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  1. #11
    Member draugen's Avatar
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    Interresting topic, have just made myself an uq from an old sleeping bag and its probably too thin for winter use. But maybe i could try out this theory with a reflective blanket... think I'll follow

  2. #12
    Senior Member DemostiX's Avatar
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    An enduring is that the "reflective" blanket is working on the human body because of reflection. For the most part reflection is a tiny part of performance.

    That's not a matter of my word or opinion. It is the physics of it. We're not hot enough to be radiating enough so that reflection has much to do with it. Metalized plastic / Mylar has the virtue of being shiny -- we like shiny -- and of being harder than the plastic / Mylar, which makes it tougher.
    Last edited by DemostiX; 04-04-2013 at 18:51.

  3. #13
    AaronAlso's Avatar
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    This just my experience...

    A reflective blanket (I use thermaflect) taped lightly to my driducks poncho hung under my UQ has faithfully added significant warmth to the system. If need be I will drape another thermoflect (spaceblanket will work too) over my hammock ridgeline and with 3-4 pieces of duct tape attach it to the backside of the driducks, letting the otherside just drape. This combination has, for me, proven to be effective 15degF or so below the rating of the TQ/UQ. I will usually get some condensation inside the top cover blanket ( from breath no doubt) and maybe just the slightest hint of it inside the undercover, but the added warmth is undenieable.

    I'd say try it next to your body, but if that is uncomfortable it will work outside the UQ too and maybe better for you. The VBL works best in extreme cold & dry condition, like the actic, most of us don't hang in those conditions. In most of our 0-32degF outings my experience has shown that using the methodology of the constuction industry works better for me; reflective layer outside of insulating layer. It works for your house and will also work for your body.

    EDIT: After some search around the forums for sources for more reflective ripstop I keep coming across the same misconception: that a radient reflector only works if it is right next to your body. In a survival/hypothermia situtation this is 100% accurate. However, in general the radient barrier needs to be as close as possible the a heat source or thermal mass. It does not need to be next to your body unless you are the only thermal mass. Our insulation counts as thermal mass and a radient barrier outside the insulation will keep the heat stored in that mass longer than without one.
    Last edited by AaronAlso; 04-04-2013 at 20:08.
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  4. #14
    Senior Member DemostiX's Avatar
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    Quote Originally Posted by AaronAlso View Post
    This just my experience...

    In most of our 0-32degF outings my experience has shown that using the methodology of the constuction industry works better for me; reflective layer outside of insulating layer. It works for your house and will also work for your body.
    Exactly wrong for construction, especially residential. Vapor barrier, sometimes reflective, is put on the inside side of insulation. When insulation is installed the wrong way, vapor from inside condenses in the insulation, reducing its effectiveness, and much more seriously -- rotting the framing over time.

    Repeat: Shiny stuff works exclusively in the cold by being wind and vapor impermeable. Wear shiny metalic mesh in the cold, and you will accelerate your cooling. Want the full thermal winter-time benefit of a metalized-mylar "space" blanket on the cheap? Cut a head-hole in a black plastic garbage bag, and pull it over you.

  5. #15
    AaronAlso's Avatar
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    When was the last time you built a house?

    I'm not going to argue with you. I'm just to tired and getting to old for those that don't have the mind to listen or the time to verify anothers claims. We don't use vapor barriers in construction, very often anyway, what we do use is tyvek which serves as a moisture barrier from the outside elements while allowing vapor to escape. This for the exact purpose of reducing the risks of mold and rott. Tyvek is often, mistakenly, called a vapor barrier.

    http://www.ornl.gov/sci/ees/etsd/btr...ier/rb4a.shtml

    http://www.radiantguard.com/how-to-i...x#.UV6HlKMpAb0

    Radient barriers go outside of mass insulation for best results be they keeping heat out or in.
    Last edited by AaronAlso; 04-05-2013 at 03:27.
    "The more laws that are written, the more criminals are produced." - "The more laws and order are made prominent, the more thieves and robbers there will be." - Lao Tze

