100% relative humidity feels 30 degrees hotter than 10% relative humidity). In
winter, when air is dry you use a humidifier indoors for warmth (20 deg. F.
outside air with 100% relative humidity has only 9.2% relative humidity when
heated to 85 deg. F., typical skin temperature). Outdoors you can't use an
indoors humidifier, but can get the same effect if you block the escape of
humidity that escapes from you skin. You will notice an almost immediate
increase in warmth when VB clothing is put on and all openings closed tightly.
You will also notice immediate cooling when it is vented even slightly, since
water vapor (humidity) is a very energetic fast moving gas, and its escape
promotes the immediate evaporation of more sweat to replace it. Thus VB clothing
has the ability to provide a greater increment in warmth, with quicker
regulation of that increment than any other type of insulation (but it, like
radiate heat barriers has a single increment in warmth; you cannot double the
gain with double barriers!)
Conditions
We applaud Wil Steger for his North and South Pole dogsled trips. The North
Pole trip succeeded despite failure of the special Quallofill sleeping bags.
Within a few weeks the bags weighed 52 pounds, filled with ice, (condensed body
humidity due to no vapor barrier). To survive they squeezed three people, with
all their clothes and parkas on, into each pair of bags zipped together! Can you
imagine trying to backpack and survive with a 52 pound ice filled bag instead of
a nice dry compact down bag using a vapor barrier?
About the same time a Canadian-Soviet team skied across the pole (to and
from, no airlift out) using purchased Stephenson Warmlite sleeping bags which
stayed warm and dry for the whole trip. Steger bought Stephenson Fuzzy Stuff
vapor barrier liners for their sleeping bags for their much longer Antarctic
trip, and thus kept their bags warm and dry.
Wet Conditions (The Down Advantage)
Synthetics are promoted for wet conditions. That is okay since when it is
wet, it is warm, above freezing, suitable for heavy synthetics. The weight and
bulk penalty is not too bad for thin summer bags. If a bag gets wet (almost
always from inside due to the lack of a vapor barrier lining), synthetic bags
lose insulation much faster than down bags until added water is about three
times the insulation weight, then the synthetic bag is miserably cold and down
is still warm. Water fills up spaces between synthetics fibers and conducts away
heat, while down absorbs moisture within fibers and keeps insulating air spaces
open. Much more moisture is needed to collapse down, and that happens only if
the bag is carelessly dunked in water!
Down dries much faster, for a similar reason: interior moisture wicks to the
surface where it absorbs heat and evaporate rapidly. Synthetic fibers do not
wick water, thus all the heat needed to evaporate interior moisture is blocked
by insulation. Claims of quicker drying only refer to lightly surface damp
jackets or to washing when it is completely immersed, and is then based on
comparing drying of bags with all the down left in a big lump instead of being
distributed, thus is like comparing drying of one inch thick synthetic to ten
inch thick down.
If you foolishly wear a non waterproof parka in the rain with no rain
protection you may approach that immersed condition. In that dumb case lack of
wicking initially slows soaking of the synthetic, while down soaks faster and
may even collapse. If you are that silly then use a synthetic insulated parka,
not down. Since you do not walk in the rain in your sleeping bag, that has
nothing to do with insulation selection for your bag. Use synthetics (or low
loft down) for thin insulation where the extra weight and bulk is not a problem.
Use good down for thick insulation anytime weight and bulk must be reduced. In
either case always keep your insulation dry; that means using vapor barrier to
block the main water source, and proper rain wear and tent for protection.
Gore-Tex has been "improved" many times with increased glue
coverage and decreased porosity until humidity goes through about the same as
coated fabric. They learned that "breathability" is not important but
waterproofness is. Simple water repellents can be better. Spray-on fluorocarbon
or silicone repellents work well on tightly woven nylon, polyester, and cotton.
