Damp and down

[BillyBob58]

For a detailed (and somewhat technical) explanation, look at this discussion from another forum:
http://bushwalk.com/forum/viewtopic.php?f=15&t=28061

I read that. Wanted to comment: vapor barrier clothing and a frost bib, guys! (there is some discussion of VBs finally) I suspect that would result in a dry bag, and much drier inner tent surfaces. Works for me. Of course, if outer moisture from the air(fog/mist/rain) is managing to get past your tarp/tent/bag shell, a VB won't stop that. But, at least they wouldn't add a ton of body vapor/sweat trying to get out past the cold outer bag shell into the vapor loaded high humidity air, likely 1st condensing inside the bag/quilt shell. That certainly can add a lot of moisture to the interior of a bag.

Interestingly, the guy with the damp bag problem was using treated down. So that is not encouraging.

Also, they discuss the foot area of bags getting damp 1st, and they are wondering why. I just got done telling about the time the foot area of my HHSS and synthetic sleeping bag got soaked from condensation. The guys over at BPL have more than once discussed how the foot boxes of their down bags were usually the first thing to lose loft. I think the reason might be simply that the feet put out more vapor than other parts of the body. A problem I long ago solved with VB socks.

[HandyRandy]

But last day of the trip, he said he was glad we were headed out, because his untreated down had obviously lost significant loft.

Interestingly, the guy with the damp bag problem was using treated down. So that is not encouraging.

Is this discrepancy a typo?

[BillyBob58]

Is this discrepancy a typo?

Do you mean the discrepancy that he was using treated down and was also had problems with damp down? Not a typo by me, but possible it could be a typo by the guy iwho started the thread about the damp bag. I guess one of us would need to join to ask him.
http://bushwalk.com/forum/viewtopic.php?f=15&t=28061

..............I don't think my wet sleeping bag is anything to do with sweating; on the whole I have to layer like mad to stay warm in bags that would make most people cook. I'm a hopelessly cold sleeper. To illustrate - on the AAWT in Nov/Dec a few years back I used a Mont Franklin with a minimum COMFORT temperature of -12'C (850gram fill of 700+ loft goose down), and that was just right with thermals top and bottom, merino socks, beanie, down jacket and if it approached anything close to/below 0'C I just added my rain jacket and pants which act as like a VPL and was nicely cosy. This walk I took a hoodless sleeping bag that Undercling Mike customed for me which has 600g of 950 fill HyperDRY goose down and taller baffles to match and providing I layered to a similar degree as in the past and used the separate hood combined with a beanie I was fine warmth wise down to as low as 0'C.

But I was starting to feel the cold in the early morning hours as my bag got more damp/wet and lost loft and it was getting more and more difficult to find the time in the short winter days as well as suitable weather (sun and wind) to dry my bag properly every day.............

[HandyRandy]

Do you mean the discrepancy that he was using treated down and was also had problems with damp down?

No, my mistake. I didn’t read that linked article and thought you were referring back to your friend again in the second post. Regarding treated down though, UGQ has chosen to revert back to untreated down and I haven’t ever noticed anybody complaining about that here. Here’s their comment on their website about the matter:

“UltimaDOWN is not a hydrophobic treated down. Although we have offered hydrophobic treated down in the past, we have weighed the benefits vs. drawbacks carefully, and have recently stopped offering WR down. The benefits, which are marginal at best in real world scenarios, are offset by lower loft, intra laundering clumping, and the need for more down to offset the lower lofting and possible clumping. Effective April 11, 2016, we will no longer use hydrophobic down in our products.”

[BillyBob58]

No, my mistake. I didn’t read that linked article and thought you were referring back to your friend again in the second post. Regarding treated down though, UGQ has chosen to revert back to untreated down and I haven’t ever noticed anybody complaining about that here. Here’s their comment on their website about the matter:

“UltimaDOWN is not a hydrophobic treated down. Although we have offered hydrophobic treated down in the past, we have weighed the benefits vs. drawbacks carefully, and have recently stopped offering WR down. The benefits, which are marginal at best in real world scenarios, are offset by lower loft, intra laundering clumping, and the need for more down to offset the lower lofting and possible clumping. Effective April 11, 2016, we will no longer use hydrophobic down in our products.”

