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. #61
    G...Hawk's Avatar
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    Thank you all for the lessons.

    This answers some questions.
    Most importantly : creates a mind set of observation and practice.



    G
    trailname : Distracted By Stone

  2. #62
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    I'm still trying to get it. I understand how it works. The VBL traps warmth, humidity and sweat near the body, keeping the insulation outside the VBL dry. But the part that is not explained well is the venting process, which apparently is required when you feel the (inevitable) perspiration. It sounds like as long as you manually vent at the moment you feel the sweat, this will keep you comfortable. I'm trying to picture this as convenient or comfortable.

  3. #63
    BillyBob58's Avatar
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    Quote Originally Posted by toddhunter View Post
    I'm still trying to get it. I understand how it works. The VBL traps warmth, humidity and sweat near the body, keeping the insulation outside the VBL dry. But the part that is not explained well is the venting process, which apparently is required when you feel the (inevitable) perspiration. It sounds like as long as you manually vent at the moment you feel the sweat, this will keep you comfortable. I'm trying to picture this as convenient or comfortable.
    That is pretty much it, I think you have got it. But you won't necessarily have " (inevitable) perspiration", if by that you mean "sweat". The body produces that insensible perspiration to keep the skin moist, or so I have read. If that moisture disappears into the air and off of your skin, it can not only produce evaporative cooling ( same principle as an air conditioner or swamp cooler), but once it is gone your body just produces more. Then more cooling and even dehydration is contributed to.

    However, inside a vapor barrier the humidity level will quickly be near 100%, and the vapor can not escape. So at that point, since the skins humidity level is at a maximum, your body stops producing this insensible perspiration. So if you maintain a just warm enough- but not necessarily cool/cold temp, you will not produce any more moisture. So you will not sweat, unless you actually overheat. It will feel a little ( or a lot) humid, but not necessarily wet.

    Unless you actually go a little further and over heat a bit. Then your body tries to cool things down by producing sensible perspiration, or liquid, aka sweat. If this happens, you have used your VB at less than expert level. Then again, if you were having a hard time staying warm, and now a little sweat is your problem, it may not really be that much of a problem. And however much sweat you produce- due to overheating- it does not enter your insulation, but stays inside your VB. Not the most comfortable situation, but maybe more comfortable than shivering and better than wet insulation. I actually suspect that people using breathable insulation sweat a lot more than they realize when they are toasty warm, And their insulation is happy to soak it up so they don't even know that they have sweated. The sweat will be uncomfortable and very obvious, but contained and kept from the insulation, inside a VB. Any hint of actual sweat ( as opposed to just very high humidity or a muggy/clammy feeling) is a sign to vent. Maybe not to vent the VB, but to vent the insulation that is on top of the VB.

    Just for the sake of experimentation, I put on a VB shirt about a half hour ago, at room temp. For about 15 minutes I have felt definitely too warm for comfort, and feel like I am on the verge of sweating. But I know from experience that if I sat outside at 60 or 65F, with a VB and no insulation, I would not sweat but would probably be warm enough. You should try such an experiment yourself, maybe with a bread sack used as a sock over a very thin layer of socks. But just remember the VB will make you warmer, so if you are already warm enough without the VB, you might sweat with it.

    After a little over 1/2 hour, mostly sitting in my recliner, I took the VB off. I instantly felt a dramatic cooling ( but felt no such thing when I took my cotton T short off to put the VB on), but I found no signs of sweat. Not even on my back which was pressing into my recliner. But if the room had been even 2 or 3 degrees warmer, I'm sure I would have been sweating. But I might still take a little sweating over shivering cold and/or having any body moisture, maybe even outright sweat, getting into my insulation night after night. All depends on how cold it is and how long I'm going to be out.

    I don't think it will ever be as comfortable as a breathable system, assuming you are warm enough in that system. But it can have dramatic warmth benefits for the weight and thickness, as well as keep your bags loft from getting a little lower every day under the right conditions. My rough guess of the temp difference between my cotton t shirt at room temp vs no t shirt and my VB shirt is 10 to 20F. From uncomfortably warm with the VB, to almost a little too cool with the VB gone and cotton T shirt back on.
    Last edited by BillyBob58; 10-26-2012 at 22:49.
    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. #64
    Senior Member DemostiX's Avatar
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    What about feet?

    I'm likely not the only one whose feet perspire differently from the rest of his/her body, so the treatment may need to be different.

    I know they sweat,from the unsuitability of the popular and vapor-impermeable rubber "Crocs" for mine, the ones with thin fleece within the rubber shoe shell. Not surprised from distant similar experience, but I had to give Crocs a try because I got them as a gift from someone eager for me to appreciate them.

    Just sitting around indoors, the fact that my feet had sweat-loaded the fleece was apparent from the evaporative cooling from the thin socks I was also wearing any time I slipped out of the Crocs, as well, of course, as from the damp of the shoe liner.

    So, do any regular users of VBs have to make an exception for their feet? BillyBob?

  5. #65
    New Member RED531's Avatar
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    thanks for all the info

  6. #66
    New Member ukarcher's Avatar
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    Great thread guys.
    for some years i've used the same cold weather format. Lycra (spandex) shirt and pants next to my skin, with cheap rubberised waterproofs as my VBL. (Jacket is tucked in my pants, and the wrists and ankles are elasticated to form a seal.) I don't use a VBL on my hands or feet, (just wool socks) as they seem to stay cool enough to regulate themselves. A wool hat completes the ensemble. I use a 3 season down bag with a full-length zip as my TQ, and a thermarest underneath. if its particularly cold, I use a folded sheet of closed cell insulation which is used for under laminate floors here, and can be cut to fit even the widest hammock. This and the thermarest go between the layers of my WBBB. With this set-up, I've happily camped in temps to -8c. In the morning, (or for midnight excursions) I stay warm, and my body feels comfortable. As anyone who wears spandex will know, when I take off my waterproofs to dress for the day, the spandex quickly dries out in the time it takes to shake out my fleece and walking pants. And unless there is a chilly wind blowing, this doesn't feel like i've been suddenly drenched in icy water.
    I hope this helps anyone thinking of giving VBLs a try.