None are long lasting; like "breathable waterproofs," dirt and oils
can cause leaks. You need to spray it again every month, but it can make leaky
but tightly woven gear highly rain resistant. Repellents will not make wool or
other coarse fabrics rain tight, but will slow down water absorption somewhat.
Once wet though, wool is very slow drying and very cold to wear. If you wear
wool in wet conditions, be sure to wear good coated waterproof rainwear over it
and vapor barrier under it.
Polarguard, Hollofill, Quallofill, Kodafill, etc. all weigh about the same as
typical Chinese duck down. The advantages of down are greater compactability,
longer life, and faster drying (not that this should mean anything to you who
are careful and are not going to get your gear wet). Surprised? Go test it for
yourself! The wool industry is not the only one advertising their weakness as a
strength, although in this case, the synthetic fiber industry has been trying to
make a non-issue into the only thing they hope to be able to claim over down!
Compare two identical thickness jackets, with the same fabrics, one insulated
with polyester fiber, the other filled with down. Sprinkle each with water at a
slow rate (similar to rain wetting). Eventually the polyester collapses to about
1/3 original thickness and insulation almost disappears, while the insulation of
down barely changes. A while later the down collapses to almost nothing but
fabric thickness. Then lay them out to dry. Soon the polyester picks up a bit
more loft, but then seems to take forever to dry because the lofted surface
insulates the interior and blocks needed to evaporate water, and water will not
wick to the surface. Meanwhile the down seems to do nothing for awhile; as fast
as water evaporates from the surface, more interior water wicks to the surface.
Eventually, long before the polyester fully dries, the down dries and lofts to
original thickness. Some people have washed thick down bags, let all the down
lie in a big clump, and observed the clump taking several days to dry (like
drying a sixteen inch thick bag!). They have also gotten their thin polyester
insulated jacket wet in a rain storm, observed that the surface was totally wet
(and thus assumed that the jacket was saturated), and then noticed that it took
only a few hours to dry. By totally ignoring the differences in thickness' and
wetness they conclude that polyester dries faster than down!
Subject: Staying Warm & VB Clothing
Following the thread of cold weather clothing and staying warm, Paul Brown
and I have been conversing off-list about this topic. He was particularly
interested in vapor-barrier type clothing and my suggestion that he experiment
with different ideas before using them on a trip. At Paul's suggestion, I'll
share my $0.02 with the list. I've added some background info. [in brackets] to
help folks follow the conversation. This is by no means the definitive word on
vapor barrier clothing, keeping warm, etc. I'd certainly like to hear what
others have to say.
**** Extracted Text ****
I'm sure you've got a pretty good handle on winter camping, but my experience
comes from a number of years with backcountry skiing, ski mountaineering, snow
& ice climbing and other cold weather activities (my hands and feet are
still a little sensitive after a brush with frostbite).
I think what you're trying to achieve with plastic bags is the vapor barrier
effect. This is where a thin vapor-proof layer is placed near the skin and
insulative clothing is worn on top. The theory is that:
a) much water and heat is lost through evaporation, and
b) by reducing the evaporation you reduce the heat loss.
It works very very well in really cold situations. The key, in my experience
is to get the vapor barrier close to the skin. I've used a thin polyolefin or
polypropylene sock inside the vapor barrier and then wear heavy wool socks
outside. Be careful of wrinkles in the bag as this can cause blisters. I'd
experiment a few times when out for the day before banking on anything too much
for a winter camping trip, and always carry spare dry socks. Also, much of the
heat loss from your feet is through the sole of boots that are too light
(nothing different than your sleeping bag situation). Finally, be very careful
not to make to boots too tight, you need all the circulation you can get down
there when the mercury plunges.
