Thinking about converting to down, but have questions

I switched to down without problem.  I do 6 night trips down to 20 F.

I weigh my bag after a trip and there’s little increase in weight so little dampness.

I think the problem is at lower temps and longer trips.  Based on comments by people here.  warmlite.com has some good info.

Your body sweats.  The water vapor goes through bag and out.

The temperature inside the bag goes about uniformly from body temp inside to ambient temp outside.  At the point in the bag where the temperature goes to freezing, any water vapor moving out will freeze and stay at that point.  If that freezing point is outside the bag, then all is well, water won’t accumulate in the bag.

There is a skin of air on the outside of the bag that gives about 10 degree F of insulation, so as long as the air temperature is 22 F or higher, the freezing point will be outside of the bag so all is well.

That’s all approximate.  The further below 22 F it is, the worse it is.  I haven’t found 20 F to be a problem.

There are two solutions.

The warmlite solution is to have a vapor barrier liner so water vapor isn’t flowing through the bag.  You could wear vapor barrier clothing.

The other is to have a cover on the outside, for example synthetic.  Warm enough that the freezing point is inside that cover rather than your bag.  That will keep your bag dry.  If the cover is synthetic, it will still maintain a lot of warmth even though it gets damp.

You could try the down solution, weigh it after trips, if bag gets damp then try one of those solutions.

Thanks for the detailed info. That was exactly what I was looking for.

Maybe a 30F down quilt and a synthetic over-quilt.  I had a thread about this a while ago:  https://backpackinglight.com/forums/topic/synthetic-overquilt/.  I know Jerry replied to that thread as well – thanks!

Two other resources:

Ryan has talked about this multiple times, maybe it was youtube or a podcast, because I can’t find it with a simple search  Someone here may have it handy.

Enlightened Equipment has a webpage “How to layer quilts for sub-zero camping”:  https://support.enlightenedequipment.com/hc/en-us/articles/115002770588-How-to-layer-quilts-for-sub-zero-camping

I try to avoid winter camping, but sometimes when I go to Yellowstone in September it is winter-like.  No exception this past fall, when temps in early Sept. were just above or at freezing, then winter happened and night-time temps routinely dipped below freezing.  Two years ago temps dipped into the low 20’s.  My bag for these conditions for the past few years has been a Marmot Xenon W’s, comfort rated to 20 degrees F and insulated with 850-fill goose down.  I think my bag (purchased in 2013) predated the use of polymer treatment of the down.  Often this time of year the weather is a mix of sun-wind-rain-sleet-snow, and I am by myself in a 2-person, 4 season tent sleeping on an Exped Downmat and wearing wool socks, merino base layers, and a hat.

In the conditions I have described, I have never been cold in the tent in the bag for as long as 10-12 nights of use.  Even when a previous tent was on its last legs and actually leaking 3 years ago, the bag got some moisture on the exterior but never “wetted out” or became uncomfortable to sleep in.  I do tend to bury my face in the hood at night and notice the bag is a bit damp in the morning from breathing, but even a little weak sun warming the tent seems to be enough to dry things out.

This long-winded description is trying to tell you that in the dry western climates that you are describing, you should be just fine in a down bag.

“I try to avoid winter camping”

Funny, I avoid summer camping :)

I feel fairly confident in saying that, regardless of temperature, the SE US is a humid place compared to most…maybe the PNW wins.  I’ve exclusively used down bags (WM Megalight) and quilts (EE Enigma and Revolution) for the past 10 years with no problems, I’ve being toasty warm and completely happy with my equipment choice.  You must pack your down gear to insure it stays dry in your pack, and if/when it does get damp, find 30-45 min. each day to lay it out in the sun.  I recommend at least one black side to facilitate this.

same here, I tend to avoid summer camping, much prefer winter, in the PNW

a lot of good ideas from people on this site.  Many previous threads about this subject.

I love EE down bags.  The one problem I experience in the SW (Colorado,  mainly) is condensation on top of the bag.  Little droplets everywhere.  I always try to shake them off or dab them dry, but inevitably, the nylon gets a little damp and then gets shoved into the bottom of my pack for the day.  It’s a little concerning with a down bag, and I’ve never found away to avoid it.  Others have complained about similar issues with EE bags.  Not a deal-breaker for me, but certainly something to consider.

Maybe the surface of some fabric accumulates condensation more

Provides sites for water molecules to condense onto

Sort of like in the atmosphere, if you have dust particles, the humidity in the air can condense on them and form clouds

You might want to have a look at Nunatak’s down/apex hybrid quilt:

https://nunatakusa.com/home/175-nebula-hybrid-quilt.html

I haven’t tried it yet, but need to add another adult-size quilt to the family quiver (son just surpassed me in height) and have that on my wishlist.

But we’re in the PNW. If I were in the southwest I wouldn’t care as much about hedging my bets with synthetics.

Condensation is mostly an issue with the relative humidity and temperature in the environment you are sleeping in more than anything else. When it’s cold, this issue is not about preventing condensation, but managing it.

Down is significantly more permeable than synthetic insulation, so it’s important to remember that a down quilt is not “the cause” of this.  However, EE bag users definitely have expressed that their quilts seem to “collect” more condensation than what they used before. This might be due to the cold outer surface combined with a rather permeable and water resistant shell.

