Vapor barriers -what is your opinion?

[BillyBob58]

I've been hanging a bit for the past year and a half. A couple dozen nights, six with temps below freezing. I have a 0 degree HG UQ and a 0 degree sleeping bag left over from my ground dwelling days. I also have an optimistically rated 20 degree TQ (a modified Costco quilt from Hang Tight on Etsy) which I've used as low as 23F but been cold even with a down jacket. I want to try the 20 degree TQ and see if I can stay warm. Extended forecast is for around 20.

OK then, sounds like you have been around a bit. So, you were cold in your TQ at 23f even using a down jacket, right? And you want to try it now at 20F with a VB, to see if you do any better? Great, sounds like the perfect experiment. The only trouble is if you are still wanting to make use of that down jacket. That very well might get damp inside a VB liner, and I suppose you don't have any VB clothing? Unless, you have some non-breathable rain gear that you could wear over your long johns but under your jacket and TQ? Or maybe rain gear on top and a VB sack on the bottom as a TQ liner?

Surprisingly, more than one person has reported using breathable rain gear as VB clothing. And they have reported some pretty good results that seemed to indicate a significant VB effect. Apparently WPB rain gear is not all that breathable, especially with an insulated layer over it. One of these was kwpapke on his minus 26F trip with Shug years ago. He reported that his quilts were much drier compared to when he did not do that. On my coldest night ever, I used true VBs on my torso and feet. On my legs I wore what are claimed to be waterproof/breathable (TNF Hydrovent) rain pants. All I can report is that my quilt above my legs appeared just as dry as anywhere else, which is to say: very dry.

Possibly, if in a VB bag liner(large garbage or leaf bag?), could you drape the jacket over you, on top of the VB but under the TQ, or on top of the TQ? But, keeping it in place probably would be a challenge. If you try it, let us know if it seems to help, or not.

[BillyBob58]

Vapor Barrier experimentation

I have been reading the vapor barrier discussions both past and present with a morbid fascination. When I first came across it my thoughts were “What kind of idiot wears a sweat suit in the winter?” Yet, as my reading continued there were nuggets of information that slowly sunk in. BillyBob58 is nothing if not persistent. There was anecdotal evidence, there was use of VB’s by Andrew Skurka. Maybe I was missing something.

Finally while reading this thread it finally sunk in. It is the evaporative cooling element that got me to thinking this could work. Sure, containing the moisture keeps your insulation dry, but what I saw as a great value was stopping evaporative cooling. I think the reason it took so long to understand this was that I never thought of evaporative cooling in a cold environment. But the laws of physics do not suspend there self just because it gets cold.

Since we had a nice cold front rolling in, tonight was the night to test the theory. Since no sane person actually owns vapor barrier clothing, I made due with Frogg Toggs top and bottom. My base layer was LL Bean long silk underwear, then the Frogg Toggs. I wore a cotton/polyester blend cargo pants, an 80% wool sweater from Goodwill, and a Gerry 650 fill down puffy. On my feet I decided that since I have two of them, I can conduct a controlled test. On my right foot I wore a Shower Pass waterproof sock with a Heavy Wigwam wool sock over that. On the left foot was a thin wool sock covered by the other Wigwam sock. On my head I wore the Frogg Toggs hood and a Carhart cap/balaclava.

My sleeping rig is a JRB Bear Mountain Bridge hammock, JRB High Sierra Sniveller TQ (5*), Greylock 4 UQ (0*), and for good measure a Thermarest pad (R-3.4) in the sleeve of the hammock. Because it was windy and there were light flurries at the time I was setting up I also used the 2QZQ under quilt protector. All this was covered by a 10 x 10 Etowah tarp with custom panel pulls.

The experiment started at 7pm, 21 degrees. I set up camp and built a small fire. To ensure I had some overnight pee breaks, I had a few adult beverages. During the camp fire phase, the true value of the VB system became apparent. Normally at that temperature, and getting colder, I would have worn another layer. Usually a 200 or 300 weight fleece jacket I have or another down coat. With the VB system I didn’t need it. This means that on a backpacking trip I can leave that extra layer of bulk and weight at home and still be quite comfortable. I also noticed that I did not get a cold butt while hanging around the fire like I usually do. So far, I was impressed.

