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Re: [Hammock Camping] Frost free?

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  • m2b1997
    I agree Ed, that the moisture freezing around the mouth is to be expected, hence why I wasn t concerned by it or even thinking anything about. I was surprised
    Message 1 of 13 , Jan 6, 2009
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      I agree Ed, that the moisture freezing around the mouth is to be
      expected, hence why I wasn't concerned by it or even thinking
      anything about. I was surprised by it for a second or so, night one
      or two, until I realized I should be seeing it.

      The sleeping bag seemed dry, just cold, as could be expected given 14
      degrees. It was the hammock though that had the frost on it, other
      than around the mouth. That's why I'm a bit perplexed. I hadn't
      thought about the body heat being lost but that does make perfectly
      good sense.

      Around the face the frost was the worst...but I still had it, ONLY on
      the hammock, all the way down at the feet. The weather was cloudy
      turned clear by morning, no precip overnight. In the several times I
      woke up overnight it was anywhere from partly cloudy to clear. I'm
      not sure what the dew point was. I'm going to have to pay a little
      more attention the next time and see if I notice that being the true
      culprit as it doesn't seem like the breath should be able to make it
      all the way down to the feet.

      Just one strange/stupid curiousity that has come up in my mind. In
      the case of winter camping would you be better off with a cotton
      versus a nylon hammock? Yes, this seems like a real dumb question,
      but think about it for a moment. During the summer months, nylon
      only, I wouldn't consider anything else otherwise, simple because of
      the rain. Winter months though, when you find yourself in a
      situation like I did last night the cotton hammock would have the
      tendency to absorb the moisture instead of the sleeping bag. This
      would keep the sleeping bag drier. There's nothing 'waterproof'
      around you to keep the moisture in so it collects on the sleeping
      bag. Am I wrong on this thinking? Is that why the hammock had the
      frost at the feet but the sleeping bag was dry? The thought just
      came to me as I was typing this.

      MEANT 2B
      GAME '97
    • Ed Speer
      Cotton vs. nylon hammock might make a minor difference on the amount of moisture collecting on the outer side of the fabric, but not much. But you re right
      Message 2 of 13 , Jan 6, 2009
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        Cotton vs. nylon hammock might make a minor difference on the amount of
        moisture collecting on the outer side of the fabric, but not much. But
        you're right that a cotton hammock around a nylon sleeping bag might tend to
        absorb more of the body moisture that condenses on the outside fabrics. I
        guess you might end up with a wet hammock & a drier sleeping bag. But since
        they're still in contact with each other, they're both be wet. I find that
        a small chamois cloth is ideal for wiping off the condensed moisture that
        tends to bead up on nylon fabrics-especially those with durable water
        resistance (DWR) treatments. I use it in the am before taking down the
        hammock.



        But remember that your body moisture will be driven to the outermost fabric,
        no matter if it is cotton or nylon. In most camping temperatures, as long
        as the fabrics are breathable, your body heat will drive the body moisture
        to the outermost fabric. I suspect both your sleeping bag & hammock had
        moisture (frost) on them where they were directly contacting the outside
        air-where the hammock fabric directly covered the sleeping bag fabric, only
        the hammock fabric should have had frost. It's usually the outermost fabric
        that collects the moisture-it's the fabric directly in contact with the cold
        air that collects the condensation. The warmth from your body is enough to
        drive your body moisture all the way thru multiple layers of breathable
        fabrics; except in extreme cold conditions. Only when your escaping body
        moisture meets a vapor barrier or a cold interface like the freezing outside
        air, will it stop & condense. In extreme cold situations, that cold
        interface could occur inside your insulation! Members of arctic expeditions
        sometimes find that their very, very thick sleeping bags keep getting
        heavier and heavier each night-it's because their escaping body moisture
        meets the cold interface & freezes before it reaches the outside of the
        insulation; they end up with ice accumulating inside the insulation & no way
        to get it out!



        Your reply suggests one of my favorite tricks for cold weather
        camping-wicking long johns. This fabric moves my body moisture to the outer
        side of the fabric leaving the inner side of the fabric (the side against my
        skin) dry. I'll even use wicking long johns inside a vapor barrier bag to
        keep wetness away from my skin..Ed



        Moderator, Hammock Camping List

        Author, Hammock Camping book

        Editor, Hammock Camping Newsletters

        Owner, Speer Hammocks Inc



        From: hammockcamping@yahoogroups.com [mailto:hammockcamping@yahoogroups.com]
        On Behalf Of m2b1997
        Sent: Tuesday, January 06, 2009 11:44 AM
        To: hammockcamping@yahoogroups.com
        Subject: Re: [Hammock Camping] Frost free?



        I agree Ed, that the moisture freezing around the mouth is to be
        expected, hence why I wasn't concerned by it or even thinking
        anything about. I was surprised by it for a second or so, night one
        or two, until I realized I should be seeing it.

        The sleeping bag seemed dry, just cold, as could be expected given 14
        degrees. It was the hammock though that had the frost on it, other
        than around the mouth. That's why I'm a bit perplexed. I hadn't
        thought about the body heat being lost but that does make perfectly
        good sense.

        Around the face the frost was the worst...but I still had it, ONLY on
        the hammock, all the way down at the feet. The weather was cloudy
        turned clear by morning, no precip overnight. In the several times I
        woke up overnight it was anywhere from partly cloudy to clear. I'm
        not sure what the dew point was. I'm going to have to pay a little
        more attention the next time and see if I notice that being the true
        culprit as it doesn't seem like the breath should be able to make it
        all the way down to the feet.

        Just one strange/stupid curiousity that has come up in my mind. In
        the case of winter camping would you be better off with a cotton
        versus a nylon hammock? Yes, this seems like a real dumb question,
        but think about it for a moment. During the summer months, nylon
        only, I wouldn't consider anything else otherwise, simple because of
        the rain. Winter months though, when you find yourself in a
        situation like I did last night the cotton hammock would have the
        tendency to absorb the moisture instead of the sleeping bag. This
        would keep the sleeping bag drier. There's nothing 'waterproof'
        around you to keep the moisture in so it collects on the sleeping
        bag. Am I wrong on this thinking? Is that why the hammock had the
        frost at the feet but the sleeping bag was dry? The thought just
        came to me as I was typing this.

        MEANT 2B
        GAME '97





        [Non-text portions of this message have been removed]
      • m2b1997
        Are sweat suits designed just like long johns. I never thought they was meant to wick the moisture just to keep the heat in? The idea for the vapor barrier as
        Message 3 of 13 , Jan 6, 2009
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          Are sweat suits designed just like long johns. I never thought they
          was meant to wick the moisture just to keep the heat in?

