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RE: [Hammock Camping] Frost free?

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  • 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 1 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 2 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 3 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 4 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 5 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 6 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 7 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 8 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 9 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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