Hi all. I keep reading about 'vapor barriers' being used inside sleeping bags. I've never used one and would like to know more about them. Is this a simple 'plastic baggie' that goes between you and your sleeping bag to keep the moisture your body gives off from soaking into the insulation of the sleeping bag? If so, is it a comfortable way to sleep? Forgive me, but I envision waking up in a

Some folks here use vapor barriers. I did, and found a different system. Basically, it does keep body moisture from venting through ( and reducing the loft) of the insulation and bag. This also keeps in the warmth that would be wicked out . Does it work? Yes, very well. My complaint was leaving the bag in a sauna like sweat and hitting the cold morning air. A good website that compares systems and materials is www.wiggys.com If you have a present system a add on vapor barrier is a good investment. I did this with the premium down bag from my wasted youth. My present system from the above website uses a different mousetrap.

Vapor barriers work best at temperatures well below freezing. I make sure to air dry my sleeping bag often to remove the moisture my body transmits to it.

I went there, but do not understand what the mechanisim is that prevents ice from building up on the outter layer fabric.<br><br>it seems to me that no matter what the outter fabric is that any moisture will freeze on contact. Even if the insulation does not collect water vapor, the vapor will condense when it hit the layer of fabric that is outter most. if the bag is inside a canvass cover the canvass will freeze, if the bad has no cover the out fabric will freeze.....<br><br>it seems to me that you would still need a vapor barrier at below 0'.<br><br>When a bag freezes it does so from the out side and works in from that point. it takes a few days to get started with that process, but the insulation left frozen seals the bag with ice, and then the ice builds up to a point that if not dried the bag becomes useless.<br><br>I would like your report if at all possible, or your take if you have not yet had time to try this bag and idea out.......<br>i simply don't understand...... mac

They work just fine. Most useful at temps well below freezing - anytime the freezing isotherm is in the bag instead of in the air (the place where the temperature gradient from the warm inside and the cold outside cross the freezing point). They can be used anytime, of course, to prevent or greatly reduce moisture migration from you into the bag. As they are an additional layer, they add some to the warmth of the bag, but the real reason for them is moisture control.<br><br>They are an "aquired taste".<br><br>Regards,<br><br>Scouter Tom

Mac, I have both the Wiggy's unit and my vintage down bag with aftermarket vapor liner ( so I am not prejudiced in terms of system.) If you go to the WSI site ( listed in survival schools), Chris Janowski has a write up on wiggy bags ( he is a distributor) and his tests in Alaska. I like the wiggys primarily because they loft like down with easy maintenance. My down bag has 30 years of memories ( and stink) embraced in those feathers. It was professionally cleaned once. The wiggy can be tossed in the washer.

I read and still don't understand how the wiggleys works to prevent icing on what ever out side layer you use.<br><br>The way I see it if the bag is open to cold air with no other cover the outter fabric with freeze up and seal up at that point. if a canvass outter cover is used then the icing will be on the canvass, and the same thing even with gortex. The icing occurs where the 2 radicaly different temps meet.<br><br>I just want to understand..... I am not saying it doen not work, but that I don't see how wiggleys do work.... Mac

Mac, In all honesty I cannot explain it. Perhaps an inquiry to Wiggy's or Chris at WSI can help. Both systems work and thats what counts. We are both light years ahead of the heavy traditional cowboy bedroll I packed " out of tradition" and emotional sillyness once. The mule ( with more sense and a tradition of union activism) promptly destroyed it on a low branch.

Mac, I was able to correspond with Wiggy's today. Yes, Ice will form on the outermost contact layer. The insulating material is hydrophobic and will wick moisture to the contact layer vs. collecting ice in the loft itself. So basically the insulation remains at full usefullness. Icing OUTSIDE isn't that bad, since you are basically creating a seal, much as farmers will deliberately irrigate crops for a quick freeze during low temperatures. So, there it is; a vapor liner for units that do not wick liquid and the warm sauna effect or the Wiggy system which relies on a dry environment. Either system is vastly superior to the old canvas and blanket bedroll I had to crowbar my way out of in a freeze ;^)

Ok i get that bit just fine.... So for an extended outting for more than 10 to 15 days in -0' a vapor barrier would have some use, and would help. Sooner or later even that bag will be over come. When I was living out during those 3 years I used wool blakets as well as down bags. it got to be -50' at night and for a bit maybe as warm as -40' at hight noon. At times everything needed sunning, to wick out mositure.... I figure any thing would need it. Thxs for the reply... Mac