          The idea for the vapor barrier as I see it right now would be to wear
          nothing but keep your clothes between the vapor barrier and the
          sleeping bag, make sure to include a towel. Granted I haven't read
          up on the idea any but this is what makes the most sense right now.
          Your clothes would stay dry and you would stay warm. Just make sure
          you can change clothes in a flash. Sorry about the pun, couldn't
          resist.

          Definitely would have to have it set up as a vapor bag so when you
          went to get out the moisture would stay in the bag. Yeah, just
          thinking.

          Like I said I did 14 degrees last night and it wasn't that bad. Much
          better than 10 degrees on the ground a week or so ago. MUCH BETTER.
          Strangely it seems like it is warmer to stay off the ground than to
          stay on the ground. I've heard you and others talk about how you can
          get so much colder by sleeping in a hammock. I seem thus far to find
          the exact opposite scenario. I guess I need to push the limits to
          change things around.

          MEANT 2B
        • Dave Womble
          ... Ed... seems like this comes up every year about this time, and for good reason. I think you, I, and a lot of winter campers use some type of material to
          Message 4 of 13 , Jan 7, 2009
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            --- In hammockcamping@yahoogroups.com, "Ed Speer" <ed@...> wrote:
            >... I'd love to see vapor barriers discussed on this List for I know
            > many of you have tried them with varying results. ...

            Ed... seems like this comes up every year about this time, and for
            good reason. I think you, I, and a lot of winter campers use some
            type of material to breathe through in cold weather. I use a bandanna
            or some type of fleece to breathe through in cold weather to keep from
            getting a sore throat and to limit how much moisture I lose due to
            exhaling. That cuts down on the frost or moisture also.

            I know Ed had things to say about vapor barriers in his book on
            hammock camping. Over the years I have tried to keep an updated
            document on my thoughts about vapor barriers and it is probably a good
            time to re-post that. Here it is:

            My Thoughts on Vapor Barriers... again.

            Vapor barriers aren't that easy to use if you don't understand what is
            going on and they aren't that hard to use if you do. Does that make
            any sense? If it does, you don't need to read any further. If it
            doesn't, then read on and see if this helps.

            I use plastic or silnylon as a vapor barrier between my hammock and my
            SnugFit Underquilt. The suspension system on the SnugFit helps keep
            the vapor barrier against the fabric of the hammock to minimize air
            gaps that would encourage insensible perspiration to condense and
            pool. With the vapor barrier held in place against the underside of
            the hammock fabric, the hammock fabric wicks away any slight buildup
            of insensible perspiration where it can more easily evaporate and I
            usually don't even notice it. I pick when I do that and understand how
            to use it. It is been very effective for me at extending the lower
            temperature range that I can use my underquilt. I would not use a
            vapor barrier when I was using the underquilt in warmer conditions
            because then I would be dealing with sweat and there would be larger
            amounts of sweat/moisture to deal with as the vapor barrier would
            cause me to overheat even more and prevent moisture from sweat from
            passing through the breathable underquilt.

            In general, breathable insulation works best when your insulation is
            getting too warm for you and less breathable insulation works best
            when your insulation is not quite warm enough for you. That has
            everything to do with how, when, and why your body produces sweat (or
            sensible perspiration) and insensible perspiration.

            Your body produces sweat to help cool off at the outer surface of your
            skin with evaporative cooling when you overheat. Your body does not
            produce sweat when you are not overheating... you don't just leak
            water through your skin all the time. When you are not sweating, your
            body can produce insensible perspiration to keep your skin from drying
            out. If your skin is moist enough, or not too dry, your body doesn't
            produce insensible perspiration because it senses that it doesn't need to.

            It takes energy for your body to produce insensible perspiration. When
            you are not overheating and your skin is not producing sweat, a vapor
            barrier will cause your skin to quit producing insensible perspiration
            after some period of time. Your skin quits producing insensible
            perspiration because the vapor barrier creates a high humidity
            environment by trapping the moisture from your previous insensible
            perspiration. When this happens your body does not use energy to
            produce that insensible perspiration anymore and can use that energy
            to help keep you warmer. It a sense, your body becomes a more
            efficient furnace.

            A vapor barrier is not so good when used at the wrong time or when
            used incorrectly. When you are overheating and using a vapor barrier,
            your skin continually produces sweat as a means of cooling off via
            evaporative cooling. The vapor barrier prevents the evaporative
            cooling because the sweat is trapped by the vapor barrier. You just
            keep sweating and moisture can build up. You need to do something to
            keep from overheating because what your body is doing isn't working
            because of the vapor barrier. You need to remove the vapor barrier,
            vent, or remove insulation.

            When you use a vapor barrier with breathable insulation between it and
            your skin, that breathable insulation is subject to getting moist or
            even wet from insensible perspiration. The insensible perspiration
            will initially pass through the breathable insulation and stop when it
            hits the vapor barrier. This continues until the humidity builds up
            enough for skin to quit producing insensible perspiration. But until
            that happens that breathable insulation is going to be getting moist
            too. What you want is a thin wickable sheet of fabric between you and
            the vapor barrier such that it can wick any slight moisture buildup
            away where it can evaporate into the surrounding air. Of course it
            helps for the surrounding air to be able to absorb that moisture
            because if it can't, it won't and you will be clammy.

            And of course, if you use breathable insulation between you and a
            vapor barrier while you are overheating, you will soak that breathable
            insulation with sweat (sensible perspiration). That is bad and that
            happens when people don't understand how and when to use a vapor barrier.

            When closed cell foam pads are used with breathable underquilts in
            hammocks, we get a situation where the overall insulation is greater
            than the sum of the various components making up the insulation. That
            is because closed cell foam pads are also vapor barriers. The vapor
            barrier stops your body from producing insensible perspiration and
            causes the breathable underquilt to provide more apparent insulation
            (although it isn't doing anything different) because your body is now
            operating more efficiently at keeping you warm. If you use a ccf pad
            that provides 20F worth of insulation with a breathable underquilt
            that provides 40F worth of insulation by itself, you will end up with
            more than 20 + 40 = 60F worth of insulation. You might end up with
            70F worth of insulation or more.