Wow! I had read something about that, maybe from them, in the past, but had forgotten about it. And I sure do hate to hear it. Because I had purchased a JRB TQ with treated down couple of years ago(so far everything seems fine with it). And my plan always was to at some point replace my regular down UQs with treated down. In fact I sold my regular down MW4 a while back(and before that my Pea Pod), since I had planned on at some point getting treated down.

But maybe I need to rethink that? Maybe if I am going on a remote trip where moisture control is a major concern, and just going home or to a trail town is not an option, I should stick with Climashield and Primaloft, as I always have? Or, at least down quilts rate significantly lower than I expect to be, to help make up for any lost loft? Or what I often do: a combination of down and synthetics?

Who is it that used to have the treated down in a jar of water, shaken up periodically, and over some long period of time it still had not collapsed, unlike the regular down which collapsed pretty quickly? Was that UGQ, or someone else? Whoever it was, that certainly seemed a bit more than a marginal benefit, though it says nothing about the downsides he mentions.

Plus, I remember a wet sleeping bag test by someone(who? Some magazine or web site) They put a few different brands of bags of various insulation types and shells, to the test after soaking, then slept in the cold(maybe in a freezer?). They would stay in the bags until they either were too cold to stand it, or were warm enough, whichever came 1st, I think. I was really surprised to see that not only did the synthetic bags absorb much more water(by weight) than the treated down, but the down also dried quicker(in my experience, my Polarguard jacket has always been very quick drying when first soaked and then worn on a cold weather hike for testing). However, despite those two apparent huge advantages for the treated down, the testers were able to go from freezing to warm enough much quicker in the synthetic bags. Even though those bags were still wetter at the point of becoming warm. That was a big surprise to me. Wish I knew where that test was.

[Brooklyn]

Down losing loft due to moisture, actual liquid or humidity or fog or whatever, treated down or untreated, is just the nature of down. It's not a "well, this could happen. or I've heard of it." It is just the nature of the beast. If you're worried about it, synthetic is the way to go. Also, it's worth nothing that even wet down has insulating properties, but obviously not as much and synthetic insulation which, like wool, is still very effective at warmth retention even quite wet.

[BillyBob58]

Eureka! An answer to the mystery has finally occurred to me, the mystery of how it is some people report being warmer without clothing(anti layering approach) while in a quilt. at last I can think of an answer that has some laws of physics behind it!

We have been discussing where the dew point occurs inside a quilt. Assuming that a quilt is thick enough to keep me warm at 20F without the help of any clothing or other layers, then adding layers will tend to move the dew point closer to your skin. By keeping my body warmth closer to my skin, slowing it's escape into the down.

Removing layers, by allowing more body heat to escape into the own, will tend to warm up more down in the quilt(as "sllep naked or almost" proponents have always said), down that is further away from your skin, possibly even moving the dew point just outside the shell. If so, even though you have lost some body heat to heat up more of this down, some or all condensation of body vapor into liquid might now occur outside of the shell. Which will leave the down loftier for longer.

Adding layers will move the dew point closer to the skin, and possibly inside the shell.(and of course possibly even cause overheating and sweat to be wicked into the down) So you get in and head off to sleep, and your vapor fights it's way through your clothing which, by keeping you from losing as much body heat into the down, causes the down to be colder. This should be a good thing on it's own, as it means you have not lost body heat in order to warm up that down, that heat has stayed closer to your body's core where you need it. However, colder down might well mean a dew point inside the down. So as your body vapor fights it's way out through your breathable, non VB clothing, it finally contacts that dew point and condenses to liquid water, inside the down. Loft is lowered. As the temps continue to drop, the dew point gets ever closer to your skin. Loft is lost, and you are now cold. Removing layers might even allow the down to warm up enough to move the dew point back outside the down, and body heat might be able to dry the down, and loft will increase and you are warm again. Makes total sense.

But as one who has successfully layered for many years, as one who does not sleep colder when I wear my clothing and who count on it as part of my sleep system, and most of all as one who has incorporated VB clothing in recent years with huge success( toasty, with feet over heating and sweating, at 6F in an HHSS and a 30F TQ for ex) none of the above has ever applied to me and it was hard for me to comprehend. It seemed to defy the laws of physics, but I had not considered the dew point inside the quilt's shell, at least not how that place might be changed by layering.