Personally, I use a silk mummy liner as a lightweight “overbag” on top of my down quilt, which significantly reduces any potential of condensation since it quickly gets wicked away when it forms.

For me, condensation is more concerning in humid environments.  Sleeping in New Mexico and southern Utah is a perfect application for down. I use down in the humid southeast too.  If was was normally sleeping at 20, I would probably get a 10 degree quilt for a little factor of safety.

You can get a little condensation, especially if cowboy camping.  If it’s concerning, camp under a tent, tarp, or cover.

I won’t do any winter backpacking without my down items—sleeping bag, down parka/pants, down mittens.  And I live in the mountains of TN/NC where typical winter storms are 60 hour rainstorms at 35F, so humidity is high.

Here’s what happens:  You leave the house for a 21 day winter backpacking trip and your nice down bag is fully lofted and dry as a bone due to home storage.

After 3 or 4 days in cold temps with high humidity your down bag has lost some loft due to in-tent condensation and ambient moist air.  No big deal.

By Day 5 you’re in dry conditions with minimal humidity and some wind and your bag lofts back up to almost home-like dryness.

On Day 8-12 you’re caught in a winter rainstorm/sleetstorm and/or blizzard and the bag shell gets moist and stays moist for the duration.  Some loft is lost.

By Day 18 dry air returns and the bag lofts back up etc etc.  The tent and the bag etc gets bone dry again.

Btw, you can always tell how “moist” your bag is, (or how dry) by stuffing it in its stuff sack.  At home it’s hard to get the bag inside its stuff sack because it’s so dry (I use a 35 liter sea to summit eVent sack).  My -15F rated bag barely fits.  On wet days during the trip the bag squishes down much smaller in the stuff sack—cuz it’s a little moist.

Point is, a goose down bag works great on backpacking trips.  Don’t get it intentionally wet and remember, a 4 day rainstorm will eventually end with 3 or 4 days of cold and dry.

Kept to synthetics for many years due to fear of down baqs getting wet and useless, as had occurred a few times.  Then Montbell came out with their patented spiral wrap down bags, and a detailed review on BPL persuaded me to switch.  The review mentioned the awesome water repellence of the shells, and 10 oz less weight than the lightest synthetic I’d found.  Think the review was by Will Rietveld, but not sure.

Got the 30F model (20 oz), and with an option to wear top and bottom puffies (.5 lb each) from BPL that doubled as camp wear when needed, have always slept warm down to 20F, unlike before, when I shivered often.  Also never feel constricted.   One caveat:  the bag was filled just enough to hold its shape without cold spots, but was not over stuffed with down.  So it never gets compacted except when in the pack during hiking.  Make my own stuff sacks that are waterproof; but if using any other, would put a polyethylene bag inside the stuff sack and seal it to keep out moisture.

Your choice of a 20F bag sounds about right, considering your temps and shelter choice, which should keep condensation off the bag.  However, can’t vouch for EE or any others you may be considering.  Did research a few very light Western Mountaineering models for a friend, and she was very satisfied with one of those – but note she was sleeping in trail hostels on the treks she used it for.

@garrett: yeah tipi’s got it, I think. At the freezing limit, down works much better than synthetics, providing you can keep vapor from condensing within the bag. You must consider the goal of “pushinf” the moisture barrier to the outside of the outer shell. This can be accomplished through increased baselayer insulation or a synthetic overbag; just make sure your emissive moisture does not stay in the down. Rock on.

You might want to have a look at Nunatak’s down/apex hybrid quilt:

https://nunatakusa.com/home/175-nebula-hybrid-quilt.html

That looks like a great idea, but boy, it’s over 500 once I spec it out.

Lots of good information. Question though… At what temperature do people use two bags? Anything under 20F or is condensation minimal at that temperature. Im thinking about buying a 25F down quilt and a 50F synthetic quilt as the outer bag. I would prefer just to bring a conservative 20F down bag only, but that would just depend on how bad condensation is with down around 15F-20F.

If I’m expecting 15F—I’ll take a 0F rated (or subzero rated) down bag.  A high quality stand-alone sleeping bag is all you need for winter trips—it is lighter and less bulky than a two-bag system.

But there’s nothing wrong with carrying two (or even three) sleeping bags—it’s all we ever did back in the old days when we were dirt poor.  It’s called Dirtbagging.

Lots of interesting stuff in this thread!

But the first thing that occurred to me (and I admit to not having read each of the OPs posts in great detail) is: WHY are you considering the switch from synthetic to down? What problem are you trying to solve?

Is something lacking in your current sleeping bag/quilt?

20F synthetic bag just takes up too much space in my ULA Circuit. The weight difference isn’t an issue for me (to an extent). That said, if I stick with synthetic, then I would have to move to an even larger backpack, which would add even more weight and bulk.

You might want to have a look at Nunatak’s down/apex hybrid quilt:

https://nunatakusa.com/home/175-nebula-hybrid-quilt.html

That looks like a great idea, but boy, it’s over 500 once I spec it out.

Yeah, that’s why I don’t have any real life experience to share on that yet! It’s a premium brand, on par with Katabatic. Worth it….if one can afford to spend that much on gear.