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#123273 - 11/02/09 12:05 PM Re: Good Information Here Re: (VBL) for sleeping bags [Re: ringtail]
Fishnaked Offline

Registered: 01/18/03
Posts: 191
Loc: West
I have nothing scientific to add. However, I have on a number of occasions woke up in the night uncomfortably cold and slipped on my sil-nylon or plastic poncho and slept comfortably warm for the remainder of the night.

On extra cool nights, I have donned my poncho upon going to bed...and about 40% of the time, I put left over bulk-food plastic bags on my feet held on w/ rubber bands around my ankles...before going to bed.

With the exception of one freezing night that I recall, all of this has been done in temps above freezing (mid-high 30's...perhaps low 40's.

On the nights I woke up cold and donned my poncho, I start feeling more comfortable almost immediately.

I should also note that I have tried these type of VBL's over my bare skin and over light fleece. To me, the all-around comfort level is far greater when the VBL is over fleece. When I remove the VBL upon arising, the fleece is always slightly damp but dries within minutes of being exposed to the air.

I have had such outstanding results with the above that some sort of VBL is an essential part of my kit now...and I rarely encounter below freezing temps.

#123295 - 11/02/09 06:59 PM Re: Vapor Barrier Liner & accumulation in bags [Re: DJ2]
300winmag Offline

Registered: 02/28/06
Posts: 1342
Loc: Nevada, USA
Sweat and breath moisture gradually accumulates in sleeping bags over several days, regardless of insulation type. In winter this problem is exacerbated many times because bags can't be easily air dried.

This means for near and below freezing temparatures a VBL is essential to retain bag warmth AND reduce carried weight. And, yes, ya gotta wear some light poly long johns to bed inside a VBL to avoid clamminess and direct conductive heat loss.

The ill-fated Scott south pole expedition might have had some men that made it had their down "sleeping robes" been used with a VBL of some sort. Often the men had to take an hour or more just to get inside their frozen down bags.

So, yeah, for week long or more winter trip ya NEED a decent VBL. If it isn't comfortable (too clammy) "deal with it" OR if you feel too cool you likely need a warmer bag or mattress. You'll easily know which it is, of course.

I'm finally making mine this year from waterproof aluminized ripstop I got from Seattle Fabrics a while back. MUCH cheaper than ready-made VBLs and now I won't have to spend hours airing my bag before bed time and still not getting it completely dry and then still having to wear VBL clothing in the bag. VBL clothing in a bag ain't 100% efective unless ya duct tape it closed at ankles, waist and wrists!

This isn't about whether BVL "works" for you or not. That's a subjective issue. It's about keeping the d@mn vapor from accumulating in your bag and thus keeping your insulation dry and effective day afer day. PERIOD.

"There are no comfortable backpacks. Some are just less uncomfortable than others."

#123332 - 11/03/09 04:25 PM Re: Vapor Barrier Liner & accumulation in bags [Re: 300winmag]
Fishnaked Offline

Registered: 01/18/03
Posts: 191
Loc: West
Originally Posted By 300winmag

This isn't about whether BVL "works" for you or not. That's a subjective issue. It's about keeping the d@mn vapor from accumulating in your bag and thus keeping your insulation dry and effective day afer day. PERIOD.

I agree. Sorry I veered off course. My mind was on another thread about VBLs and their effectiveness....

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