View Poll Results: Have You Used a Vapor Barrier Layer (VBL)?

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  • Yes, although my clothes/insulation got really wet!

    19 5.03%
  • Yes, I think they work great.

    74 19.58%
  • No, I am skeptical that VBL's work at all.

    30 7.94%
  • No, I've never really looked into VBL's.

    255 67.46%
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  1. #81
    New Member ukarcher's Avatar
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    BillyBob, thats a lot of cerebral candy to consume.
    It throws up a lot of questions.
    Forgive me if i wobble on.You probably considered all this years ago.

    below, though its probably the wrong terminology, i will use the expression 'dew-point'to indicate the point when vapor condenses.

    Many of the people I've dived with, came out wet. Sometimes it was through leakage, but other peoples t.shirts looked exactly like they had just been for a run. I totally agree about the 'moisture shut off switch' I think it works better/worse in different parts of the body.
    e.g. I think hands are much better at regulating themselves than feet.

    considering the drysuit.... we have body, fleece, VBL(drysuit), then cold water. Even though the water is cold, there is not a big enough temperature change to induce the vapor to condense.

    thought...the VBL micro-climate only works if you seperate it from the dew-point by using warm insulation. So, if we had no top quilt, then the warm vbl would be in direct contact with the cold air, causing an immediate dew-point, condensing the vapor to water, and collapsing the micro-climate.

    With a cold drink on a warm day, we get condensation of moisture from the warm air on the outside of the can/bottle.

    tin foil wrapped around an ice-cube in a warm room will collect moisture on the outside. I believe this is not from the melting ice-cube, but from the moisture in the warm air condensing at the dew-point on the foil. If we put insulation between the ice and the tin foil, there will be no condensation on the tin foil.

    I would venture to say that wearing a VBL at room temperature should not cause wetness, unless you overheat, as there is no dew-point to condense the vapor inside into water.

  2. #82
    Senior Member d-p's Avatar
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    Vapor Barrier?

    Hangers,

    Just bumped into this vapor barrier thread.

    Give www.dplightweightbackpackinggear.com "bedroom" page a look because our sleeping bag and under-quilt engineering uses the VB principle, if you keep the coated material closest to one's body?

    Coated material "outside", away from your body's heat? The VB priciple won't work as well.

    But, On the other hand, the coated material on the outside, farthest away from one's body, can be used as a rain coat ...

    dp wanting to keep one's gear as lightweight as possible, believes the vapor barrier is a good deal ...

    Happy Trailzzzzzzzzzzzzzzzzzzzzzzzz
    dp Dave
    dplightweightbackpackinggear.com

  3. #83
    BillyBob58's Avatar
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    Quote Originally Posted by ukarcher View Post
    BillyBob, thats a lot of cerebral candy to consume.
    It throws up a lot of questions.
    Forgive me if i wobble on.You probably considered all this years ago.

    below, though its probably the wrong terminology, i will use the expression 'dew-point'to indicate the point when vapor condenses.

    Many of the people I've dived with, came out wet. Sometimes it was through leakage, but other peoples t.shirts looked exactly like they had just been for a run. I totally agree about the 'moisture shut off switch' I think it works better/worse in different parts of the body.
    e.g. I think hands are much better at regulating themselves than feet.
    Curious, were they still warm, even though at least somewhat wet?

    Also wondering: do you guys, while diving in drysuits, ever get hot enough to sweat?

    Is there a "wetsuit"? if so, what is the difference?

    considering the drysuit.... we have body, fleece, VBL(drysuit), then cold water. Even though the water is cold, there is not a big enough temperature change to induce the vapor to condense.
    But, if it was condensing- or even if not - I'm thinking once a certain humidity ( as always if NOT overheating and sweating) is reached, the body will stop producing vapor at the skin, vapor which might then condense? And probably at this point there won't be enough moisture to interfere with the insulation of the fleece? So you stay warm enough? I have absolutely no knowlege, other than what has been discussed here - of how dry suites work. In fact, I have always been curious about that.


