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Topic: My current thoughts on VBLs, Vapor Barriers, after a month on the ice< Next Oldest | Next Newest >
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PostIcon Posted on: Jul. 31 2013, 6:09 pm  Skip to the next post in this topic. Ignore posts   QUOTE

'Bout 6 months ago I posted a thread asking about VBLs (vapor barrier liners) and their use in extended winter camping.  The practice helps minimize the buildup of ice within insulation (sleeping bags especially) over a long trip.

This April/May I spent a month camped on the ice in the Greenland.  It was a cold and stormy month, with temps several times reaching -35-40 with alternate "warmer" bouts of 0 to -20°F and fierce storms.  I was below 0°F every night of the trip, and never once got above freezing during the days.  I used a -40°F Marmot CWM down sleeping bag that served me well the whole trip. I never slept cold at night, although can't say the same working during the day.

Fetching dinner at the mess tent:


I brought a VBL shirt and pants for sleeping, but didn't end up using it.

Most our trip was "base-camping" (staying in one spot for a week or more between moving).  My bag was usually left out in the tent during the day, where the cold dry air allowed the ice to sublimate from the insulation through the day.  Even with frost on the bag most mornings (and there was often a lot of frost)...



... by day's end the bag was completely dry without a hint of moisture.  As such, a VBL really wasn't necessary for me.

However, there was a 3-day stretch in the middle of the trip where we were moving camp a long distance and had snowmobile issues, requiring us to relocate and break down camp three nights in a row.  My bag got packed each morning in a stuff sack.  By the morning of day 4, I definitely noticed the down insulation near the outside layer of the bag a bit "crunchy" with ice.  It was building up.  Had I spent a month doing that, it would have definitely compromised the insulation in the bag.  Luckily we sat tight another 10 days and a bout of sunshine allowed a good drying-out.

Drying gear while breaking camp in a gloriously-calm 5°F:


My conclusion on VBLs?  Very useful items, provided you'll need to pack your sleeping bag every morning and it won't get a chance to air out.  Which is the way most skiers/backpacker operate.  But if you're base-camping and will be able to let the bag naturally dry each day in the frigid air?  I'd just as soon do without, and for such a month on the ice I didn't find it necessary.

I plan to bring a VBL on future trips, and use it "as needed."  Which probably won't be often unless we plan to move camp frequently.

Folks gave great advice in that thread, so I thought I'd return the favor and give my own feedback post-trip.  Thanks a lot!



- Mike


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PostIcon Posted on: Jul. 31 2013, 6:15 pm Skip to the previous post in this topic. Skip to the next post in this topic. Ignore posts   QUOTE

Dang!  I was hopin' for an action shot of my old VBL shirt on the ice!   :(

Good to know about the bags more or less drying out during the day, as long as they're not packed up.  That was always a concern of mine.


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PostIcon Posted on: Jul. 31 2013, 6:18 pm Skip to the previous post in this topic. Skip to the next post in this topic. Ignore posts   QUOTE


(hoosierdaddy @ Jul. 31 2013, 4:15 pm)
QUOTE
Dang!  I was hopin' for an action shot of my old VBL shirt on the ice!   :(

Good to know about the bags more or less drying out during the day, as long as they're not packed up.  That was always a concern of mine.

I didn't get a lot of "changing clothes" or "sleeping" action shots either way. :D

No worries, I still brought the shirt.  And will still definitely take in the future, just in case, unless you want it back.


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PostIcon Posted on: Jul. 31 2013, 6:50 pm Skip to the previous post in this topic. Skip to the next post in this topic. Ignore posts   QUOTE

did you have the VBL clothes and  bag liner? What kind of shirt and pants are they? Some crazy pictures there, nice.

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PostIcon Posted on: Jul. 31 2013, 7:02 pm Skip to the previous post in this topic. Skip to the next post in this topic. Ignore posts   QUOTE

Just the pants and shirt.  I didn't have a bag liner, although that seems the easier/lighter option for sleeping.  In the future if I want to use it, I'll probably consider one of those.