            You can also wear a vapor barrier to help stay warmer. You can do it
            selectively for parts of your body or you can do it for your whole
            body (but don't forget you need to breathe). You can use vapor
            barrier liners for sleeping bags or plastic bags over your feet, head
            (as a hat), torso, etc or rain suits. I haven't tried a vapor barrier
            liner for a sleeping bag but have used a rain suit for a vapor barrier
            (even breathable ones work) and used plastic bags over feet, head, and
            torso with success. I always have used thin liner material under them
            with the understanding they would likely get slightly moist from
            insensible perspiration.

            Vapor barriers work well for people that know when and how to use them
            and are often problems or even disasters for people that don't.

            [I am a little conflicted about this particular paragraph. On one
            hand I feel it is important if this write up is going to be used as
            somewhat of a reference for vapor barriers. On the other hand I don't
            want to scare folks about a problem they aren't likely to encounterÂ…
            but here goes.] Understanding vapor barriers, how to use them, when
            to use them, and when not to use them becomes more important the
            colder it gets. I don't have experience in extremely cold
            temperatures but my understanding is that if you use breathable
            insulation at extremely cold temperatures you risk insensible
            perspiration condensing inside the insulation as the dew point
            temperature moves inside the bag itself. Vapor condensing inside the
            bag creates moisture inside the bag and is just as troubling as sweat
            or any other moisture getting inside the bag. When this happens the
            insulation may not dry out at the temperatures you find yourself in
            and can accumulate over the days you are exposed to extremely cold
            temperatures. This can be a troubling phenomenon if it occurs as your
            bag can become increasingly heavier and less efficient. For most of
            us this isn't an issue as I am referring to extremely cold conditions
            and we shouldn't be concerned about the dew point moving inside the
            bag itself at the more moderate cold conditions that most of us camp
            or backpack in. I only mention it because it should be of interest to
            the few individuals that are camping or backpacking in extremely cold
            temperatures.

            Dave Womble
            aka Youngblood AT2000
            designer of the Speer Segmented Pad Extender, SnugFit Underquilt, and
            WinterTarp
            May 13, 2008
            Revised December 1, 2008
          • Hollis Easter
            Dave, I ve been reading stuff about winter mountaineering for a few years now, and your explanation of the theory and practice behind vapor barriers is
            Message 5 of 13 , Jan 7, 2009
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              Dave,

              I've been reading stuff about winter mountaineering for a few years now,
              and your explanation of the theory and practice behind vapor barriers is
              probably the most cogent I've read. It matches my own experience with
              them, too.

              Something I might add about vapor barriers is that they're somewhat
              different from other forms of gear in that you need some acquired
              learning before it'll work well for you. The first few times you use a
              VB system, chances are good that you'll get something wrong, whether
              large or small. Maybe you've got too much insulation, so you start
              sweating. Maybe you forget about the VB liner on your sleeping bag, and
              you bring your wet gloves and hat inside it with you, and they're
              sponges in the morning. Maybe... you get the idea.

              The point being that it's never a great idea to bring new forms of gear
              out into the field without practicing at home, but it's an especially
              poor choice if you're just learning to use VB. Sleep out in the backyard
              for a few nights first, where it doesn't matter if you soak your
              insulation or get cold or whatever.

              There's a neat trick I stumbled onto accidentally while testing my
              Hennessy SuperShelter--it'll prove the worth of VB to you. I was
              sleeping out in 20 F weather, with wind. I had the space blanket in VB
              position (pressed up against the hammock body, with insulation OUTSIDE
              it). I didn't quite snug the space blanket up properly the first time,
              though, and there was a spot on my shoulders that didn't have VB.

              I slept really comfortably, and didn't notice any problems (including on
              my shoulders). However, when it came time to pack up, it was easy to
              tell where I'd missed the VB: the open-cell foam was wet enough that I
              could wring some water out of it. It really illustrated the point.

              You could try that on your own by wearing rain pants to bed and then
              looking at the difference in condensation between your legs and torso on
              the inside of the sleeping bag... or you could tape a trash bag to half
              the underside of your hammock. There are lots of ways to mess with it.

              VB is a really useful trick that, like ultralight gear, requires
              knowledge to make it go. I loved your article; have you considered
              sticking it in the files section of the Yahoo group?

