Home made sleep vapor barriers

[Michael Meiser]

I've been reading up on vapor barriers and have decided to experiment with them on my short winter trips.

I've been mining the threads here for ideas for home made vapor barriers to experiment with and was hoping I could get some suggestions.

Ideas thus far are:

1) emergency mylar bivy as a vapor barrier… will probably work well but likely won't hold up for anything but the short term.

Perhaps there is some heavier source of mylar or some heavy duty mylar bivy?

I do use a mylar emergency blanket all the time for everything from an improvised mud room in the tent, sheet for spreading out my pack stuff, a layer between rainfly and tent in the snow… all sorts of things, and yet it's still inf fine shape if I need it for an emrgency. I've been using the same one for almost a year, funny how long it holds up. Still, it's a different story to sleep directly on it or in it since I'm one of those people who is always rolling over in the night.

P.S. I tend to lean toward a reflective layer but I've heard some say this is useless on a sleeping vapor barrier?

2) tyvek? seems a little stiff and perhaps even needlessly heavy as a vapor barrier. Though I think it'd make a great light weight outer shell / winter bivy since I wouldn't need my breathable gortex shell if I'm using an inner vapor barrier

3) nylon coated with spray on water proofer, i.e. a silicone waterproofer.

I'm thinking this would be the best option, it'd be tough and yet light and comfortable. My biggest issue is finding the right waterproofer. There are hundreds of waterproofers but I was hoping there might be some consensus on one that works best?

I.E. Kiwi Camp Dry
http://www.cabelas.com/cabelas/en/templates/links/link.jsp?id=0057504518573a&type=product

Granger's Tent Waterproofer
http://www.rei.com/product/794913

Nikwax tent waterproofer
http://www.rei.com/product/784627

4) some sort of ultrafine sheet, i.e. silk. The idea being I can have my vapor barrier and comfort too.

I'm planning on wearing very lightweight merino wool base layers to sleep in. So the shell need not be silken comfortable. indeed something a little plasticy and stiff might even allow me to slide in and out… or rollover inside the bag easier. It may even be a desireable quality. Not having experimented with anything yet I don't know.

As a broader question, what do you use as a vapor barrier? Home made or store bought I'm curious.

[>> Bender <<]

m m I'm no expert on vapor barriers but here is a link for 1-3 mil Mylar rolls http://www.mylarstoreonline.com/25ft.html

[Michael Meiser]

I forgot to include another option. Someone actually recommended a tyvek paint suit??

Looking a head… if you use vapor barriers during the day and at night I must ask, why need they be separate?

If cleanliness is an issue it seems it'd be pretty easy to flip them inside out, shake them vigorously to remove any instant frost, and or wiping them off quickly before sleeping in them.

In the below thread on vapor barriers someone says they a wearable vapor barrier while sleeping which works well when they get up in the middle of the night.

http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=17103

BTW, if you're using a vapor barrier during the day do you just sleep in the same ultralight base layer that you wore during the day. If not, what do you do with it? It's impossible to dry something at night below freezing… and yet if you just stick it in the bottom of your vapor barrier bag what's the point? You'd still be sleeping with the same stinky base layers you wore during the day.

[Michael Meiser]

Thanks pointer Bender. Brings up another question.

If some people do use or recommend mylar is there a specific grade of mylar they recommend?

[Michael Meiser]

Someone also mentioned Hefty trash bags as a vapor barrier which I'd initially dismissed, but then it occured to me that in the past few years they've introduced some very thin and very tough stretchable sacks which prevent tearing and are much more "supple"… meaning they'd not be like actually sleeping in a trash bag… if that makes any sense. :)

This appeals to my ultra-light sensibilities. Hopefully for obvious reasons.

Being as how I intend to wear a thin merino layer just as long as they're not crinkly I think the combination might work well.

However, the big big problem I see is how to connect two or more together end to end (as I'm 6'5").

Duct tape seems in-elegant / clunky and week. Indeed I could see just pulling it apart in the night. The bag itself can take it, but how can I make the seem as strong?

What about sewing?? Anyone have any experience sewing the Hefty Ultra Flex, Hefty SteelSak or CinchSak?

What about possibly even using some sort of heating or glue technique?

I've seen people re-seal NeoAir matt's and other such items with heat, but have never tried such techniques myself.

Epoxy would be infinitely strong but unless there is some elastic or highly flexible epoxy I assume it would just be to rigid for this application.

Silicone or rubber cement probably to week.

Surely there is some glue or binding technique that can match the toughness and the stretchiness of a heafty trash bag?

P.S. I assume it's not to much of a worry about "smothering" in one of these since it will at most come up to my chin and definitely not over my head.

BTW, am I nuts for thinking of sleeping in a trash bag? ;)

[Acronym Esq]

"BTW, am I nuts for thinking of sleeping in a trash bag? ;)"

I too have done a fair amount of research on the idea of a vapor barrier. The first conclusion I came to was that it was only really worth the trouble for temps 0 F and below. The second conclusion I came to was that a big black trash bag would be my first experiment with a vapor barrier.

