Frost in Arctic Sleeping Bags

Next time i’ll read the article first.  Interesting article, thanks for sharing it.

It is really interesting.  I wonder, I’ve never heard Shug complain of frost or moisture in his hammock at -40f, could it be his pod system and breath catcher?  Maybe the pod lets the quilt fully vent the moisture before it can freeze, then there is venting of the pods warm air?

Been thinking of possible solutions to this problem.  So far what i’m thinking is taking some flexible/pliable thin closed cell foam layers, putting some silicone,  spray foam, or other adhesive dots on each layer to make some air space (2/7 or so “) between them (throw in some space blankets in between a couple of the layers too), seal it up on the sides and at the front, but leave the back open and use some kind of non breathble fabric at the edge with velcro sewn on so that you can open and close it up.

Then put the foam/space blanket layers in a fabric sleeve that is likewise sewn up around the sides and front, but with the back open also with velcro to open and close.

That way, should any ice or frost accumulate in it, you can open up both the sleeve and the foam to dump it out.  The fabric/foam sleeve can be sewn to a narrower bottom layer of breathable, but highly wind resistant fabric, so a sort of quilt/bag hybrid. Meanwhile, closed cell foam and dead air space is pretty non absorbent.

Overbags and vbls

the solutions are well known

;)

ha, ha,… timely for your ideas about arctic trip

if you don’t have to compress the bag to carry it, it changes the equation totally

reflectix maybe would be good – bubble wrap with relective coating.  Or a more flexible bubble wrap material.  Those would not absorb any water.

they said fur is good.  maybe some sort of a fleece like material with really long fibers.  You could shake out frost. or just use fur.

it said that when it’s really cold, it’s almost impossible to not breath into your sleeping bag.  Maybe you need a good hood with a relatively small hole to breath through.

“Overbags and vbls

the solutions are well known”

That’s similar to what i thought and said at first, but then i actually read the article.  Turns out, it’s not so simple, and ice, frost, and moisture accumulation can still happen with VBL’s, over bags, etc.

That’s what makes it such a pain in the arse on long trips–there is no easy fix.  Though my idea (as outlined earlier) would probably work pretty well.

Maybe some/a lot of you have never seen this study, but I did and red already years ago. One thing to note is that it’s in article from 2003 with the most recent example from 1992 (or 1995 ?), so more than 20 years ago. Interesting, but it should be backed up with recent examples because a lot can happen in nearly 25 years.

Maybe I should ask a local long-time polar explorer his experience with this since his first Antartic-crossing in 1997 ?

I’m not going to the Arctic or Antarctica anytime soon Jerry.

For reflectix to work, wouldn’t you have to make it at similar temps?  Because if you made it at room temp, wouldn’t the air bubbles contract a lot when brought it to such cold temps (say -20 and below?)?

Also, i just wouldn’t trust such a flimsy material that is so easily popped in a potential survival situation.

“Maybe I should ask a local long-time polar explorer his experience with this since his first Antartic-crossing in 1997 ?”

Please do.  : )

Justin

ill repeat …. The solutions are well known by now

it seems like everyone and their husky is traversing the polar regiona for charity … If they couldnt deal with the issue there would be a lot more dead bodies around

for a good vbl article read skurkas one on bpl

for overbags read this

http://korpijaakko.com/2014/06/

The gas in the bubbles will only shrink a little.  Put some in a freezer and it’ll be close – 0 F or so.  You could also assess whether it would survive cold.

Bubble wrap is pretty rugged. Have you ever popped bubbles for fun? : )  If a few of them popped, no big deal.  If every other bubble popped it would make little difference.

To Eric:

From said article, “Internal vapour barriers and external waterproof but water vapour permeable coverings may be useful in some conditions, but the polymer coatings of outer coverings are not as permeable in the cold as they are at room temperature, while the coatings of some vapour barriers become more permeable when subjected to the warmth and high humidity in a well insulated sleeping bag. One strategy that has proven successful with highly motivated individuals is to never let the sleeping bag get warm enough to melt the frost that has formed in its outer layers. This means that all people in the tent must get out of their bags, pack them and put them outside before lighting any stoves, which might be impractical in a military setting. It might be possible to construct the bag and/or the insulating layer so that frost can be physically removed, or so that it causes no problems if it melts…

…Water can also get into sleeping bags directly from the humidity in the air of a heated tent, even though the relative humidity of the air may be quite low (Osczevski 1979). If an unoccupied sleeping bag is left lying on the tent floor, the insulation in its lower regions will rapidly cool to a temperature between that of the tent and the cold ground or snow on which it lies. Unless there is a vapour barrier between the insulation of the sleeping bag and the warm, humid air of the tent, water vapour will diffuse into the insulation in the direction of the temperature gradient from warm to cold and condense or form frost in the colder filling material.”