              Best,
              Hollis
              On Wed, Jan 07, 2009 at 12:40:36PM -0000, Dave Womble wrote:
              > --- In hammockcamping@yahoogroups.com, "Ed Speer" <ed@...> wrote:
              > >... I'd love to see vapor barriers discussed on this List for I know
              > > many of you have tried them with varying results. ...
              >
              > Ed... seems like this comes up every year about this time, and for
              > good reason. I think you, I, and a lot of winter campers use some
              > type of material to breathe through in cold weather. I use a bandanna
              > or some type of fleece to breathe through in cold weather to keep from
              > getting a sore throat and to limit how much moisture I lose due to
              > exhaling. That cuts down on the frost or moisture also.
              >
              > I know Ed had things to say about vapor barriers in his book on
              > hammock camping. Over the years I have tried to keep an updated
              > document on my thoughts about vapor barriers and it is probably a good
              > time to re-post that. Here it is:
              >
              > My Thoughts on Vapor Barriers... again.
              >
              > Vapor barriers aren't that easy to use if you don't understand what is
              > going on and they aren't that hard to use if you do. Does that make
              > any sense? If it does, you don't need to read any further. If it
              > doesn't, then read on and see if this helps.
              >
              > I use plastic or silnylon as a vapor barrier between my hammock and my
              > SnugFit Underquilt. The suspension system on the SnugFit helps keep
              > the vapor barrier against the fabric of the hammock to minimize air
              > gaps that would encourage insensible perspiration to condense and
              > pool. With the vapor barrier held in place against the underside of
              > the hammock fabric, the hammock fabric wicks away any slight buildup
              > of insensible perspiration where it can more easily evaporate and I
              > usually don't even notice it. I pick when I do that and understand how
              > to use it. It is been very effective for me at extending the lower
              > temperature range that I can use my underquilt. I would not use a
              > vapor barrier when I was using the underquilt in warmer conditions
              > because then I would be dealing with sweat and there would be larger
              > amounts of sweat/moisture to deal with as the vapor barrier would
              > cause me to overheat even more and prevent moisture from sweat from
              > passing through the breathable underquilt.
              >
              > In general, breathable insulation works best when your insulation is
              > getting too warm for you and less breathable insulation works best
              > when your insulation is not quite warm enough for you. That has
              > everything to do with how, when, and why your body produces sweat (or
              > sensible perspiration) and insensible perspiration.
              >
              > Your body produces sweat to help cool off at the outer surface of your
              > skin with evaporative cooling when you overheat. Your body does not
              > produce sweat when you are not overheating... you don't just leak
              > water through your skin all the time. When you are not sweating, your
              > body can produce insensible perspiration to keep your skin from drying
              > out. If your skin is moist enough, or not too dry, your body doesn't
              > produce insensible perspiration because it senses that it doesn't need to.
              >
              > It takes energy for your body to produce insensible perspiration. When
              > you are not overheating and your skin is not producing sweat, a vapor
              > barrier will cause your skin to quit producing insensible perspiration
              > after some period of time. Your skin quits producing insensible
              > perspiration because the vapor barrier creates a high humidity
              > environment by trapping the moisture from your previous insensible
              > perspiration. When this happens your body does not use energy to
              > produce that insensible perspiration anymore and can use that energy
              > to help keep you warmer. It a sense, your body becomes a more
              > efficient furnace.
              >
              > A vapor barrier is not so good when used at the wrong time or when
              > used incorrectly. When you are overheating and using a vapor barrier,
              > your skin continually produces sweat as a means of cooling off via
              > evaporative cooling. The vapor barrier prevents the evaporative
              > cooling because the sweat is trapped by the vapor barrier. You just
              > keep sweating and moisture can build up. You need to do something to
              > keep from overheating because what your body is doing isn't working
              > because of the vapor barrier. You need to remove the vapor barrier,
              > vent, or remove insulation.
              >
              > When you use a vapor barrier with breathable insulation between it and
              > your skin, that breathable insulation is subject to getting moist or
              > even wet from insensible perspiration. The insensible perspiration
              > will initially pass through the breathable insulation and stop when it
              > hits the vapor barrier. This continues until the humidity builds up
              > enough for skin to quit producing insensible perspiration. But until
              > that happens that breathable insulation is going to be getting moist
              > too. What you want is a thin wickable sheet of fabric between you and
              > the vapor barrier such that it can wick any slight moisture buildup
              > away where it can evaporate into the surrounding air. Of course it
              > helps for the surrounding air to be able to absorb that moisture
              > because if it can't, it won't and you will be clammy.
              >
              > And of course, if you use breathable insulation between you and a
              > vapor barrier while you are overheating, you will soak that breathable
              > insulation with sweat (sensible perspiration). That is bad and that
              > happens when people don't understand how and when to use a vapor barrier.
              >
              > When closed cell foam pads are used with breathable underquilts in
              > hammocks, we get a situation where the overall insulation is greater
              > than the sum of the various components making up the insulation. That
              > is because closed cell foam pads are also vapor barriers. The vapor
              > barrier stops your body from producing insensible perspiration and
              > causes the breathable underquilt to provide more apparent insulation
              > (although it isn't doing anything different) because your body is now
              > operating more efficiently at keeping you warm. If you use a ccf pad
              > that provides 20F worth of insulation with a breathable underquilt
              > that provides 40F worth of insulation by itself, you will end up with
              > more than 20 + 40 = 60F worth of insulation. You might end up with
              > 70F worth of insulation or more.
              >
              > You can also wear a vapor barrier to help stay warmer. You can do it
              > selectively for parts of your body or you can do it for your whole
              > body (but don't forget you need to breathe). You can use vapor
              > barrier liners for sleeping bags or plastic bags over your feet, head
              > (as a hat), torso, etc or rain suits. I haven't tried a vapor barrier
              > liner for a sleeping bag but have used a rain suit for a vapor barrier
              > (even breathable ones work) and used plastic bags over feet, head, and
              > torso with success. I always have used thin liner material under them
              > with the understanding they would likely get slightly moist from
              > insensible perspiration.
              >
              > Vapor barriers work well for people that know when and how to use them
              > and are often problems or even disasters for people that don't.
              >
              > [I am a little conflicted about this particular paragraph. On one
              > hand I feel it is important if this write up is going to be used as
              > somewhat of a reference for vapor barriers. On the other hand I don't
              > want to scare folks about a problem they aren't likely to encounter*
              > but here goes.] Understanding vapor barriers, how to use them, when
              > to use them, and when not to use them becomes more important the
              > colder it gets. I don't have experience in extremely cold
              > temperatures but my understanding is that if you use breathable
              > insulation at extremely cold temperatures you risk insensible
              > perspiration condensing inside the insulation as the dew point
              > temperature moves inside the bag itself. Vapor condensing inside the
              > bag creates moisture inside the bag and is just as troubling as sweat
              > or any other moisture getting inside the bag. When this happens the
              > insulation may not dry out at the temperatures you find yourself in
              > and can accumulate over the days you are exposed to extremely cold
              > temperatures. This can be a troubling phenomenon if it occurs as your
              > bag can become increasingly heavier and less efficient. For most of
              > us this isn't an issue as I am referring to extremely cold conditions
              > and we shouldn't be concerned about the dew point moving inside the
              > bag itself at the more moderate cold conditions that most of us camp
              > or backpack in. I only mention it because it should be of interest to
              > the few individuals that are camping or backpacking in extremely cold
              > temperatures.
              >
              > Dave Womble
              > aka Youngblood AT2000
              > designer of the Speer Segmented Pad Extender, SnugFit Underquilt, and
              > WinterTarp
              > May 13, 2008
              > Revised December 1, 2008
              >
              >
            • Ed Speer
              Thanks Dave, your input is most valuable. You & I have discussed vapor barriers many times & I know your understanding comes from experience plus your
              Message 6 of 13 , Jan 7, 2009
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                Thanks Dave, your input is most valuable. You & I have discussed vapor
                barriers many times & I know your understanding comes from experience plus
                your analytical mind! Some descriptions of vapor barriers by other people &
                posted on various sites are confusing or even outright wrong. Thanks for
                taking the time to write down your thoughts & for sharing them with us.