At last it was time to hit the hammock. By this time, it was down to 17 degrees. I took off the puffy but wore everything else. I also added a rather skimpy down hood that has proven effective for sleeping in the past. I settled in and went to sleep. By 1:30am I had two pee breaks and I was no colder doing it than any other night. When I got up in the morning to get ready for work it was 9 degrees, my new personal best, and other than my nose and left foot, everything was warm and dry. No frost, but the balaclava and opening of the down hood were rather soggy. The only things that got cold were the areas NOT covered by vapor barrier: My face (really my nose) and my left foot (which, as you may recall, was only in wool socks, not the waterproof VB sock).

BillyBob58, I hereby apologize for anything I may or may not have muttered about your intelligence and good sense regarding vapor barriers. Now I will be investing in some of those sexy Warmlite VB clothes.

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It got too cold for my outdoor thermometer so I got a reading from my indoor thermometer.
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Originally Posted by Elmer003

Vapor Barrier experimentation

I have been reading the vapor barrier discussions both past and present with a morbid fascination. When I first came across it my thoughts were “What kind of idiot wears a sweat suit in the winter?” Yet, as my reading continued there were nuggets of information that slowly sunk in. BillyBob58 is nothing if not persistent. There was anecdotal evidence, there was use of VB’s by Andrew Skurka. Maybe I was missing something.

Finally while reading this thread it finally sunk in. It is the evaporative cooling element that got me to thinking this could work. Sure, containing the moisture keeps your insulation dry, but what I saw as a great value was stopping evaporative cooling. I think the reason it took so long to understand this was that I never thought of evaporative cooling in a cold environment. But the laws of physics do not suspend there self just because it gets cold.

When I got up in the morning to get ready for work it was 9 degrees, my new personal best, and other than my nose and left foot, everything was warm and dry. No frost, but the balaclava and opening of the down hood were rather soggy. The only things that got cold were the areas NOT covered by vapor barrier: My face (really my nose) and my left foot (which, as you may recall, was only in wool socks, not the waterproof VB sock).

BillyBob58, I hereby apologize for anything I may or may not have muttered about your intelligence and good sense regarding vapor barriers. Now I will be investing in some of those sexy Warmlite VB clothes. ..................

Elmer, coming in from my own VB testing, I almost spit my coffee out reading your comments about my probable imbecility! And I know it is true, I think there are more than a few here that question my sanity because of a few of my opinions that, shall we say at a minimum, do not agree with the conventional wisdom. And I actually understand that, because even though I think science supports some of my theories and experience(I have been playing with VBs since 1983, first time I got the nerve to try some socks), they at the same time go against almost everything we have been taught about the holy grail of breathability. How can two opposites be right? Well, maybe they can, depending on conditions and needs. And I will still choose nice and breathable when conditions allow. But I also know that under some conditions- maybe I'm having trouble keeping warm, maybe my loft is starting to decrease and there are many more days on the trail with no possibility of drying- a VB can be my best solution. Maybe even better than adding additional thicker, heavier, bulkier, more expensive insulation. All of us who have ever slept out under the stars, and awakened to find our bag/quilt covered in thick frost or dew(even if the ground is not) know this intuitively. That is our insensible perspiration, which has evaporated and cooled us down, that has now traveled far enough from our bodies and condensed back into liquid or ice. Do people really have that much confidence that all of that condensation has taken place on the outside of their breathable DWR quilt shell, and none just a 1/4" inside? Really? Well, in my experience, if they do believe that, after enough days on the trail, the decreasing loft of their down quilts will maybe convince them otherwise.

But looks like you have decided to do the sciency thing and PUT IT TO THE TEST! And it appears that for your experiment, the science has worked as theory had predicted. Welcome to the science nerd club!

Somewhat related: when I first started playing with Patagonia VB socks, it was 1983 in the mountains of northern AZ, when I lived in Flagstaff. They were an immediate huge help with my cold feet as well as a buddy's cold feet. At least once, they saved the day. Shoot forward 30+ years to HF, and a young man who wrote a book on hammock camping "The Ultimate Hang", starts a thread here on VB theory. Derek Hansen, aka Dejoha. Some months after that thread, he is on a hike and realizes he is going to have an unpleasantly cold sleep, despite gear rated for the temps. He remembers what he wrote about VBs, and since chance of rain is about zero, he decides to PUT IT TO THE TEST! And wraps up in his tarp, under his quilt. Result: a very warm and comfy night. VBs saved the day(or night)! And where was this? In the mountains of AZ, I think in the San Fran Peaks outside Flagstaff.