BTW, I think a vapor barrier system also works very well for sleeping in
extremely cold weather. I've tested various clothing options when shoveling
snow, walking the dog, sledding with the kids, or otherwise close to home in a
cold setting. Day trips are also good time to try something new. This enables me
to fine-tune the layering without risking myself on a backcountry trip with
unfamiliar gear. Your proposed approach sounds okay to me [....as an experiment
I might try a latex glove on one hand under my mittens and a plastic bag on one
foot under my sox and see if I notice a difference...]. I've not used latex
gloves myself, so can't really tell you from direct experience. The use of thin
liner socks helps to avoid the feeling that your feet are swimming in sweat.
I think my vapor barrier socks came from Campmor or maybe REI. They're very
thin neoprene rubber with a fairly comfortable fleece lining. They fit snugly so
I don't have to worry about blisters. Again, I caution against trying to cram
extra socks (even VB type) into boots that are too tight. My winter boots have a
felt liner (I always carry spares so they can be changed out when wet). Ski
boots, etc. are sized to fit over the appropriate socks. My cold weather
clothing system consists of synthetic long underwear (weight varies w/ expected
activity level, temps, etc.), fleece or pile mid layers (vest, jacket, and
pants, all w/ vent zippers), and Gore-Tex top layer (wind/water protection).
I've moved to the synthetics because of their performance to weight ratio. They
also dry quicker (NOT NEAR THE FIRE!) and keep you warm even if wet. Rather than
VB gloves, I usually wear thin thermax or polypro gloves, then either wool or
fleece mittens, and some sort of outer shell mitten (Gore-Tex or similar). This
gives flexibility in the layering and dexterity as required (try working a
camera or surveying instrument with big mitts on). I recognize that this type of
outfit is pricey, but I think you can assemble a similar outfit without spending
a fortune. It's really a matter of what your needs and budget are.
The sleeping bag liner is thin coated nylon. It's made by North Face and fits
inside my mummy bag (700 fill goose down with a Gore-Tex outer layer). The
theory here is to protect the down insulation from vapor on both the inside and
outside and to allow any moisture that does get in to evaporate through the
Gore-Tex (driven by the temp. differential). Needless to say, this arrangement
is not on the cheap, nor is it appropriate for everyone (probably overkill for
most folks, but vital in a snow cave or high-altitude bivouac). It is really
warm and about as lightweight as I could make it for the temps encountered. I
wear thermax long undies and a good thermax hat to sleep in. If it's really cold
I'll include the fleece pants and vest, but the danger is that they become too
wet to wear the next day. I take the gloves in with me too, but most other
clothing will go under the bag. I use both a ThermaRest and a thin closed cell
pad beneath my bag if its really cold (also more comfortable on tired bones). We
also keep smaller pieces of closed cell foam to sit on, put the stove on, etc.
To tell the truth, I also have a synthetic fill bag which gets a good bit of
use, because the system described above is too warm for some trips (even in
"winter"). I've tried a number of different systems and found the VB
liner best in really cold weather (single digits and below), and a good
synthetic fill bag better in moderately cold temps. I don't really have a good
explanation for this, but I suspect it's because I end up feeling too
"clammy" in the VB liner when it's warmer. No good idea why.
I tend to agree with much of what was posted about staying warm (especially
NOT sending a kid back to bed without determining the situation and getting him
stabilized first), taking a leak just before bed, and having water/snack readily
available. I often store water bottles inside my bag (double zip locked), because
when you've got to melt snow and fuel is scarce, you don't want to waste any. I
use white gas exclusively during backcountry trips, especially in cold weather,
and only have a propane stove for "car camping." I think one of the
biggest dangers with sending the kid back to bed is turning him off from winter
trips all together. As a young scout I spent some very cold miserable nights
feeling sorry for myself before getting it together with the help of a great ASM.
He showed interest in me, and that made a big difference in my entire scouting
experience.
Please Read The Website
Disclaimer!
Copyright 1986-2012, The Survival & Self-Reliance Studies Institute (SSRsi), All
Rights Reserved
Site conceptualized, designed, created & maintained by MEG Raven
Snail Mail: SSRsi, PO Box 2572 Dillon, CO. 80435-2572