Sleeping bag condensation w/ Pictures

[Travis Leanna]

What you see below is the kind of moisture I produce in ONE night.

Temps in the low 20's, upper teens. Sleeping in a Trailstar with an open door. Using a Marmot Pinnacle 15*F bag. Snow on the ground.

When I sit up, the moisture is pushed through the shell, which is what you see in the pictures. This happens every time I sleep in winter with various shelters and conditions. I'm not a sweaty guy. I was able to weigh the bag damp and dry, and I found at least 3 ounces of water in the bag. This is very frustrating, and I've resigned myself to using some type of VBL on any trip longer than one night.

Any thoughts?

[James holden]

where exactly was the moisture … and how warm did you feel in the bag?

what were you wearing inside the bag?

[Travis Leanna]

The pictures were from around my waist/stomach area, though the entire bag was dampish.

I was using the bag as a quilt, and felt adequately warm going to bed. I always get chilly as morning approaches, possibly due to loss of loft.

I was wearing a thin wool base layer and R1 zip up on top, and powerstretch tights and thin nylon pants on the bottom.

(My 3,000th post. Woohoo.)

[Jerry Adams]

I get chilly as morning approaches

I always assumed it's because it gets progressively colder until just before sunrise, and my metabolism gradually slows down as the night progresses

3 ounces of extra wheight, interesting. Okay, I'm going to have to bring my scale with me now. I just weighed it – 3.5 ounces. That's a trick – how to you get the scale to weigh itself : )

[Travis Leanna]

Jerry,
Colder as morning approaches and metabolism are probably important factors, but its hard for me to ignore the wet down.

[David Olsen]

UNCLASSIFIED
Defense Technical Information Center
Compilation Part Notice
ADP012412

http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADP012412

[Travis Leanna]

Thanks David,

I can't read it now, but I'll definitely get through it at some point.

[James holden]

you did nothing wrong so far as i can tell

the likely scenario in my mind is that you went to bed a tad warm, maybe sweated a bit, and as temps drop that moisture condensed into yr bag …

which is why experienced people dry their bags in the wind and sun every morning or chance they get …

synth of course will have the same issue … but then it dries faster and still insulated when a tad damp …

and its why some people use synth overbags ….

just remember that condensation will tend to end up in the last layer … and if yr using down one should know how to deal with it should it get damp (not just the usual ill stuff it in a dry bag and itll never get damp/wet yadda yadda yadda)

and why some very experienced people in some recent threads use synth …

[Travis Leanna]

Thanks Eric. Yes, I agree that knowing the limitations and proper use/care of each piece of gear, especially critical ones like a sleeping bag, is crucial.

I've experimented with MYOG VBL's a few times, and though they get clammy, my insulation stays dry and I'm warm. I think I'm going to get a silnylon rain suit next winter. Relatively light and will keep my insulation dry. Cuben would be nice for the weight, but I'm not plopping down the $$ for a cuben VBL that I'll only use a handful of times each year.

My wife usually comes backpacking with me, and in the exact same conditions, her bag is never damp. The only difference is her and her bag, which is a Montbell SS #1.

[James holden]

3 cheap alternatives

– large garbage bag
– amk 4 oz bivy that you can use on emergencies on summer daytrips as well
– those boxing sweat suits you can buy at wallymart

[rOg w]

deleted

[Randy Martin]

First off I am unclear from your description whether the moisture is on the outside or inside of your bag. Either way it seems a Bivy should be used. I am wondering if using a Bivy would help move the condensation point to the outside of your bag if the issue is moisture on the inside. I assume the outer material of your bag is more resistant to moisture absorption than the inner material and therefore wouldn't absorb moisture that was created between a bivy and the bag.

The other thought is your exhaled breath. Are you making good use of a tightly cinched draft collar to seal out your exhaled breath from going into your bag?

[Lance M]

Travis, I vaguely recall from years ago similar moisture but to a lessor degree. I didn't give it much thought at the time, assuming it was from outside humidity.

I have experienced dew recently which reinforced the importance of site selection. Here's a few pictures.

Cowboy camping site:

Morning dew:

Morning dew, close-up:

I was able to shake off quite a bit and then dried it in the sun during lunch break.
The DWR Momentum 90 from Thru-hiker worked pretty good.

[Matthew Zion]

If you're sleeping on snow or grass you'll have morning condensation every time — just comes with the territory. Thats why taking time to dry the bag out later, if you're out for multiple days, is so important.

[Dondo .]

Travis, same thing happens to me in similar temperatures whether my bag is down or synthetic. If the sun never comes out, synthetic can buy you a couple of days. Years ago, I used a vbl bag but quit doing so because I got all tangled in it. Like you, I'm considering adding some kind of vbl shirt and pants for colder conditions.

