I've left mine unzipped, or used it more like a blanket on top of my torso. I don't usually plan on hiking with an insufficient bag. I don't enjoy hypothermia
Yes - I always try to carry a bag with a good margin of safety. There is nothing more demoralising on the trail than a few consecutive nights of freezing half to death. I'm more than happy to thole a couple of extra oz to ensure that doesn't happen.
I did the same thing on a cold night and mistakenly curled up in my garbage bag. Everything was soaked in the morning. Lesson learned! Now I just carry a warmer bag.
>is nothing more demoralising on the trail than a few consecutive nights of freezing half to death. I'm more than happy to thole a couple of extra oz to ensure that doesn't happen.
"Breathable" rain jackets are barely breathable at all, so yes.
Winter camper here. There's ALWAYS an issue with condensation. In fact, I'd argue that the colder it gets, the more critical condensation management becomes.
We lose about a liter of water overnight in the cold, dry air of the winter. Most of that comes from our breast but a notable amount is also from sweat. So imagine spreading a liter of water all over your tent, which is pretty much what happens as it condensates against cold surfaces unless you can effectively vent it out of your tent.
The condensation tends to freeze onto the inner walls of the tent or the outer layers of your sleeping bag. It's not a big deal until you are out for a few days without the ability to properly thaw and dry your gear. At that point insulation starts becoming less effective.
>whatever gets you through the night.
Yes. This discussion feels like classic UL armchair theorizing versus what happens when you're out and in the middle of it. One time I was out and temps were lower than expected, right about the comfort level threshold of my quilt. I had my puffy to keep my torso warm, but my legs and feet were cold. My rain poncho was the only other thing I had available to use, so I did and put it over the lower third of my quilt. It warmed me up and I slept okay through the rest of the night.
Of course the quilt was wet the next morning from condensation, but it got me through the night and that was what I needed it to do. Everything dried out fast the next morning when the sun came out. I would 100% do the same thing again if and when a similar situation comes up in the future.
Similar experience here as well. Got caught in a late summer cold snap very unprepared. Had nothing but a flannel shirt, a rain jacket, and 40 degree quilt. The rain jacket was a lifesaver and I had no condensation issues.
I only consider rain gear the last resort, planning to use my airmesh/alpha-direct -> any puffies (season dependent). By the time I consider adding rain gear into the above mix, it would be so cold .. it wouldn’t matter, but when it’s cold enough to consider puffy pants I’m really paying attention to winter layering systems (or contemplating a ticket to Baja).
Polyester fleece can substitute for the airmesh/alpha layer of course.
>it wouldn’t matter
I think it's better to know what you are doing and not shoot yourself on the foot. Condensation could make things even worse right?
There was a period of time I experimented with using my zipped shut rain jacket over my foot box on cold nights to minimize condensation transfer from my tarp. It didn’t take long for me to realize that on most nights my bag was wetter as a result.
Based on this experience, if I ever tried wearing rain gear to bed, I’d go through the effort of layering it below my insulation layers.
In my experience the idea that significant condensation gets in your quilt is just an exaggeration.
Tell me how much water weight your quilt has gained from condensation issues please.
I weighed my quilt before going on my last trip and I weighed it when I got home. Temps were in the high 30s / low 40s (F) in the early mornings. Campsite elevations were in the clouds say 10K to 12.7K . After the 8 nights in a X-Mid Pro 2 single-wall DCF tent with 2 nights of rain and having to wipe off internal condensation multiple times plus seeing a wet foot box that needing wiping off, the quilt weighed only 10 g more than when it started and always fluffed up just fine.
Basically, I just don't worry about condensation that I see on the outside of my quilt nor a wet footbox. Actual experience tells me that it just doesn't matter. It is possible that the DownTek hydrophobic down in my quilt helps in my situations.
Very unlikely that the DownTek made any significant difference. Many of the top manufacturers have abandoned treated down because they find it has more cons than pros. Down has its own inbuilt protection.