                I often say that all outdoor fabrics used for camping exhibit some form of
                vapor barrier-some fabrics are just better than others. Even no-see-um bug
                netting is a vapor barrier-just not a very good one. Bug netting does hold
                in some of your body heat & blocks a bit of cold wind as seen on subfreezing
                nights. I've even had snow inside my hammock when the bug net trapped some
                of my expelled breath & allowed the moisture to condense, freeze & fall back
                on my face as snow. In warmer temps, the bug net can trap enough body heat
                & moisture to make me uncomfortably warm & clammy. So we all deal with
                vapor barrier fabrics each time we camp. Dave's observation is correct that
                we'll be more comfortable when we understand how vapor barriers work & how
                to add, remove, or vent them when needed as conditions dictate. Sometimes
                outside temperature & humidity changes during a single night might require
                the camper to make appropriate changes to maintain comfort. While I wish it
                was otherwise, no one fabric or vapor barrier is magically perfect for all
                conditions-so its camper be ware..Ed



                Moderator, Hammock Camping List

                Author, Hammock Camping book

                Editor, Hammock Camping Newsletters

                Owner, Speer Hammocks Inc



                From: hammockcamping@yahoogroups.com [mailto:hammockcamping@yahoogroups.com]
                On Behalf Of Dave Womble
                Sent: Wednesday, January 07, 2009 7:41 AM
                To: hammockcamping@yahoogroups.com
                Subject: Re: [Hammock Camping] Frost free?



                --- In hammockcamping@yahoogroups.com
                <mailto:hammockcamping%40yahoogroups.com> , "Ed Speer" <ed@...> wrote:
                >... I'd love to see vapor barriers discussed on this List for I know
                > many of you have tried them with varying results. ...

                Ed... seems like this comes up every year about this time, and for
                good reason. I think you, I, and a lot of winter campers use some
                type of material to breathe through in cold weather. I use a bandanna
                or some type of fleece to breathe through in cold weather to keep from
                getting a sore throat and to limit how much moisture I lose due to
                exhaling. That cuts down on the frost or moisture also.

                I know Ed had things to say about vapor barriers in his book on
                hammock camping. Over the years I have tried to keep an updated
                document on my thoughts about vapor barriers and it is probably a good
                time to re-post that. Here it is:

                My Thoughts on Vapor Barriers... again.

                Vapor barriers aren't that easy to use if you don't understand what is
                going on and they aren't that hard to use if you do. Does that make
                any sense? If it does, you don't need to read any further. If it
                doesn't, then read on and see if this helps.

                I use plastic or silnylon as a vapor barrier between my hammock and my
                SnugFit Underquilt. The suspension system on the SnugFit helps keep
                the vapor barrier against the fabric of the hammock to minimize air
                gaps that would encourage insensible perspiration to condense and
                pool. With the vapor barrier held in place against the underside of
                the hammock fabric, the hammock fabric wicks away any slight buildup
                of insensible perspiration where it can more easily evaporate and I
                usually don't even notice it. I pick when I do that and understand how
                to use it. It is been very effective for me at extending the lower
                temperature range that I can use my underquilt. I would not use a
                vapor barrier when I was using the underquilt in warmer conditions
                because then I would be dealing with sweat and there would be larger
                amounts of sweat/moisture to deal with as the vapor barrier would
                cause me to overheat even more and prevent moisture from sweat from
                passing through the breathable underquilt.

                In general, breathable insulation works best when your insulation is
                getting too warm for you and less breathable insulation works best
                when your insulation is not quite warm enough for you. That has
                everything to do with how, when, and why your body produces sweat (or
                sensible perspiration) and insensible perspiration.

                Your body produces sweat to help cool off at the outer surface of your
                skin with evaporative cooling when you overheat. Your body does not
                produce sweat when you are not overheating... you don't just leak
                water through your skin all the time. When you are not sweating, your
                body can produce insensible perspiration to keep your skin from drying
                out. If your skin is moist enough, or not too dry, your body doesn't
                produce insensible perspiration because it senses that it doesn't need to.

                It takes energy for your body to produce insensible perspiration. When
                you are not overheating and your skin is not producing sweat, a vapor
                barrier will cause your skin to quit producing insensible perspiration
                after some period of time. Your skin quits producing insensible
                perspiration because the vapor barrier creates a high humidity
                environment by trapping the moisture from your previous insensible
                perspiration. When this happens your body does not use energy to
                produce that insensible perspiration anymore and can use that energy
                to help keep you warmer. It a sense, your body becomes a more
                efficient furnace.

                A vapor barrier is not so good when used at the wrong time or when
                used incorrectly. When you are overheating and using a vapor barrier,
                your skin continually produces sweat as a means of cooling off via
                evaporative cooling. The vapor barrier prevents the evaporative
                cooling because the sweat is trapped by the vapor barrier. You just
                keep sweating and moisture can build up. You need to do something to
                keep from overheating because what your body is doing isn't working
                because of the vapor barrier. You need to remove the vapor barrier,
                vent, or remove insulation.

                When you use a vapor barrier with breathable insulation between it and
                your skin, that breathable insulation is subject to getting moist or
                even wet from insensible perspiration. The insensible perspiration
                will initially pass through the breathable insulation and stop when it
                hits the vapor barrier. This continues until the humidity builds up
                enough for skin to quit producing insensible perspiration. But until
                that happens that breathable insulation is going to be getting moist
                too. What you want is a thin wickable sheet of fabric between you and
                the vapor barrier such that it can wick any slight moisture buildup
                away where it can evaporate into the surrounding air. Of course it
                helps for the surrounding air to be able to absorb that moisture
                because if it can't, it won't and you will be clammy.

                And of course, if you use breathable insulation between you and a
                vapor barrier while you are overheating, you will soak that breathable
                insulation with sweat (sensible perspiration). That is bad and that
                happens when people don't understand how and when to use a vapor barrier.

                When closed cell foam pads are used with breathable underquilts in
                hammocks, we get a situation where the overall insulation is greater
                than the sum of the various components making up the insulation. That
                is because closed cell foam pads are also vapor barriers. The vapor
                barrier stops your body from producing insensible perspiration and
                causes the breathable underquilt to provide more apparent insulation
                (although it isn't doing anything different) because your body is now
                operating more efficiently at keeping you warm. If you use a ccf pad
                that provides 20F worth of insulation with a breathable underquilt
                that provides 40F worth of insulation by itself, you will end up with
                more than 20 + 40 = 60F worth of insulation. You might end up with
                70F worth of insulation or more.

                You can also wear a vapor barrier to help stay warmer. You can do it
                selectively for parts of your body or you can do it for your whole
                body (but don't forget you need to breathe). You can use vapor
                barrier liners for sleeping bags or plastic bags over your feet, head
                (as a hat), torso, etc or rain suits. I haven't tried a vapor barrier
                liner for a sleeping bag but have used a rain suit for a vapor barrier
                (even breathable ones work) and used plastic bags over feet, head, and
                torso with success. I always have used thin liner material under them
                with the understanding they would likely get slightly moist from
                insensible perspiration.