I got a free VBL shirt from Hoosierdaddy, and just supplanted it with some pants.  But in the end, I didn't use either.  Still holding onto them though, (again, unless HD wants his shirt back :)).


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PostIcon Posted on: Jul. 31 2013, 7:28 pm Skip to the previous post in this topic. Skip to the next post in this topic. Ignore posts   QUOTE

I've had "vapor" issues in mild winter conditions, somewhat "operator error".

A winter Grand Canyon trip, breaking trail in knee deep fresh powder while descending the Grandview, then several less than sunny days without airing out a Marmot zero degree bag (stuffing the bag and on the move early, coming in late).

Third evening (night time lows around 20) I'm in the bag but never warm up. Not good. I "rewind the tape", figure out what happened (top of bag damp from body vapor) and flip the bag over ("bottom" on top of me), put on a down sweater with a hood and everything's fine. Next morning took time to get the bag in the sun.

My thoughts? I may have been "overheating" the bag, closing it up too much for the relatively mild temps.

That said, the top of the bag became nonfunctional after a mere two nights use if the owner wasn't paying attention. Down needs daily time in the sun. I'm thinking even 15 minutes might do the trick. Yep, you can stuff it "damp" but I'm sure to pull it out midday at lunch.
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PostIcon Posted on: Jul. 31 2013, 7:38 pm Skip to the previous post in this topic. Skip to the next post in this topic. Ignore posts   QUOTE

Gotcha

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PostIcon Posted on: Jul. 31 2013, 7:51 pm Skip to the previous post in this topic. Skip to the next post in this topic. Ignore posts   QUOTE

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PostIcon Posted on: Jul. 31 2013, 8:56 pm Skip to the previous post in this topic. Skip to the next post in this topic. Ignore posts   QUOTE

"where the cold dry air allowed the ice to sublimate from the insulation through the day"

I have been trying to find out just how long and at what temps it takes for that to happen.
I have seen almost instant sublimation at -40f (or thereabout) plus wind , so maybe -50/60f , that is from a couple of guys shaking their bags outside a tent (on TV...) but I know that even at around -40f it takes longer than the normal morning pack up time .(a friend has tried this)
Care to have a guess on how long it takes after each night ?

BTW, how did the tents (beside the Stronghold) do ?
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PostIcon Posted on: Jul. 31 2013, 10:27 pm Skip to the previous post in this topic. Skip to the next post in this topic. Ignore posts   QUOTE


(GoBlueHiker @ Jul. 31 2013, 3:18 pm)
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No worries, I still brought the shirt.  And will still definitely take in the future, just in case, unless you want it back.

Nope...it's yours now.  It's WAY too big for my skinny little body now, anyway! :p

Gottagamble:  It's a Stephenson No Sweat Shirt


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PostIcon Posted on: Aug. 03 2013, 12:52 pm Skip to the previous post in this topic. Skip to the next post in this topic. Ignore posts   QUOTE

Did you try VBL socks?
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PostIcon Posted on: Aug. 22 2013, 10:22 am Skip to the previous post in this topic. Skip to the next post in this topic. Ignore posts   QUOTE

I just realized I hadn't followed up on this thread, despite folks asking me several questions.

(Franco @ Jul. 31 2013, 6:56 pm)
QUOTE
"where the cold dry air allowed the ice to sublimate from the insulation through the day"

I have been trying to find out just how long and at what temps it takes for that to happen.
I have seen almost instant sublimation at -40f (or thereabout) plus wind , so maybe -50/60f , that is from a couple of guys shaking their bags outside a tent (on TV...) but I know that even at around -40f it takes longer than the normal morning pack up time .(a friend has tried this)
Care to have a guess on how long it takes after each night ?

Yeah, the sublimation in the bag surely wasn't "instant", but then again I didn't usually have to pack it up in the morning (it just laid in my tent all day while I worked), so that wasn't a concern.  How long it took?  I dunno, I'd guess a few hours, but I'm not really sure on that.  I didn't pay it much attention.

QUOTE
BTW, how did the tents (beside the Stronghold) do ?