Anyway, welcome to the club, brother! (it will likely remain a small club though)

I am repeating these older comments on this thread because I stumbled on them and just realized something: for unknown reasons, when I clicked "reply with quote" on Groundskeeper's humorous (sp?) post, it showed up as having been written by "Elmer003". I don't know how that happened, and did not realize it had happened at the time. So I responded to Elmer, when I apparently should have been replying to Groundskeeper. So a belated for Groundskeepers - to me at least- very funny post. "I have been reading the vapor barrier discussions both past and present with a morbid fascination. When I first came across it my thoughts were “What kind of idiot wears a sweat suit in the winter?”.....................To ensure I had some overnight pee breaks, I had a few adult beverages.................". So Groundskeeper, if you are listening, I previously intended to tell you that your post #40 back in January Cracked me up!

[OneClick]

Regarding the garbage bag, I'm not sure that would work. I don't think any would fit me at 5'9". They start getting really wide instead of reaching a body's length. The xmas tree bag suggestion would work.

My VB liner is 70-some inches long, so I can get it over my entire body. When I decided not to and just pull it up to my arm pits, I had condensation on my TQ in the morning. But there's a good chance that was just my breath settling since there was no wind.

[BillyBob58]

Regarding the garbage bag, I'm not sure that would work. I don't think any would fit me at 5'9". They start getting really wide instead of reaching a body's length. The xmas tree bag suggestion would work.

My VB liner is 70-some inches long, so I can get it over my entire body. When I decided not to and just pull it up to my arm pits, I had condensation on my TQ in the morning. But there's a good chance that was just my breath settling since there was no wind.

Yeah, I guess you are right about none being long enough, unless they can find a Christmas tree bag. I guess that is why earlier some one else had suggested putting 2 bags together. But I'm not sure how that would work. Cut a hole in the bottom of one, over lap them a bit, and connect them with a few stitches? Or duct tape? Any way, good point. If you ar going to use a liner, it needs to be long enough.

I have known folks to cut arm and head holes into garbage bags and make some shirts, but still need to do something about the sleeves, though even sleeveless would get a lot of it done. But probably, the best way for someone trying it out is first to just to use whatever rain gear they have. Hopefully coated, non breathable would be best, if any one has such. If needing to buy new, that is not as cheap as I thought it would be at Amazon. But I do see some at Home Depot and WM for $10-15. But some initial testing could be done just wearing one's breathable rain gear. That apparently slows down vapor transfer enough to be useful. I have a theory that they become less breathable when worn under insulation, and of course they are already less breathable than a cotton T shirt or our quilt shells.

[OneClick]

If I ever try clothing I think I'll keep it simple and try the sauna suit someone else mentioned earlier. Something like $20 so it's worth a try.

[slugbait]

To make a vapor barrier bag, cut open the bottom of one bag and slide it over the open top of another bag so it overlaps a few inches. Tape the two bags together with duct tape along the overlapped area. On the topic of sweat, there's a theory that human skin likes to have a certain amount of moisture (no more, no less). Your brain will regulate this for you, up to a point- you still need to adhere to the old winter rule "Avoid Perspiring" and slow down. I was amazed after an overnight cross country ski campout- during which I wore a thin DIY rain suit under my clothes- that when I removed my vapor barriers I felt fresh and dry and clothes did as well.

[TxAggie]

If I ever try clothing I think I'll keep it simple and try the sauna suit someone else mentioned earlier. Something like $20 so it's worth a try.

That’s what I’ve been using in backyard tests and they work great. They’re a LITTLE heavy, but not terribly so. I’m thinking of getting a set of rain gear from Light Heart gear. They have Silpoly tips and bottoms that could do double duty as rain and VB clothing.


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[OneClick]

I do have that tyvek chem suit to try. It just seems so ridiculous, but could end up working great.

[cmc4free]

If I ever try clothing I think I'll keep it simple and try the sauna suit someone else mentioned earlier. Something like $20 so it's worth a try.

Looks like some lucky individual picked these up for 2 bucks at a flea market or garage sale.

[cmoulder]

Looks like some lucky individual picked these up for 2 bucks at a flea market or garage sale.

LOL wear those on the trail if you want people to leave you alone!