    "Good people do not need laws to tell them to act responsibly, while bad people will find a way around the laws." -Plato

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  6. #16
    Senior Member DemostiX's Avatar
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    "Installing Vapor Diffusion Retarders for New Construction

    In mild climates, materials like painted gypsum wallboard and plaster wall coatings may be enough to impede moisture diffusion. In more extreme climates, higher-perm vapor diffusion retarders are advisable for new construction. They perform best when installed closest to the warm side of a structural assembly -- toward the interior of the building in cold climates and toward the exterior in hot/wet climates.

    A vapor diffusion retarder installation should be continuous and as close to perfect as possible. This is especially important in very cold climates and in hot and humid climates. Be sure to completely seal any tears, openings, or punctures that may occur during construction. Cover all appropriate surfaces or you risk moist air condensing within the cavity, which could lead to dampened insulation. The thermal resistance of wet insulation is dramatically decreased, and prolonged wet conditions will encourage mold and wood rot."

    Source: http://energy.gov/energysaver/articl...sion-retarders

    To the OP: I'd repeat my earlier advice. Find out what works best for you, so don't sew anything permanently. On more recent advice. Don't spend money that may be wasted money on silvery shiny film.

  7. #17
    AaronAlso's Avatar
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    I'll take to mean you haven't actually built a house before. Please refference my edited post above. Vapor diffusion layers and radient barriers are different things that provide different functions.

    Generally dark colored non-permeable materials will serve a similar function of reflecting long wave radient heat energy. Aluminumized materials are much more efficent though and reasonably priced theae days. Gold coated materials are even more efficient but also more expensive.
    "The more laws that are written, the more criminals are produced." - "The more laws and order are made prominent, the more thieves and robbers there will be." - Lao Tze

    "Good people do not need laws to tell them to act responsibly, while bad people will find a way around the laws." -Plato

    Ephesians 6:10-17

    Hammock Forums is my social network.

  8. #18
    Senior Member cv66seabear's Avatar
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    I would like a simple answer to this as I just bought an REI Space blanket to keep my arms and toes warmer. (I have issues with a cold left side after donating a kidney to my brother - although the Drs can't detect a diference in temperature).

    Two ideas: 1. put it under my REI pad inside the hammock, or 2. Secure it underneath the hammock on the outside.

    I appreciate the talk about VBLs, and I read the information, but I'd like some real-world experiences. No UQ, this is for the night chill of the other 3 seasons. Other info - since I'm a new convert from the ground, I'm using a sleeping bag.

    Thanks for the help!
    To become Old and Wise, First be Young and Foolish.

    "A man who will not read, has no advantage over a man who cannot read." - Attr. Mark Twain

  9. #19
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    To quote myself from what I understand about what I read.

    Quote Originally Posted by c0wb0y84 View Post
    VBLs work but aren't always appropriate, so more research for your intended purpose is necessary to ensure the system will be most effective.

    So the simple answer is... Try it and see. If it works then you're good to go, and if not then try something else. Its not a great answer but it's simple.

  10. #20
    canoebie's Avatar
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    If it were me, I would put it under my pad first because I don't like it up against me directly. Check for condensate using it that way. All the way on the outside I am guessing you will get some moisture build up. That is based on my own experience, yours may vary.

    It is amazing how much variance of experience and perspective there is in the world of hanging. Most important in hanging I think is to experiment, fiddle, tinker, putz, fail, succeed. I have learned that absolutism as a perspective on this stuff is not necessarily as much fun. I find myself saying, "What if...." and it gives me some more time in the woods to play.

    Have fun with it. Try it out, you will get it dialed in and know that what works for you may be entirely different from what works for others.
    Revolution is about the need to re-evolve political, economic and social justice and power back into the hands of the people, preferably through legislation and policies that make human sense. That's what revolution is about. Revolution is not about shootouts.

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