                Vapor barriers work well for people that know when and how to use them
                and are often problems or even disasters for people that don't.

                [I am a little conflicted about this particular paragraph. On one
                hand I feel it is important if this write up is going to be used as
                somewhat of a reference for vapor barriers. On the other hand I don't
                want to scare folks about a problem they aren't likely to encounter.
                but here goes.] Understanding vapor barriers, how to use them, when
                to use them, and when not to use them becomes more important the
                colder it gets. I don't have experience in extremely cold
                temperatures but my understanding is that if you use breathable
                insulation at extremely cold temperatures you risk insensible
                perspiration condensing inside the insulation as the dew point
                temperature moves inside the bag itself. Vapor condensing inside the
                bag creates moisture inside the bag and is just as troubling as sweat
                or any other moisture getting inside the bag. When this happens the
                insulation may not dry out at the temperatures you find yourself in
                and can accumulate over the days you are exposed to extremely cold
                temperatures. This can be a troubling phenomenon if it occurs as your
                bag can become increasingly heavier and less efficient. For most of
                us this isn't an issue as I am referring to extremely cold conditions
                and we shouldn't be concerned about the dew point moving inside the
                bag itself at the more moderate cold conditions that most of us camp
                or backpack in. I only mention it because it should be of interest to
                the few individuals that are camping or backpacking in extremely cold
                temperatures.

                Dave Womble
                aka Youngblood AT2000
                designer of the Speer Segmented Pad Extender, SnugFit Underquilt, and
                WinterTarp
                May 13, 2008
                Revised December 1, 2008





                [Non-text portions of this message have been removed]
              • Ed Speer
                Hollis, great post! Your advice to try new gear at home before trusting to the outback is right on! Thanks for reminding us of this most critical safety
                Message 7 of 13 , Jan 7, 2009
                • 0 Attachment
                  Hollis, great post! Your advice to try new gear at home before trusting to
                  the outback is right on! Thanks for reminding us of this most critical
                  safety measure.



                  I too have a tale that illustrates just how effective a simple vapor barrier
                  can be. A few winters back, hammocking at home, I awoke in the am very snug
                  & warm, but with heavy frost covering the entire top & sides of my PeaPod
                  (which is a large down insulated sleeping bag that goes completely around my
                  hammock). I was using a thin plastic sheet as a vapor barrier between the
                  bottom of the hammock & inside the PeaPod-but no vapor barrier over the top
                  or sides of me. Apparently some of my body moisture rose during the night,
                  passed thru the insulation on top of me & condensed on the outer shell of
                  the PeaPod where it froze. As an experiment, I removed the plastic sheet
                  without opening the PeaPod more than a few inches. Within 3 minutes the
                  frost on my PeaPod had melted & I began to feel cold seeping into the
                  PeaPod! I think the plastic sheet worked fine, prevented loss of body
                  moisture & warmth on the bottom of the hammock & added noticeable warmth
                  overall. Upon removing the plastic sheet, more of the warm moist air inside
                  my PeaPod was allowed to rise & escape thru the top of the PeaPod quickly
                  melting the frost, even though the outside temp was still well below
                  freezing. At the same time, cold outside air below my hammock could now
                  enter the hammock thru the bottom insulation replacing the warm air inside &
                  making me cold. The plastic sheet apparently disrupted the normal
                  circulation of the warm air around my body inside the PeaPod & kept much of
                  it from rising, escaping thru the top insulation, & being replaced by the
                  inflow of cold outside air from beneath the hammock. So a simple vapor
                  barrier sheet beneath me not only worked on the bottom, but it also worked
                  on the top! I credit my simple 1mil painter's drop cloth plastic sheet (<2
                  oz) with adding 10-200F warmth! .Ed



                  Moderator, Hammock Camping List

                  Author, Hammock Camping book

                  Editor, Hammock Camping Newsletters

                  Owner, Speer Hammocks Inc



                  From: hammockcamping@yahoogroups.com [mailto:hammockcamping@yahoogroups.com]
                  On Behalf Of Hollis Easter
                  Sent: Wednesday, January 07, 2009 10:26 AM
                  To: hammockcamping@yahoogroups.com
                  Subject: Re: [Hammock Camping] Frost free?



                  Dave,

                  I've been reading stuff about winter mountaineering for a few years now,
                  and your explanation of the theory and practice behind vapor barriers is
                  probably the most cogent I've read. It matches my own experience with
                  them, too.

                  Something I might add about vapor barriers is that they're somewhat
                  different from other forms of gear in that you need some acquired
                  learning before it'll work well for you. The first few times you use a
                  VB system, chances are good that you'll get something wrong, whether
                  large or small. Maybe you've got too much insulation, so you start
                  sweating. Maybe you forget about the VB liner on your sleeping bag, and
                  you bring your wet gloves and hat inside it with you, and they're
                  sponges in the morning. Maybe... you get the idea.

                  The point being that it's never a great idea to bring new forms of gear
                  out into the field without practicing at home, but it's an especially
                  poor choice if you're just learning to use VB. Sleep out in the backyard
                  for a few nights first, where it doesn't matter if you soak your
                  insulation or get cold or whatever.

                  There's a neat trick I stumbled onto accidentally while testing my
                  Hennessy SuperShelter--it'll prove the worth of VB to you. I was
                  sleeping out in 20 F weather, with wind. I had the space blanket in VB
                  position (pressed up against the hammock body, with insulation OUTSIDE
                  it). I didn't quite snug the space blanket up properly the first time,
                  though, and there was a spot on my shoulders that didn't have VB.

                  I slept really comfortably, and didn't notice any problems (including on
                  my shoulders). However, when it came time to pack up, it was easy to
                  tell where I'd missed the VB: the open-cell foam was wet enough that I
                  could wring some water out of it. It really illustrated the point.

                  You could try that on your own by wearing rain pants to bed and then
                  looking at the difference in condensation between your legs and torso on
                  the inside of the sleeping bag... or you could tape a trash bag to half
                  the underside of your hammock. There are lots of ways to mess with it.

                  VB is a really useful trick that, like ultralight gear, requires
                  knowledge to make it go. I loved your article; have you considered
                  sticking it in the files section of the Yahoo group?

