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?

Edited by T.L. on 03/05/2012 10:53:54 MST.

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

what were you wearing inside the bag?

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.)

Edited by T.L. on 03/06/2012 10:33:33 MST.

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 : )

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

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Thanks David,

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

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 ...

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.

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

deleted

Edited by rOg_w on 05/28/2012 17:37:17 MDT.

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?

Edited by randalmartin on 03/05/2012 12:49:25 MST.

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.

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.

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.

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...

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.

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.

Edited by T.L. on 03/05/2012 22:13:20 MST.

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.

bed wetter ;)