Opinions on vapor barrier liner for sleeping bag

[mateozzz]

I had been getting annoyed with my down bag losing effectiveness over the night as it got damp and had been assuming the bag was just not breathing well, maybe due to excessive DWR (it is a Marmot Arete). I've had the problem with the fly door completely open so I don't think it is due to lack of ventilation and I don't see any evidence of regular dew on the bag.

But after googling the problem it appears the dampness is just caused by normal body humidity migrating through the bag and then condensing in the down when it gets cool enough. Then I found that there are bag liners that are vapor proof to hold the humidity in and keep the bag dry. The idea is that your body will reach a steady state and although it will feel a little clammy, it won't get too bad.

http://andrewskurka.com/how-to/vapor-barrier-liners-theory-application/
http://www.moontrail.com/integraldesigns-hoodedVBliner.php

The articles I found said it was really bad in the winter because ice crystal would build up inside the bag! Most of my trips have been in early summer or late fall where the days are 70/80 and the nights are 40/50.

Has anyone tried these? Was the discomfort of the liner worth the improvement in keeping the bag dry?

Matt

[T.S.Kobzol]

I have such liner. Occasionally I use it in the winter. It is not uncomfortable at all. I also use VB sleeping bags ... eliminates the need for a liner .

Also check out the newly.treated hydrophobic down. I think TWO has some bags from sierra designs or so merging like that.

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[Tipi Walter]

Have you ever spent the night in a down mummy bag fully zipped? It is warm, sure, and mandatory at -10F but gets a little claustrophobic. Now throw in a VBL and you'll really hate it, at least I do. On my winter trips I take a substantial -15F rated Western Mountaineering bag which is warm enough without a VBL and my morning ritual is to horizontal my bear food line and hang the bag while I'm cooking breakfast.

Even at 0F on a cloudy day the hung bag will evaporate moisture. Even after many weeks on the trail in the winter there's no reason your bag can't be fully lofted if care is taken and the bag aired out frequently. It will never be as fully lofted and dry as it is at home---hence the need to go overkill. EX: At home a 10F bag will work at around 15F to 20F---in the field on a long winter trip a -15F bag will work good at 0F.

[fiddlehead]

I agree that they (vapor barrier bags) are quite uncomfortable.
Try getting inside a big plastic bag (naked or with lightweight polypro on) and then in your sleeping bag.
Basically, that's all a vapor barrier is.
You get clammy (although warmer) and it's not a pleasant feeling IMO.

[Tipi Walter]

I agree that they (vapor barrier bags) are quite uncomfortable.
Try getting inside a big plastic bag (naked or with lightweight polypro on) and then in your sleeping bag.
Basically, that's all a vapor barrier is.
You get clammy (although warmer) and it's not a pleasant feeling IMO.

Yeah, I hate it. And then there's the midnight panic of trying to get out of both bags in a fit of suffocation. If the VBL has a zipper, well, that zipper will invariably be opposite the sleeping bag zipper and nearly impossible to find when in a crazed state.

[T.S.Kobzol]

It doesn't have to be like you describe if you think and select solutions that apply to your needs.

Some of my family members aren't as plugged into the gear choices. They spent many nights in a VB sleeping bag without knowing what it was and felt no difference in comfort.

OTOH I would agree that either choice (VB or not) will work if you use your brain.

I grew up poor on totally inferior winter gear and we still had a great time.





Yeah, I hate it. And then there's the midnight panic of trying to get out of both bags in a fit of suffocation. If the VBL has a zipper, well, that zipper will invariably be opposite the sleeping bag zipper and nearly impossible to find when in a crazed state.



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[Tipi Walter]

It doesn't have to be like you describe if you think and select solutions that apply to your needs.

Some of my family members aren't as plugged into the gear choices. They spent many nights in a VB sleeping bag without knowing what it was and felt no difference in comfort.

OTOH I would agree that either choice (VB or not) will work if you use your brain.

I grew up poor on totally inferior winter gear and we still had a great time.

There are two ways to stay warm in the winter and avoid the VBL hassle. (And I've never heard of a "vapor barrier sleeping bag", so it's really two bags in one which as noted is confining and a crappy solution when other options are available. And it's real hard to regulate temperature with a VBL---you're often too hot and wake up in a sweat).