Again, not so simple.  When most people think of a VBL, they think of things like silnylon or PU treated clothes or sleeves, or maybe a plastic sheet sleeve, etc.   But in order to avoid the above,  you not only have to have an internal VBL, but the insulation in general needs to be well sealed in a VBL–which is not as easy to do.

Layered thin CC foam + air spaces + a space blanket or two + fabric sleeve that can be opened, would be one way to more effectively deal with this vs using traditional fibrous type insulation.  If you do it right, you could also get a pretty decent warmth per weight ratio.

I’ve already been looking into it, and found that one can get 1/8″ (3.2mm) Volara foam for pretty decent price.

Question: Assuming one were to use true VBL (not of which were discussed in the article – are there true VBL at low temps?) between both sources of moisture, being the body and the outside of the insulation, what would the effect be on the ability to actually heat up the insulation?

Justin

that article is 15 years old

ask yourself how modern folks survive im those conditions these days

i posted up the blog of one, he uses an overbag

vbls AND overbags are proven in those temps

again read skurkas VbL article on bpl, its quite good

im happy your trying new ideas … I look forward to yr tests at those temps

;)

As Eric wrote: VBLs and overbags. In fact, VBLs by themselves are close to enough, but you MUST breath outside your bag!!!

Justin quoted another article which said that if your ‘VBL’ is not really a barrier to water vapour, then you may have problems – in which case I would have to ask just what are you doing in your selection of gear? That sounds more like incompetence than anything else to me. Some well-known Antarctic explorers have been remarkably poor at this sort of planning. Tough, sure, but logistics?

If you are planning to use a VBL for long periods, then you need to make sure the material you are using really is a 100% barrier. Something like GTX would NOT work. Strong bubble wrap, surprisingly, would work, probably quite well.

Encapulating all the down in a true VBL might not work all that well: how do you get the air out to pack the down gear away? Valve maybe? On the other hand, absorption of moisture from the air (rather than from your breath) when you reinflate your down is unlikely as the humidity content of air at -20 C is kinda LOW. Hum … pillow pump maybe?

Safe travel under Antarctic conditions is TECHNICAL, and Darwin is always waiting.

Cheers

Eric, i did read Skurka’s articles on VBL’s.  Skurka had some more extreme cold experiences with “With temperatures as low as -20 F”, but he did not and has not done a true, Arctic or Antarctic, long term experience like the people referenced in the article that Daryl shared.  Places where the more extreme low is not just -20 sometimes, but regular day to day temps below -30 and below.

It’s another ball game.

And in 15 years, not much as changed as far as insulation goes. Climashield is revamped Polarguard and down is still down.

Sure, some WPB’s are a little more “breathable” now, but there hasn’t been any huge leaps of evolution in that area.

“Justin quoted another article which said that if your ‘VBL’ is not really a barrier to water vapour, then you may have problems – in which case I would have to ask just what are you doing in your selection of gear?”

Well first, i did not quote “another article”, i quoted the one that Daryl shared in his OP.  2nd, it seems more nuanced than that.  Essentially the writer seemed to be saying that some highly moisture impermeable fabrics used, can become more vapor permeable under certain conditions.  In other words, it’s not a static, one size fits all conditions.

Some people use silnylon as a VBL for example.  In some conditions it may work ok, but in others, it may not.  After all, a lot of silnylon isn’t even highly waterproof to begin with, let alone a great vapor barrier. It’s much easier to block water droplets than air laden with moisture trying to diffuse from a higher temp/humidity to lower temp and humidity gradient.

“That sounds more like incompetence than anything else to me. Some well-known Antarctic explorers have been remarkably poor at this sort of planning. Tough, sure, but logistics?”

Probably is the case, i don’t know enough about the people in the article or Antarctic explorers in general to make a generalization though.

“If you are planning to use a VBL for long periods, then you need to make sure the material you are using really is a 100% barrier. Something like GTX would NOT work. Strong bubble wrap, surprisingly, would work, probably quite well.”

I’m pretty sure that the article wasn’t addressing people using known WPB fabrics as a VBL (you would have to be pretty daft to do or think that, i think), but fabrics considered generally more highly impermeable.  But yes, bubble wrap would probably work well as a VBL because it’s mult-layered and with a cushion of trapped air in between the individually highly (but probably not completely) impermeable layers.