But then again, if I was layering, it usually meant I knew my quilts were not warm enough to keep me warm in the expected temps. And with VBs, it is irrelevant where the dew point is. I am willing to bet $10 that, if using a VB at skin level, if a person adds more clothing to any bag in any temp, that person is going to get warmer- even over heating, all night long. The more clothing added, the hotter that person is going to become. Maybe someone will put that to the test next winter? No need for me to do so, as I am already one of those people who get warmer by adding layers, with or without a VB. But at least now I can see a reason why, under the right conditions, I might warm up by removing layers, or get colder adding them. Assuming of course, no VBs are used and the quilt is warm enough to not need added layers.

Also, If the bag is NOT warm enough to keep you warm at 20F with NO layers, that quite possibly means the dew point is already inside the shell, in the down. If so, adding layers will not worsen the situation with the dew point, and probably will add much needed insulation. Of course, adding a VB wipes out any and all concerns about the dew point and the condensation of body vapor.

[BillyBob58]

Down losing loft due to moisture, actual liquid or humidity or fog or whatever, treated down or untreated, is just the nature of down. It's not a "well, this could happen. or I've heard of it." It is just the nature of the beast. If you're worried about it, synthetic is the way to go. Also, it's worth nothing that even wet down has insulating properties, but obviously not as much and synthetic insulation which, like wool, is still very effective at warmth retention even quite wet.

I agree.

[BillyBob58]

Since the subject of this thread seems to be concerned with bags getting damp not from rain, but from either fog/mist or internal moisture condensing or both, I though I should mention a trick I have heard of recently from some guys who are vastly experienced at remote back country travel. And these guys love down but have concerns about loss of loft from moisture for the same reasons mentioned in this thread. They have had it happen. They have no trouble keeping rain off their gear, but mist and fog and internal condensation of body vapor or sweat and having to pack up every morning, can be a real bear for them to deal with. One of these folks(Andrew Skurka) has become a major advocate of solving a lot of these problems using VB clothing(like me), but most have not.

But even a VB leaves the question: If condensation of of body vapor(and/or absorption of sweat) is controlled from the inside(VBs inside the quilt/bag), how readily can a fog, that gets under a tarp or inside a tent, pass through the outer DWR shell of a quilt, and make it into the insulation, which almost certainly is warmer (from absorbed body heat) than the outside vapor which is soaking the shell? Isn't this sort of like condensation in reverse? Instead of warm body vapor rising through the layers down's loft until it reaches a temp, quite possibly inside the breathable shell, where it condenses into liquid or frozen water, we have colder vapor trying to cross an area that is warmer than outside the shell. Will condensation of fog occur inside the warmer down? Is fog a vapor that can condense into liquid in the first place? Isn't it already liquid? I don't know much of the above.

Regardless, what is their non VB trick to dealing with dew points inside a quilt? Layering bags of different types. You know how people around here love to layer quilts when they have to deal with a temp colder than any 1 quilt they own is rated for? Well these other guys like to get the bulk of their warmth from a down quilt, but sometimes- especially in really wet country, they go with a down quilt much lighter than the temps call for. Say for example, they expect no colder than 20F, so they go with a 40F quilt.

Very light. But then they add the lightest possible CS or PL over bag, summer rated and sized to easily fit over the TQ without compressing the down. So now this combo is rated for at least the lowest temp they are expecting, 20F.

What does this accomplish? Though still not the most weight efficient method, the main thing that is accomplished is the the dew point that might have caused condensation inside the down is probably now at worst case out in the synthetic insulation. Which handles the moisture much better, is less likely to lose loft, and will dry much quicker. Since they usually have to pack up quickly the next morning, the drier down can be packed separately from the damp outer CS bag. If the sun pops out, they can stop for a quick drying of the outer CS quilt.

Also, now if they sleep in the added insulation of clothing which might be damp from hiking, as their body heat dries it out, and that vapor rises towards the shell, it is now far less likely to hit the dew point and re-condense inside of the down. If it does not make it past the outer shell, it probably will condense in the synthetic over quilt insulation where it does less damage. And they wake up with dry clothing. These guys report much improvement in being ale to maintain loft in their down quilts on long, wet trips. Maybe this would actually be a useful approach? A combo approach with some of the best of both worlds? (Or, VB clothing and forget all of that! )

[HandyRandy]

Speaking of $10 bets, I reckon JustBill should be chiming in soon.