  7. #67
    BillyBob58's Avatar
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    Quote Originally Posted by DemostiX View Post
    I'm likely not the only one whose feet perspire differently from the rest of his/her body, so the treatment may need to be different.

    I know they sweat,from the unsuitability of the popular and vapor-impermeable rubber "Crocs" for mine, the ones with thin fleece within the rubber shoe shell. Not surprised from distant similar experience, but I had to give Crocs a try because I got them as a gift from someone eager for me to appreciate them.

    Just sitting around indoors, the fact that my feet had sweat-loaded the fleece was apparent from the evaporative cooling from the thin socks I was also wearing any time I slipped out of the Crocs, as well, of course, as from the damp of the shoe liner.

    So, do any regular users of VBs have to make an exception for their feet? BillyBob?
    Demostix, these bumps brought me back to this older thread, which made me realize I had eiher just missed your post or just forgot to answer it. Sorry bout that!

    But I don't know how useful of an answer I can give. It is just going to require personal experiment which you may have already done by now.

    But, no, I don't have to make an exception for my feet, at least not when sleeping or sitting around camp. I have never hiked with them yet, but I bet Fronkey has. But my feet have often become damp, more so than my torso when just sitting around in a VB shirt or pants.

    I was in my HHSS the other day at a ridiculously cold feeling ( considering it was only 43F not minus 10 but felt cold! ) temp. I started out in a VB shirt with a light insulated jacket and that is all I needed on top while I was out, very toasty. But I noticed my feet felt sweaty in my UQ and nylon socks before i decided to add the VB socks. They still felt sweaty with the VB socks of course, but it was no worse.

    Back later, got to go eat!
    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

  8. #68
    BillyBob58's Avatar
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    OK, I'm back. So, about Demostix's question:
    So, do any regular users of VBs have to make an exception for their feet? BillyBob?
    Like you, I sweat in Crocs every time, which I mostly wear without socks. But this has not caused me problems in using VB socks, which is the main form of VBs which I have used, on and off since the early 80s. I learned about VBs from Patagonia catalogs from that era. Back in those days they did not make any breathable rain gear at all.

    And it is not that my feet never get wet using these VB socks, because they do, even if more sometimes than others. But it is still warm, and keeps the footbox of my TQ dry. There have been times when I was very aware of the wetness. The first time or two it really freaked me out, because when I felt the wet my subconscious probably screamed " look out, cold feet and wet insulation is right at the door!". But the cold never appeared, in fact I was probably always noticeably warmer than without, although sometimes with an unpleasant wet sensation. I learned to ignore it if I was in need of the VB effect.

    About the wet socks and Croc lining: in the case of VB liner sock or clothing ( or maybe bare skin ) it is sacrificed to the wet. That is why it is thin a layer as I can find. It's primary purpose is to reduce the unpleasant sensation of wet coated waterproof fabric on my skin. But some times, especially feet, this layer gets wet and I just ignore it. ( but no layer used with my current VB socks which are lined with "fuzzy stuff".

    I have not noticed being wet or even damp wearing my VB shirt lined with fuzzy stuff except one day doing yard work and going up and down stairs into the attic. Sitting around at room temp or wearing the shirt under a Packa rain gear while walking as fast as possible in a cold rain, no sweat noticed.

    About this last time in my HHSS and my feet were feeling clammy inside the footbox even without a VB, just nylon socks then not much worse when I put the VB socks on: makes me think about the time the Backpackinglight folks had a lot of trouble with the footbox ( and only FB ) of their down bags collapsing. With no exposure to external moisture. It also makes me think of the time the foot of my bag and foot of the HH pad ( and no where else ) were soaked with condensation the time I did not use the space blanket. Do the feet put out more moisture ( either sweat or vapor ) , even when it is cold, than the rest of our bodies? Does this account for a lot of the cold feet people get with thick wool socks and several inches of down around their feet? Due to all of this evaporative cooling in the feet plus that moisture getting into the down? If so, would a VB sock stop all of this, even if it gave you wet feet under the VB?
    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

  9. #69
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    I guess I'm just not as smart as I wish I was. I've read this a couple times, but still don't have a technical understanding of when/when not/where understanding in specific terms of use/not use, a VB.

    What I've done in the past and understand is: below, insulate, and if a VB is used, have insulation between body and VB. On the whole, you can't insulate too much below. Above, insulate, and keep VB well above body, if used at all. Most important, stop the air from moving around.

    Its general, but I don't have a better grasp.

  10. #70
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    I'm really glad to see this being discussed as I've always figured VB's are the probably one of the few options for me to really get down into cold temps since I'm such a cold sleeper. Back in 2007 when I was going through GSMNP, a huge snow storm came through and we had 15 miles to go to get out of the park, and my feet were freezing from the trail being flooded with cold wet rain/snow/slush, so I had two thin newspaper sacks and decided to use them as a VB to keep my feet warm (never tried it before, just remember having read about it). I put the sacks on over my bare feet, then my socks over that and then my shoes. I was hiking in slushy freezing cold snow and my feet were totally warm UNTIL the thin plastic bags finally got small holes in them and then my feet were instantly flooded with freezing icy water. Talk about a shock to the system. Ever since I used those VB's I've been curious a/b them for sleeping in cold temps.
    This is my signature.

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