From my limited understanding so far, i’ve learned that it’s surprisingly hard to get a true and complete  barrier to vapor, especially when considering common, single layer materials or coated fabrics.  When you add high humidity vs very low humidity and large temperature differential, i suspect, like the article is trying to say (i think), many highly to moderately impermeable fabrics and materials tend to become more diffusive.  Like their pores tend to open up more under such conditions.

Multi layers will naturally tend to work better though in general.  At the very least, it should significantly slow down the diffusion process to insignificant or at least manageable levels.

“On the other hand, absorption of moisture from the air (rather than from your breath) when you reinflate your down is unlikely as the humidity content of air at -20 C is kinda LOW.”

And if you note the quote i quoted earlier, they made the point that while the outside air is quite dry at those temps, the air inside a tent can become much more humid and from various sources–body(s), cooking, fuel combustion, etc    To some extent, it depends on how well one’s tent is ventilated, but it seems that Arctic type tents are usually more sealed up, because of the common problem with very high winds, verse the typical tents that a lot of say BPL members use.

So theoretically, it may be 10% or lower humidity outside of the tent, but could be as high as 60% or more within the tent, especially if there is a storm going on and everything is sealed up to deal with that.

Personally, if i ever do a true Arctic or Antarctic type, long term trip, with low’s regularly at or below -30*F, i think i would not rely on Down or even synthetic fiber insulation for my sleep insulation.  With a pulk, it seems that foam combo’s would be a lot more forgiving of such extreme conditions and potential mistakes.

It doesn’t seem like too many of us here are true Arctic/Antarctic type explorers, so to some extent, we’re all speaking more theoretically and from hearing/reading what other’s have experienced.  I’ve experienced -20* F briefly, but something tells me that even -35* F is another ball game, especially when done day in and day out for a long period (near month or month+).  I think that anyone who has experienced that and lived through it, should be given some kudos, even if they did make some mistakes or didn’t have a very accurate understanding of all the factors.

Justin …

this gentleman has a total of 6 months (nightly count) in sub -40C conditions in the canadian arctic including -60C nights

what does he suggest? …. Vbl and overbags

in fact he uses a warmlite bag that has vbl built in

his blog is worth reading for the sheer amount of real and practical experience in the arctic … He pulls no punches on gear

http://kobalenko.com/gear.htm

Thats actual decades of experience …. Not BPL theorizing

his information is current as of 2015 … Not 15 years old

;)

Thanks for the link Eric.  I’m sure those help quite a bit, but after all, i was not “BPL theorizing”, but addressing what an article that addressed a general overview of Arctic type experiences and the problems encountered.

Again, i fail to see what 15 years difference has changed all that, so drastically.  Ok, we got more surface hydrophobic and perhaps slightly higher quality Down, and WPB’s are a little more breathable, but please explain to me in some actual detail and real world examples, what is SO different regarding these basic, core factors?  After all, the whole article was primarily about moisture accumulating in Down or synthetic insulation,  and even with VBL’s being used.

Overbags is not a brand “new” idea, it’s a concept that’s been around for awhile.  You’re telling me that none of the folks referenced in the article knew about overbags?

I liked the article because it challenged some of my assumptions, which were based on overly simplistic understanding.  It made the whole thing more complex, relative, and nuanced for me.  As i earlier said, i said and thought similar as you said at first.  I ended up editing my first response after i read the article.

There wasn’t ever a doubt in my mind of VBL’s and overbags helping after reading the article, but rather that it’s not necessarily a complete fix that eliminates all moisture accumulation over time. It’s nice to understand how moisture can accumulate in a bag some, just from the higher humidity in a more sealed up tent.

So, i’m not really disagreeing with you in any core way, i just have come to see it’s a little more complex, relative and nuanced, thanks to the overview of that article which is based on various people’s long term experiences in those extreme conditions.

Everyone here is either “BPL theorizing” or “BPL regurgitating”

at least till the great skurka decides to comment

thats all there is to it

;)

Solutions:

1. VBL liner sack (VBL must be removed, aired and frost beaten off daily.)
2. Psolar face breath-warming mask (reduces respiratory water loss at night)
3. Peruvian knit hat tied under chin or heavy balaclava W. neck coverage

Nos. 2 & 3 permit sleeping with only your face exposed and ALWAYS outside the hood.

The Scott South Pole expedition bags were so frost saturated they had to be carried flat on their sledges. Amundsen’s people used fur sleeping robes and XC skis. Guess whose expedition had 100% fatality?