The tents did fine, overall.  We had a zipper get irreversibly stuck on one of the Terra Nova sleeping tents during a storm (which caused some uncomfortable exits & entries from the windward side in hellacious blowing snow), but we worked around it when calmer weather arrived.  The MHW Stronghold actually almost got destroyed... it was bowed in concave on one whole side during the worst of our storms.  We had to spend a pretty dangerous hour outside restaking it (it was pretty well staked already--or so we thought--but the storm had other ideas), re-guying it, building a hefty snow wall and weighing down the interior with cargo boxes to keep it stable.  That was a surprise, given how incredibly strong that tent is.  Here's a little video clip from inside later that day (the wind was a bit calmer but still howling) while the storm blew outside.  As the tent shakes back & forth, the steam from our coffee moves accordingly:

http://gobluehiker.smugmug.com/Travel/Greenland-ACT-2013/i-7xcDbsq


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PostIcon Posted on: Aug. 22 2013, 10:25 am Skip to the previous post in this topic. Skip to the next post in this topic. Ignore posts   QUOTE


(PanatomicX @ Aug. 03 2013, 10:52 am)
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Did you try VBL socks?

I didn't.  I probably will in future trips.  It would help with the ice-boots phenomenon.  Although as long as I used the spare felt liners and swapped them out daily, it wasn't a big problem.  But still, VBL socks probably would have helped.

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PostIcon Posted on: Aug. 22 2013, 10:39 pm Skip to the previous post in this topic. Skip to the next post in this topic. Ignore posts   QUOTE

Thanks GBH
I had a look at those shots , nowhere to hide ...
Must have been fun building a snow wall in those conditions.
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PostIcon Posted on: Aug. 22 2013, 11:14 pm Skip to the previous post in this topic. Skip to the next post in this topic. Ignore posts   QUOTE

As far as stuffing damp bags into their stuff sacks prior to letting them dry out, ... Niels of Valandre' told me that stuffing a bag with damp down clusters places a permanent "set" in the down clusters and will affect the loft, until the bag is washed and dried.  Kinda like putting on a cap when your hair is wet.
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PostIcon Posted on: Aug. 23 2013, 10:11 am Skip to the previous post in this topic. Skip to the next post in this topic. Ignore posts   QUOTE


(Franco @ Aug. 22 2013, 8:39 pm)
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Must have been fun building a snow wall in those conditions.

It was.  But not nearly as much "fun" as going to the bathroom out in the latrine pit though.

We had to move the toilet box into the workshop tent (different than the mess tent) for a day, because it was too dangerous to go to the bathroom outside.


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PostIcon Posted on: Aug. 23 2013, 11:25 am Skip to the previous post in this topic. Skip to the next post in this topic. Ignore posts   QUOTE

Brings a whole new meaning to "peein' in the wind"...

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PostIcon Posted on: Aug. 23 2013, 11:43 am Skip to the previous post in this topic. Skip to the next post in this topic. Ignore posts   QUOTE

Rozie cheeks comes to mind.

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PostIcon Posted on: Aug. 23 2013, 11:48 am Skip to the previous post in this topic.  Ignore posts   QUOTE

great experience, glad we can benefit from it and from your know-how and observations.  i'm jealous.

i have used vapor barrier bag liners in the winter in the northeast for longer trips (my longest was 3 weeks in the white mountains in January) - bags don't always cooperate and dry out.  they take some getting used to, it's a damp-feeling experience at first.  but if you have a sleeping bag that has a moisture-resistant or waterproof outer shell that keeps moisture out (rime falling on the bag, spilled tea, whatever), it really makes sense to avoid moisture penetrating your insulation from inside.  

i have also used vapor barrier socks inside mountaineering boots (scarpa invernos) with moderate success.  what i don't like about VBL socks in boots is that they tend to wrinkle, and that can get uncomfortable.  it also means you're constantly trying to dry out some fairly wet liner socks.  it might be worth using them on a long trip to avoid compromising insulation, but i doubt the closed cell foam insulation in my mountaineering boots absorbs much moisture, and i usually have pretty good luck drying out boot liners overnight.
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