I don't think your nuts for thinking of sleeping in a trash bag. I think it is a spot on first try. I'm interested in reading a report.

Since I have no plans to intentionally cross 0 F, I doubt I'll ever execute.

< 0 F is pretty unforgiving. You might consider having a back up system just in case…

acronym 12/8/2009 2:20 AM

[Open Space]

I checked into making my own out of silnylon, but really couldn't make it for less than the $22-25 that they sell for (Campmor.com). I've also made many things with Tyvek House wrap (boat cover, bivy sack, ground sheet, etc) and have found that after you wash it a few times to remove the stiffness, water does get through, particularly when underneath me due to the pressure. For me, using a VBL is a trade between carrying an extra base layer (~16 oz for midweight baselayer) versus the 8.5 oz for a VBL (long) and since I sleep in the same baselayer that I wear while hiking, I like the added protection for my [too] expensive winter bag. Also, I tend to be an active sleeper and would question if a garbage bag would hold up throughout the night.

[John S.]

Todd, can you link to what you are talking about at Campmor?

[Frank Deland]

Warmlite sells a "No Sweat Sweat Shirt" that is an excellent vapor barrier that can be worn during the day. Worn alone it has kept me warm on a 10 degree day.

They also sell the vapor barrier fabric they use in their sleeping bags.
"Aluminized urethane coated nylon" ($25 per yard)

Read about their theory of Vapor Barriers in their catalog.

[James D Buch]

You Said:
3) nylon coated with spray on water proofer, i.e. a silicone waterproofer.

I'm thinking this would be the best option, it'd be tough and yet light and comfortable. My biggest issue is finding the right waterproofer. There are hundreds of waterproofers but I was hoping there might be some consensus on one that works best?

I.E. Kiwi Camp Dry
http://www.cabelas.com/cabelas/en/templates/links/link.jsp?id=0057504518573a&type=product

Granger's Tent Waterproofer
http://www.rei.com/product/794913

Nikwax tent waterproofer
http://www.rei.com/product/784627

========================================
Some of the products are "water repellent" treatments and some are "waterproof" and what you specifically want is a "vapor barrier"…. which is sometimes the same as some waterproof coatings, but rarely is it the same as a water repellent.

I read about this recently as well and gather that it is a good sleeping bag idea for pretty cold temperatures and especially for long trips with down insulation. The idea is to prevent water vapor from condensing inside the down insulation by trapping the water vapor next to your body.

Glenn Randall, in "The Outward Bound Staying Warm in the Outdoors Handbook" describes the basic ideas on pages 12-15. For clothing he states that he does very well in regular clothing for active sports very well until temperatures reach 20F. He cites the best days for VB to be well below freezing and days where the high temperature might be 0F, -10F or -20F.

He has a paragraph on VB sleeping bag liners and says that he usually sleeps with the top of the VB open for ventilation – unless it is really cold. He cites no specific temps for the use in sleeping bags.

[Tim Marshall]

here are the campmor ones

http://www.campmor.com/outdoor/gear/Product___41364

not sure they are silnylon though, they don't have much info.

-Tim

[Scott Littlefield]

---

I checked into making my own out of silnylon, but really couldn't make it for less than the $22-25 that they sell for (Campmor.com) (http://www.campmor.com/outdoor/gear/Product___41364)

---

I'm fairly certain that one at Campmor is not silnylon. It's listed as coated nylon, and gear that utilizes silnylon is generally pretty clear about that point (it's a sell point). Either way, you could make your own cheaper with silnylon.

You can get 2nds from Noah Lamport for $3.00/yd. Their sil tends to be 65"+ wide, so three yards and you've got all you need for any size vapor barrier sleepingbag liner. Plus extra for stuff sacks.

Campmor – $24.95+shipping (probably not sil and probably heavier than what you would make)

Noah Lamport – $14.00 (3yds and $5.00 cut fee for such a small order)+shipping

Just a thought.

[JJ Mathes]

I have to ask, won't the VBL hold condensation in next to your body while you're sleeping and won't you wake up fairly wet?

[Dean F.]

As long as you're considering trash bags- instead of crappy 0.9mil Hefty bags, go to Home Depot or a hardware store and find 3.0mil contractor-grade trash bags. They tend to be very large, which is a bonus.

JJ-

Well, yes. You can wake up very wet if you misuse a VBL. But the idea is that in extreme cold (when you are not really sweating) they hold in the water vapor that is insensibly lost directly through your skin. Thus the vapor pressure of water in the bag gets very high, and no more insensible evaporation is lost. This cuts WAY down on evaporative heat loss, which can be significant in extremely cold and dry weather. As a bonus it also keeps that water vapor from freezing into frost INSIDE the down of your sleeping bag, which is a real annoyance.

[Mary D]

Aren't those contractor bags pretty heavy? And noisy when you turn over? They would be a good option for experimenting with vapor barriers, though, if you have another use for the bags.