** One way is the expensive goose down bag route. Shell out $700 for a top notch overkill goose down work of art---WM, Feathered Friends, Valandre come to mind.

** The poor route---and I used this system to stay outdoors in subzero conditions. It's called Bulk. Get a cheap synthetic or cheap down bag and throw an old Army feather bag on top, or a couple Coleman Walmart bags. Total weight will be around 8-10 lbs but you'll stay warm.

[T.S.Kobzol]

Stephenson Warmlite is a vapor barrier sleeping bag. It is no hassle at all, if you don't count paying the money for the initial purchase :-)


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[SawnieRobertson]

This is a very uneducated question: Would wearing a Frog Toggs top and bottom over the base layer and within the down bag solve the stated problem? If so, I am in a good place. Otherwise, continued shivering. Thanks.--Kinnickinic

[Tipi Walter]

Stephenson Warmlite is a vapor barrier sleeping bag. It is no hassle at all, if you don't count paying the money for the initial purchase :-)


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I would never go the Stephenson route since his 3 layer bag is still around $600 and I like simplicity so with that kind of money I'd return to WM or Feathered Friends. In fact, he is probably the ONLY company making a vapor barrier sleeping bag. For a better review (with added hassles) check out this link---

http://www.weasel.com/gear_bag.html

[T.S.Kobzol]

I have used his bags do the past six seasons. They work for me in various circumstances and I am happy with the product.

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[G.G.]

I think Swanie is on to it. You can indeed wear a vapor barrier. It may not be as affective but should reduce the claustrophobicness of a liner and reduce the impact on your bag.

[T.S.Kobzol]

Sigh

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[1azarus]

... i've been meaning to respond to this thread for a couple of days... the problem i have always had with the "concept" of a vapor barrier liner is that any clothing worn inside the vapor barrier liner will get uniformly moist -- so you need to strip down to more or less just a base layer. i always plan my winter camping so that I need to wear pretty much everything i have with me to stay warm in camp (sometimes even my sleeping bag, but that is another subject). the prospect of stripping out of my nice warm clothing to get into a sleeping bag just doesn't work for me. the clothing i'm wearing adds about 10 degrees to my sleeping bag... I'm not convinced that the vapor barrier would add more than that. not to mention i would then need to carry a vapor barrier liner and climb into it!

by the way, the clothing that i do wear into the sleeping bag does include frogg toggs. not unlike tyvek "house wrap" the frogg toggs do cut down on air movement/infiltration -- but they don't stop moist air migration. still, i don't have condensation issues with my sleeping bag, except when i close down my breathable fabric hammock sock too tightly. i do have the advantage of having a breathable underside to my sleeping bag (no pad -- just more down...) i am convinced that the biggest condensation problem is caused by the moisture that comes from my breath. when i pull my hammock sock down to my chin and leave my mouth "outside" my makeshift tent my sleeping bag is as dry as can be in the morning. when i have the hammock sock loose over me i get a little condensation. close that sock up and I have a damp sleeping bag front in the morning.

[Pathfinder1]

Hi...


I'm glad that you mentioned Tyvek. Has anyone tried it as a vapor barrier? I'm anxious to try it, but would first like to hear some opinions from others.

I have kept warm many times in my sleeping bag in cold climes, with frost appearing only on the bottom of the bag in the morning. I was not sleeping on the ground, however. The bag evidenced no dampness.

[RWK]

Enlightened Equipment has cuben fiber bags which work as vapor barrier bags but they aren't cheap

[peakbagger]

Unless there are different type of cuben fiber, I expect a cuban fiber liner would be quite noisy probably a right up there with using space blanket.

Many new folks to camping have found how effective a plastic tarp or a survival blanket over the top of a sleeping bag is at trapping moisture in the bag. They normally only do it once.

[mateozzz]

I agree that they (vapor barrier bags) are quite uncomfortable.
Try getting inside a big plastic bag (naked or with lightweight polypro on) and then in your sleeping bag.
Basically, that's all a vapor barrier is.
You get clammy (although warmer) and it's not a pleasant feeling IMO.

Hmmm...where would I find a 6 ft long plastic bag?