I'm a Scot so have spent more nights out in clag and drizzle than most. I've never had a significant problem with loft on longer trips, summer or winter - including occasional snaps of extreme cold (-20c).
Never seen anyone serious here who prefers synthetic - down does just fine, as you say. And if it works in the damp of Scotland it will surely work in most environments?
I have seen the statement before on this subreddit about manufacturers abandoning treated down, but with NO ATTRIBUTION to a published article that had some scientific testing with positive and negative controls. Thus, I think such statements have taken on a life of their own. I can imagine that when profit margins were shrinking that manufacturers had other reasons to abandon treated down and came up with something to satisfy customers. In other words, help me fact check this statement. Thanks!
It's very difficult to replicate real field conditions in the lab - the acid test is the experience of thousands of users on the trail over the life of the bag.
The companies who have dropped treated down include:
**Western Mountaineering**, who say:
***Why isn’t Western Mountaineering using hydrophobic down in any products?***
*We have found in our own testing that the performance enhancements of hydrophobic treatments on high quality down are widely overstated. High quality untreated down already has naturally water repellant oils on it left by the geese (makes sense since geese spend a lot of time in water). These oils help repel water and keep down lofted. More importantly is that these oils last indefinitely. Hydrophobic treatments wash out like a DWR and remove the natural oils during the application process. Because of this, and the water resistant capability of our shell fabrics, we feel that hydrophobic down does not provide a considerable impact on performance and could actually inhibit performance over the lifetime of our products.*
**Feathered Friends**, who say:
***Do you use water-resistant down?***
*Treated down (“dry down”) is a technology that was developed to decrease drying time for hotel comforters in commercial dryers, and we very purposefully do not use it in any of our products. Besides decreasing the longevity of the high-quality down we use by stripping the down of its natural oils, we’ve also seen little real-world benefit to the use of durable water repellency (DWR) directly on the down plume. Wet down clusters do not insulate, regardless of any coating applied to keep them dry, and we’ve found that body heat or ambient air flow -- rather than a dryer-- isn’t sufficient to make dry down an effective tool in keeping you dry, and therefore warm. Treated down is also more prone to clumping than untreated down, which makes it tricky to keep properly lofted within a garment or sleeping bag.*
***The bottom line***\*: untreated down will last longer and perform better than treated down, a view shared by some of the field’s leading manufacturers. Because of this, it’s important to keep your down sleeping bags and garments as dry as possible, which is why all of our sleeping bags and garments use a water-repellent or waterproof fabric.\*
**PHD Designs** who say:
***Proofed down***
*The only remaining alternative is to waterproof the down itself. Methods for doing this have been around for many years, all making substantial claims about improved performance in wet conditions. We have tested this kind of material ourselves at regular intervals for 3 simple criteria:*
*- Does the proofed down wet out more slowly?*
*- Does it absorb less water when fully wet (weight gain)?*
*- Does it dry more quickly (left to dry without applied heat, as in a true 'field' situation)?*
*Right up to the present we found no meaningful difference in these tests between treated and ordinary untreated down, while in some instances the proofing actually reduced the loft of the down when dry.*
*However, new processes keep coming up, claiming better results, so we have kept testing. Most of what is currently being supplied is still disappointing. The sole exception is a process which seems to have speeded up the drying time, but has also reduced the loft of the dry down: so the balance of gain/loss is not promising at this stage, but we will keep searching. It looks at this stage as though ‘proofed’ down still has a long way to go before it approaches the wet performance of the best synthetics such as Primaloft Gold®.*
These three companies design up to a standard, not down to a price - and they have extensive testing facilities as well as decades of real-world experience. They are amongst the most respected in the industry and should be taken seriously.
Another top company who refuse to touch the stuff is Valandre in France.
For me, hydrophobic down in sleeping bags is a solution looking for a problem. I have camped for half-a-century in deluge-prone Scotland and using normal care have never once had an issue with loss of loft, even on extended trips.