[EndoftheTrail]

I can't help but wonder why you slept in the teens or twenty's with the tent door open? I wonder, had you slept with the door closed and minimal (but adequate) upper venting, then the coldest spot will be the walls of your tent — and not the outside of your bag??

But I also agree with the other posts — if conditions are "right" — and you camp for multiple days without any sun to air out your bag, then it will keep accumulating moisture…

[Paul McLaughlin]

Totally normal. At those temps the dew point is inside the insulation – unless maybe at super-low humidity. An enclosed tent might help, since the interior of the tent will be maybe 5 degrees warmer than the exterior air, and that 5 degrees might be enough to get the dew point outside the bag. That's what my bag always looks like in the mornings when I'm snow camping in the spring at those temps. If I couldn't count on fairly sunny days, I'd be thinking VBL myself. But the usual sierra spring is pretty sunny, so it works out for me to just dry the bag every morning.

[Travis Leanna]

Hmmmmm, thanks for everyone's thoughts.

I was always curious as to 1.) if I was doing anything to exacerbate the problem; 2.) if my moisture output was abnormal; and 3.) if anyone else had this issue. Seems like it just goes with the territory for some people.

I am a bit curious to know if the bag shell material is trapping more moisture than usual. Marmot uses 100% Nylon Silicone DWR 1.05 oz/yd.

[Paul McLaughlin]

At those temperatures the breathability isn't the big factor, but it can be at warmer temps, when the dewpoint is outside the bag. and a more breathable fabric will allow the bag to dry faster in the sun. But how you can determine the actual breathability of that fabric and compare it to other makers is a whole 'nother question.

[Ken Thompson]

bed wetter ;)

[Travis Leanna]

>bed wetter ;)

LOL! :)

The first time I ever noticed it I was drinking some water. I thought for sure I had spilled on myself!

Although, this bag may be history. I just got my enLIGHTened Equipment 20*F quilt with overfill today. It appears to loft better than the 15*F bag in this thread, it is around 20 ounces lighter, and could be much more versatile.

When I first laid out the quilt I noticed the large gaps between baffles (Tim uses Karo baffles) and I was a bit worried that down shift would be an issue. However, from everything I've read, Karo baffles do a fine job of keeping down in place, unless you *want* to shift it around.

It seems really easy to move the down around, which means I can potentially use this quilt year-round. Shift all the down to the sides for warmer nights, and shift it back on top of me for the colder ones. I'm really excited to use this and put my theories to the test.

If this quilt can reliably take me to 15*, which it very well may with the overfill and if I wear my insulating layers, then the bag in this thread will probably go up on gear swap. If the Karo baffles allow me to shift enough down to make this quilt usable in the other 3 seasons, it may very well replace my Montbell #3 also. Time will tell.

I just hope I can contain my excitement and not wet the bed…

[Inaki Diaz de Etura]

> At those temps the dew point is inside the insulation – unless maybe at super-low humidity

Indeed, I think the ambient humidity still plays a role here, even at those temps.

Just a couple weeks ago I was sleeping in conditions similar to what the OP described: upper teens, in the snow. The bag (a Nunatak Arc Expedition) was warmer graded, might be some thicker. Everything inside a non-waterproof topped bivy set up by the side of a stunted pine tree. The key difference was a steady, dry breeze that was blowing all night. Everything was dry, very dry, in the environment and in my sleep system. I don't know if there was humidity condensed inside the bag (didn't weight it) but surely none that I could feel to the touch, even when packing.

[Hiking Malto]

Is there any chance that you are going to bed too warm? I found that condensation in my bivy was greatly reduced if I go to bed lightly dressed and add a layer or items later in the night when it gets colder. I believe what may have been happening is I may have been sweating early because my total system was too warm for the conditions at the time.

[David Goodyear]

That effect is pretty normal. We actually use the furnace of metabolism to dry out articles of clothing and sleep in our boot liners to dry them out on multi-day winter hikes. We push the moisture through the bag – I can't see sleeping in a vbl, but that is just me. I like to wake up warm and fully dressed – hunkered down in my sleeping bag while cooking a hot breakfast. The trick is to get the dew point outside your main sleeping bag. Most of the time we will wake to a frost lining on the inside of the bivy sack and just turn it inside out and shake. Sometimes there are ice balls inside the sleeping bag insulation. A little morning sun helps also. Some arctic travelers use a sacrificial overbag that captures the moisture and saves the main bag. This bag is replaced when they get their re-supplies.

I thought there was a discussion of this a while back in a thread about layering sleeping bags, but finding it may be a chore.

Enjoy,

Dave

P.S. I should mention that I use synthetic insulation – I haven't gone "down" that road yet.

[David Olsen]

It appeared to me on reading the military experiments that they describe the down bags
as retaining less condensation than the synthetic bags.

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