                  Best,
                  Hollis
                  On Wed, Jan 07, 2009 at 12:40:36PM -0000, Dave Womble wrote:
                  > --- In hammockcamping@yahoogroups.com
                  <mailto:hammockcamping%40yahoogroups.com> , "Ed Speer" <ed@...> wrote:
                  > >... I'd love to see vapor barriers discussed on this List for I know
                  > > many of you have tried them with varying results. ...
                  >
                  > Ed... seems like this comes up every year about this time, and for
                  > good reason. I think you, I, and a lot of winter campers use some
                  > type of material to breathe through in cold weather. I use a bandanna
                  > or some type of fleece to breathe through in cold weather to keep from
                  > getting a sore throat and to limit how much moisture I lose due to
                  > exhaling. That cuts down on the frost or moisture also.
                  >
                  > I know Ed had things to say about vapor barriers in his book on
                  > hammock camping. Over the years I have tried to keep an updated
                  > document on my thoughts about vapor barriers and it is probably a good
                  > time to re-post that. Here it is:
                  >
                  > My Thoughts on Vapor Barriers... again.
                  >
                  > Vapor barriers aren't that easy to use if you don't understand what is
                  > going on and they aren't that hard to use if you do. Does that make
                  > any sense? If it does, you don't need to read any further. If it
                  > doesn't, then read on and see if this helps.
                  >
                  > I use plastic or silnylon as a vapor barrier between my hammock and my
                  > SnugFit Underquilt. The suspension system on the SnugFit helps keep
                  > the vapor barrier against the fabric of the hammock to minimize air
                  > gaps that would encourage insensible perspiration to condense and
                  > pool. With the vapor barrier held in place against the underside of
                  > the hammock fabric, the hammock fabric wicks away any slight buildup
                  > of insensible perspiration where it can more easily evaporate and I
                  > usually don't even notice it. I pick when I do that and understand how
                  > to use it. It is been very effective for me at extending the lower
                  > temperature range that I can use my underquilt. I would not use a
                  > vapor barrier when I was using the underquilt in warmer conditions
                  > because then I would be dealing with sweat and there would be larger
                  > amounts of sweat/moisture to deal with as the vapor barrier would
                  > cause me to overheat even more and prevent moisture from sweat from
                  > passing through the breathable underquilt.
                  >
                  > In general, breathable insulation works best when your insulation is
                  > getting too warm for you and less breathable insulation works best
                  > when your insulation is not quite warm enough for you. That has
                  > everything to do with how, when, and why your body produces sweat (or
                  > sensible perspiration) and insensible perspiration.
                  >
                  > Your body produces sweat to help cool off at the outer surface of your
                  > skin with evaporative cooling when you overheat. Your body does not
                  > produce sweat when you are not overheating... you don't just leak
                  > water through your skin all the time. When you are not sweating, your
                  > body can produce insensible perspiration to keep your skin from drying
                  > out. If your skin is moist enough, or not too dry, your body doesn't
                  > produce insensible perspiration because it senses that it doesn't need to.
                  >
                  > It takes energy for your body to produce insensible perspiration. When
                  > you are not overheating and your skin is not producing sweat, a vapor
                  > barrier will cause your skin to quit producing insensible perspiration
                  > after some period of time. Your skin quits producing insensible
                  > perspiration because the vapor barrier creates a high humidity
                  > environment by trapping the moisture from your previous insensible
                  > perspiration. When this happens your body does not use energy to
                  > produce that insensible perspiration anymore and can use that energy
                  > to help keep you warmer. It a sense, your body becomes a more
                  > efficient furnace.
                  >
                  > A vapor barrier is not so good when used at the wrong time or when
                  > used incorrectly. When you are overheating and using a vapor barrier,
                  > your skin continually produces sweat as a means of cooling off via
                  > evaporative cooling. The vapor barrier prevents the evaporative
                  > cooling because the sweat is trapped by the vapor barrier. You just
                  > keep sweating and moisture can build up. You need to do something to
                  > keep from overheating because what your body is doing isn't working
                  > because of the vapor barrier. You need to remove the vapor barrier,
                  > vent, or remove insulation.
                  >
                  > When you use a vapor barrier with breathable insulation between it and
                  > your skin, that breathable insulation is subject to getting moist or
                  > even wet from insensible perspiration. The insensible perspiration
                  > will initially pass through the breathable insulation and stop when it
                  > hits the vapor barrier. This continues until the humidity builds up
                  > enough for skin to quit producing insensible perspiration. But until
                  > that happens that breathable insulation is going to be getting moist
                  > too. What you want is a thin wickable sheet of fabric between you and
                  > the vapor barrier such that it can wick any slight moisture buildup
                  > away where it can evaporate into the surrounding air. Of course it
                  > helps for the surrounding air to be able to absorb that moisture
                  > because if it can't, it won't and you will be clammy.
                  >
                  > And of course, if you use breathable insulation between you and a
                  > vapor barrier while you are overheating, you will soak that breathable
                  > insulation with sweat (sensible perspiration). That is bad and that
                  > happens when people don't understand how and when to use a vapor barrier.
                  >
                  > When closed cell foam pads are used with breathable underquilts in
                  > hammocks, we get a situation where the overall insulation is greater
                  > than the sum of the various components making up the insulation. That
                  > is because closed cell foam pads are also vapor barriers. The vapor
                  > barrier stops your body from producing insensible perspiration and
                  > causes the breathable underquilt to provide more apparent insulation
                  > (although it isn't doing anything different) because your body is now
                  > operating more efficiently at keeping you warm. If you use a ccf pad
                  > that provides 20F worth of insulation with a breathable underquilt
                  > that provides 40F worth of insulation by itself, you will end up with
                  > more than 20 + 40 = 60F worth of insulation. You might end up with
                  > 70F worth of insulation or more.
                  >
                  > You can also wear a vapor barrier to help stay warmer. You can do it
                  > selectively for parts of your body or you can do it for your whole
                  > body (but don't forget you need to breathe). You can use vapor
                  > barrier liners for sleeping bags or plastic bags over your feet, head
                  > (as a hat), torso, etc or rain suits. I haven't tried a vapor barrier
                  > liner for a sleeping bag but have used a rain suit for a vapor barrier
                  > (even breathable ones work) and used plastic bags over feet, head, and
                  > torso with success. I always have used thin liner material under them
                  > with the understanding they would likely get slightly moist from
                  > insensible perspiration.
                  >
                  > Vapor barriers work well for people that know when and how to use them
                  > and are often problems or even disasters for people that don't.
                  >
                  > [I am a little conflicted about this particular paragraph. On one
                  > hand I feel it is important if this write up is going to be used as
                  > somewhat of a reference for vapor barriers. On the other hand I don't
                  > want to scare folks about a problem they aren't likely to encounter*
                  > but here goes.] Understanding vapor barriers, how to use them, when
                  > to use them, and when not to use them becomes more important the
                  > colder it gets. I don't have experience in extremely cold
                  > temperatures but my understanding is that if you use breathable
                  > insulation at extremely cold temperatures you risk insensible
                  > perspiration condensing inside the insulation as the dew point
                  > temperature moves inside the bag itself. Vapor condensing inside the
                  > bag creates moisture inside the bag and is just as troubling as sweat
                  > or any other moisture getting inside the bag. When this happens the
                  > insulation may not dry out at the temperatures you find yourself in
                  > and can accumulate over the days you are exposed to extremely cold
                  > temperatures. This can be a troubling phenomenon if it occurs as your
                  > bag can become increasingly heavier and less efficient. For most of
                  > us this isn't an issue as I am referring to extremely cold conditions
                  > and we shouldn't be concerned about the dew point moving inside the
                  > bag itself at the more moderate cold conditions that most of us camp
                  > or backpack in. I only mention it because it should be of interest to
                  > the few individuals that are camping or backpacking in extremely cold
                  > temperatures.
                  >
                  > Dave Womble
                  > aka Youngblood AT2000
                  > designer of the Speer Segmented Pad Extender, SnugFit Underquilt, and
                  > WinterTarp
                  > May 13, 2008
                  > Revised December 1, 2008
                  >
                  >