I have non-breathable (silnylon) rain gear (I don't find "breathable" rain gear breathable enough anyway) and use that as a vapor barrier inside my sleeping bag in below-freezing weather. The nice thing about that option is that if the temperature gets down to or below the lower limit of my sleeping bag, I can put on insulating clothing over the vapor barrier. You wouldn't want to do that inside the vapor barrier because the insulating clothing would get wet!

[JJ Mathes]

Dean- if I understand you correctly the use of VBL is best used in "dryer" climates like in the west, NOT in the eastern US where humidity is high.

If this is correct then is it not advised to use a VBL for sleeping in cold and humid climates?

[Brad Groves]

I've never awakened drenched. Moist, sure. But nothing crazy. I just keep those layers on when dressing and let my body heat dry them (wool or synthetic, takes ~15-20 minutes). I've never gotten more than a few drops of water out of my VBL. Of course, I don't use them in warm weather, either.

If you use a VBL liner (ie not VBL clothes) and get too cold, you just drape your down jacket/vest/etc over you like a quilt. I do it between the VBL and sleeping bag, which seems to keep the jacket in place.

[Jan Rezac]

Some of the materials you've listed won't work:
Tyvek is quite breathable, I more or less comparable to e-vent.
The "waterproofing" for fabrics is in fact just a water repellent, so the fabrics stays about as breathable as before the treatment.

If you want something fancier than trash bags, what about heatsheets? More durable than mylar blanket, less noisy but more expensive.

[Tim Marshall]

I think .51oz Cuben is the way to go. Way lighter than sil, more durable than trash bags and space blankets. Yeah the cost is high, but cost is always high for the extreme edge of ultralight. The thing i like most about the idea of CUBEN VB clothes is that it allows you to use CUBEN for your sleeping bag/quilt and your insulated clothes as they no longer need to be breathable. Imagine a winter kit including all cuben insulation, very light and still very warm.

-Tim

[Lawson Kline]

I have some lightweight black nylon with a double white ripstop that is laminated with mylar and has a finish weight somewhere under 1oz sq yard. Its water resistant to 175psi and is pretty tear resistant. I built an emergency bivy out of the stuff before and it works great. I think the finish weight was 6-7 oz. I might have some laying around if you are interested.

[Lawson Kline]

Oh and by the way your application is what it was designed for. High alpine sub zero sleeping bag liner.

[Michael Meiser]

Wow, good tip.

http://www.homedepot.com/Bath-Cleaning-Solutions-Trash-Recycling-Trash-Refuse-Bags/h_d1/N-5yc1vZ1xoqZbc69/R-100200334/h_d2/ProductDisplay

55 Gallon,

# Assembled Depth (In Inches) : 22 in
# Assembled Height (In Inches) : 58 in
# Assembled Weight (In LBS) : .5 lb

.5lbs though!?

Well i guess 8 ounces isn't to bad. We'll see.

I still need to figure out some way to bind two of them together. I'm 6'5" But at least I won't need to bind together three or more.

[Shawn Forry]

Last winter I made a vapor barrier jacket from a space blanket and it turned out rather well. I went to the thrift store and found a wind jacket that I liked the fit of ($3) and then took it home and de-seemed it which gave me my pattern. Bought 1 pace blanket for like $1 at wally world and cut my pieces to size based off my pattern. The key was to use double sided tape to hold everything together. I tried various ways of sewing the mylar together, but all the puncture holes just shredded the thing when any force was applied. The tape was amazingly a very strong bond. Possibly even stronger than the mylar it's self. I even went as far to tape in elastic for the arm cuffs and waist hem as well as tape in a 1/4 length zipper for ease of getting the thing on. I used the jacket all last winter and didn't have any trouble with tears or rips. I was really surprised actually at how strong the thing was. I was really careful putting it on each night and after a few nights the silver coating had worn off in some spots, but it didn't effect it's permeability. I think it weighed around 1.5oz which is about as light and cheap as you can get. Unfortunately I don't have it with me at the moment, otherwise I would post some pics.

Hope this helps,
Shawn

PS I probably had 50+ days of use on the jacket by the end of last winter as a gauge torwards it's durability

[Eric Ayala]

Saw this at western moutaineering…

Am trying to reproduce with a space blanket I have had for 15 years which looks like this…

I am planning on just using some Super 77 and sewing.

[Dean F.]

>> Dean- if I understand you correctly the use of VBL is best used in "dryer" climates like in the west, NOT in the eastern US where humidity is high.

Not necessarily. The air can be pretty dry in winter even on the east coast, when a cold front comes through. (I used to live near Pittsburgh, and got chapped lips all the time. And I'd be shocked if you ever had 100% humidity in a snowstorm, for instance.) And such cold/dry conditions maximize evaporative heat loss.

I would suspect that almost any REALLY COLD air is going to be dry- in most practical situations. (I'm sure we could name exceptions.)

That said, I've never done more than toyed with the whole VBL concept. I'm hoping to get into more winter hiking, though.

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