    thought...the VBL micro-climate only works if you seperate it from the dew-point by using warm insulation. So, if we had no top quilt, then the warm vbl would be in direct contact with the cold air, causing an immediate dew-point, condensing the vapor to water, and collapsing the micro-climate.
    Agreed! But, back from the oceans to the hammock, any insulation I have on the skin side of the VB will be very thin and minimal, to be sacrificed as far as insulation goes, more or less. It is only to make the VB feel better by not being in contact with my skin. But once again, even if the dew point is reached, the humidity is ( hopefully ) high enough that the body stops production of more vapor, so you only get so wet, and the wet can't evaporate ( so no evil evaporative cooling) and can't get into your real insulation. But going back to the dry suit example, it might be that with wool and synthetic insulations, if it only gets a little wet before the "vapor production switch" is turned off, maybe there will actually be even a hint of insulation still available from that next to skin layer. I just don't know!

    With a cold drink on a warm day, we get condensation of moisture from the warm air on the outside of the can/bottle.

    tin foil wrapped around an ice-cube in a warm room will collect moisture on the outside. I believe this is not from the melting ice-cube, but from the moisture in the warm air condensing at the dew-point on the foil. If we put insulation between the ice and the tin foil, there will be no condensation on the tin foil.

    I would venture to say that wearing a VBL at room temperature should not cause wetness, unless you overheat, as there is no dew-point to condense the vapor inside into water.
    Sounds good to me UK, as good a bunch of theories as any other! I'm not enough of a scientist to be holding forth on this stuff. ( And yet I am any way, right? )

    But we are about to get what should be the final word, from extensive in the field testing of VB clothing by one of our own, Fronkey! The theories make for interesting conversation. But I can't wait to see the real world results, whether good or bad, the pros and cons!
    For I consider that the sufferings of this present time are not worthy to be compared with the glory that is to be revealed to us....that the creation itself also will be set free from its slavery to corruption into the freedom of the glory of the children of God. For we know that the whole creation groans and suffers the pains of childbirth together until now.
    Romans 8:18,21-22

  4. #84
    New Member ukarcher's Avatar
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    Billybob, The drysuit comes in two types, Neoprene suits with built in silicone seals at the wrists and neck (the boots are built in), and membrane suits, which are waterproof nylon, also with silicone seals at wrists and neck. Underneath, you would usually wear a coverall suit of fleece or other insulating material. Usually, the diver stays nice and warm, (even if he gets a little damp). I dive in the North Sea, where the temperature ranges between 6c and 17c. As scuba is not a particularly energetic sport, (unless you're shore diving, and have a long walk to the water) its usually quite easy to maintain your temperature. I have simplified this a little as there are "dump valves" for getting rid of excess air from inside your suit, and an inflater valve to put some air in if you are getting "squeeze" from the water pressure. Once you have arranged this to your satisfaction, there is very little adjustment to be done. Anyway, thats how the suit works, so for the majority of the dive, all your body vapor stays sealed in there with you. So it tends to be beginners who are working hard that come out wet. I usually come out warm and dry, except for my cold fat lips, that were in direct contact with the water.
    Sorry for wobbling on again.
    I look forward to seeing what Fronkeys findings are

    p.s. the wetsuit is neoprene but not sealed, and a thin layer of water lines the inside, to be warmed by your bodyheat. It isn't really an option for diving.
    Last edited by ukarcher; 03-07-2013 at 21:22. Reason: added information

  5. #85
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    This is a quick simple and very helpful illustration. Thanks!

  6. #86
    Scout620's Avatar
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    Good article. Thanks

  7. #87
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    Good article. Check out DuPont - Tychem QC. Tyvek coated suits.

  8. #88
    New Member OneFoot's Avatar
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    Thanks a bunch for the great info.
    Keep close to Nature's heart... and break clear away, once in awhile, and climb a mountain or spend a week in the woods. Wash your spirit clean.
    John Muir

    http://youtu.be/jVjaq89-6I0

  9. #89
    Clockw3rk's Avatar
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    Your illustration style is a favorite of mine. Easy on the eyes and seems to lowers the blood pressure as you read. The information is concise and invaluable.
    At least it was for me. Thanks for the thumbnail/gif too!
    “Perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away.”
    ― Antoine de Saint-Exupéry, Airman's Odyssey

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