[mateozzz]

Maybe the best solution would be a pair of long johns with a vapor barrier on the inside - anyone have ideas how to make something like that? Then you can layer-up all you want without risking the layers getting wet. Of course in the morning, you have to strip everything off and do a lap naked around the campsite to dry off before putting on your clothes.

[leaftye]

Has anyone tried these? Was the discomfort of the liner worth the improvement in keeping the bag dry?

Yes and yes. The discomfort sort of depends. If you're clothing is somewhat damp from sweat when you get into your bag, you're probably going to feel disgusting. It helps to have less clothing because it means there's less fabric to hold moisture, and you can put your clothing outside of the VBL so it'll dry out. If you have a vapor barrier suit, you wear your clothing over the suit, and your clothing will be nice and dry in the morning. The hard part is getting out of a VBL as it's probably going to stick to your skin.

It's wonderful to use this technique to completely dry out a bag overnight after it's accumulated moisture over the course of a few moist days and nights.


I'm glad that you mentioned Tyvek. Has anyone tried it as a vapor barrier? I'm anxious to try it, but would first like to hear some opinions from others.

It's not a good choice. I know they it's often called a vapor barrier when used in homes, but it's meant to allow water vapor to escape through the tyvek while blocking liquid water from entering. It's like a bulk cheap alternative to goretex.

Also, keep in mind that people use tyvek for bivy bags precisely for this reason.


Hmmm...where would I find a 6 ft long plastic bag?

A dry cleaning bag, or a body bag. For starters, just use two lawn trash bags. Cut head and arm holes for your torso in one of the bags. This works well enough that you can stick with this unless you want something lighter, lighter and more durable, or a vapor barrier suit.






Maybe the best solution would be a pair of long johns with a vapor barrier on the inside - anyone have ideas how to make something like that? Then you can layer-up all you want without risking the layers getting wet. Of course in the morning, you have to strip everything off and do a lap naked around the campsite to dry off before putting on your clothes.

You can use the patterns from thru-hiker, but use sil nylon fabric. I got a sil nylon rainsuit from Anti Gravity Gear and let him know I intended to use it as a VBL suit so he'd make it slimmer.

Much of the moisture will stick to the VBL when you take it off. Some moisture on your skin will evaporate very quickly. Almost all of the rest will get absorbed in your clothing. Take the top off first. If you get cold after getting your top half dressed, slide back into your bag until your warm up. The legs isn't as easy. Putting on bottoms in a tent is tricky, especially if you get cramps.

[1azarus]

leaftye's advice seems to be in line with andrew skurka's -- use vapor barrier clothing which you can wear into the sleeping bag at night. i've got a stephenson vapor barrier shirt which i've used a few times and has stopped making my winter pack list. it seems to me that unless it is crazy cold or you never have a hill to climb it is just too warm to use vapor barrier clothing when walking, so i just stripped before bed, put on the vb shirt under all my other clothing, then reversed in the morning. painful. didn't seem worth the effort, and the shirt weighs too much for what i got out of it. maybe i'll reconsider and buy/try a lighter suit like the one you refer to from antigravitygear. i could also try walking slower. now, there's an idea...

[Pathfinder1]

Hi...


Large trash-type bags can be purchased from many garden and farm stores.

[Tom Murphy]

VBL keep your insulating layers dry but whatever is under the VBL gets pretty damp from perspiration.

If you want to learn what VBL are like, here is a simple practice test. Wear a bread bag between a liner sock and an insulating sock for a day.

When I winter backpack in sub-zero temps, I use VBL as described above and bring multiple pairs of liners because the liners get damp. And I bring a pair of loose knit wool socks that let my feet breath a bit overnight.

The only time I would consider using a VBL in a sleeping bag is if I was trapped or immobolized and the overnight temps greatly exceeded the capacity of my sleeping bag. Plus it is pretty miserable to get out the your VBL in the middle of the night to go pee when whatever you are wearing is damp.

[mateozzz]

These are really good comments! One other concern I have is that overnight is usually when my feet get to dry out and if I have any blisters they start to heal. If everything stays clammy I would think that would slow down and the skin would stay soft. Then there is the possibility of encouraging athletes foot or jock itch, so maybe there are a lot of things to worry about. Maybe drying the bag in the sun during lunch isn't such a hassle after all.

[mamamiapdx]

some use their silnylon based clothes as vapor barrier.