                  [Non-text portions of this message have been removed]
                • Jeff
                  Re: vapor barriers, I agree with the earlier posts. Here s my story. One night on the Foothills trail I slept in silkweight thermals, a fleece jacket, and my
                  Message 8 of 13 , Jan 7, 2009
                  • 0 Attachment
                    Re: vapor barriers, I agree with the earlier posts. Here's my
                    story. One night on the Foothills trail I slept in silkweight
                    thermals, a fleece jacket, and my waterproof breathable rain jacket.
                    My fleece was damp in the morning. The next night in similar
                    conditions, I moved the fleece to the outside...silkweights, rain
                    jacket, then fleece. I was much warmer that night and the fleece
                    didn't feel damp. So like Ed says, even though the jacket
                    is "breathable" it's still a pseudo-VB. Makes me want to experiment
                    with VBs more b/c it seems like a very convenient way to substitute
                    knowledge for gear.

                    Of note, Warbonnet Outdoors is making synthetic underquilts and half-
                    underquilts from sil, and underquilt covers to fit over down
                    underquilts. These can act as VBs under the hammock as well.

                    I'm thinking of my next system being a half-underquilt with the inner
                    shell made of sil, a torso-sized CCF pad for under my legs, and
                    possibly a hoodless poncho that can be used as a Garlington Taco to
                    add an extra pocket of dead air space for colder nights. Any
                    thoughts on this setup?

                    Re: the original question, I use a few things to cover my mouth
                    with. Usually it's a Serius brand neofleece facemask. It has little
                    breathe holes over the mouth, and a shaped nosepiece that leaves the
                    nostrils open. Even with the holes it stops a lot of moisture coming
                    out and warms the air a bit when I breathe it.

                    When it's colder, I'll use a balaclava. I've used the both together
                    when it's really cold...not the most comfortable but it's warm.

                    Jeff
                  • Dave Womble
                    ... Done and thanks for the kind words. Dave
                    Message 9 of 13 , Jan 8, 2009
                    • 0 Attachment
                      --- In hammockcamping@yahoogroups.com, Hollis Easter <easter@...> wrote:

                      >
                      > VB is a really useful trick that, like ultralight gear, requires
                      > knowledge to make it go. I loved your article; have you considered
                      > sticking it in the files section of the Yahoo group?
                      >
                      > Best,
                      > Hollis

                      Done and thanks for the kind words.

                      Dave
                    • Dave Womble
                      ... experience plus ... people & ... Thanks for ... us. ... form of ... no-see-um bug ... does hold ... subfreezing ... trapped some ... fall back ... body
                      Message 10 of 13 , Jan 8, 2009
                      • 0 Attachment
                        --- In hammockcamping@yahoogroups.com, "Ed Speer" <ed@...> wrote:
                        >
                        > Thanks Dave, your input is most valuable. You & I have discussed vapor
                        > barriers many times & I know your understanding comes from
                        experience plus
                        > your analytical mind! Some descriptions of vapor barriers by other
                        people &
                        > posted on various sites are confusing or even outright wrong.
                        Thanks for
                        > taking the time to write down your thoughts & for sharing them with
                        us.
                        >
                        >
                        >
                        > I often say that all outdoor fabrics used for camping exhibit some
                        form of
                        > vapor barrier-some fabrics are just better than others. Even
                        no-see-um bug
                        > netting is a vapor barrier-just not a very good one. Bug netting
                        does hold
                        > in some of your body heat & blocks a bit of cold wind as seen on
                        subfreezing
                        > nights. I've even had snow inside my hammock when the bug net
                        trapped some
                        > of my expelled breath & allowed the moisture to condense, freeze &
                        fall back
                        > on my face as snow. In warmer temps, the bug net can trap enough
                        body heat
                        > & moisture to make me uncomfortably warm & clammy. So we all deal with
                        > vapor barrier fabrics each time we camp. Dave's observation is
                        correct that
                        > we'll be more comfortable when we understand how vapor barriers work
                        & how
                        > to add, remove, or vent them when needed as conditions dictate.
                        Sometimes
                        > outside temperature & humidity changes during a single night might
                        require
                        > the camper to make appropriate changes to maintain comfort. While I
                        wish it
                        > was otherwise, no one fabric or vapor barrier is magically perfect
                        for all
                        > conditions-so its camper be ware..Ed
                        >
                        >


                        Ed, I can't agree more with you about various fabrics and descriptions
                        like vapor barrier, waterproof, and breathable. Our first inclination
                        is to treat those terms as absolute... if it is a vapor barrier then
                        it is a VAPOR BARRIER and no vapor can pass through it, if it is
                        waterproof then it is WATERPROOF and no water can pass through it, and
                        if it is BREATHABLE then it is breathable and vapor will always pass
                        through it. Turns out, it doesn't always work that way. In fact it
                        doesn't with many of the materials we use- especially fabrics. There
                        are conditions (or requirements, qualifiers, etc.) that we often
                        ignore or don't even hear that affect to what degree something is a
                        vapor barrier, or waterproof, or breathable. Sometimes those little
                        details are inconsequential, other times they make a difference in
                        whether something performs the way we expect.

                        Dave
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