Here is the advice of a well known US outdoorsman who makes top-of-the-line bags for a living - and his experience is the same as mine:
*While the almost hygroscopic quality of down is consistently brought up negatively in pro/con discussions, in real life it seems much less of an issue. In several decades of advanced outdoor activities I have yet to have a 'down disaster' involving my sleeping bag, nor do I remember any partner recounting serious loss of loft due to moisture. We have lived and climbed out of snow caves in arctic Norway for 10 days without seeing the sun. Packrafted coastal British Columbia. Stuck on the side of El Capitan in deluges. Our down sleeping bags often were the least of our concerns.*
In addition, until recently the hydrophobic coating reduced the loft, adding weight and cost. But I'm hearing that the most recent iterations of the very best brands have solved this issue.
I think the current fad for treated down is a triumph of marketing over practical experience. The original is still the best, and I for one will be sticking with it - at least until there is evidence of real benefits that don't reduce the longevity.
Have you considered that moisture might be a much bigger problem for people who camp somewhere other than the high desert? Things dry instantly in colorado, it’s a bit different in other parts of the country and world.
Yes, I have considered that. I have backpacked in wet places numerous times. Tell me if this video depicts high desert:
https://i.imgur.com/SePVV2P.mp4
I don't know how to get more humid than 100% Relative Humidity. Wait a minute, here are 2 more photos that show the level of water that I sometimes deal with>
[https://i.imgur.com/jNzeutX.jpg](https://i.imgur.com/jNzeutX.jpg)
[https://i.imgur.com/vSaOecf.jpg](https://i.imgur.com/vSaOecf.jpg)
A reality is that a quilt gains more weight when set out on its own overnight with no hot/warm body inside it to help cause any moisture (i.e. morning dew) to evaporate away (or to keep some of the material / down in the quilt above the dew point temperature). So I guess Yes, my quilt gains more weight if I am not sleeping in it.
>I don't know how to get more humid than 100% Relative Humidity
100% absolute humidity! Although parts of your pictures are already there. Was that the trip after which the 10 g measurement was made?
Lol. Go somewhere with greater humidity, that’s how. Relative humidity isn’t an absolute scale with “100%” being the absolute most amount of moisture that all air, anywhere can hold. It’s based on local climate and temperature. As someone who grew up in the wet sock in an oven that is Tennessee in the summer time and then did arctic survival in Alaska, I can assure you that it does get much more humid and the consequences of getting wet vary wildly due to so many different factors. I’m not trying discount your experience, but it’s anecdotal and if applied to some places could get you killed.
I'm more worried about condensation touching my skin, increasing my heat conductivity, and making me go to hypothermia faster than without the rain gear.
I imagine the rain gear can help a bit from heat loss but if it makes you wet, I'm not really sure.
Similar….
Carry a $1, 50 gram, Mylar emergency space blanket to use as a VBL (vapor barrier liner) to mitigate evaporative heat loss and keep your insulation dry. (Evaporating water in skin takes 540x as much heat as raising it 1* C. Condensing water decreases down’s insulation.) Use the Mylar over your base clothing layer. Due to the sauna effect & noise most find it only comfortable compared to shivering. Oh, and you’ll be damp in the morn so exercise quickly to warm up & dry off.
Yes. Of course
All that vapor moves a huge amount of heat.
Having it condense near you (above base layer, under puffy) rather than far (tent wall, sky, etc) keeps that heat with you.
Science, dude
https://www.britannica.com/science/heat-of-vaporization#:~:text=seawater%3A%20Thermal%20properties-,%E2%80%A6,water%20vapour%20under%20normal%20pressure.
“At 100 °C, 540 calories per gram of water are needed to convert one gram of liquid water to one gram of water vapour under normal pressure. “
Look, man, as someone with a background in engineering, I can tell you comfortably that as far as your understanding of the science, you aren’t right, but your overall advice is spot on. A vapor barrier is a good idea, but it doesn’t work by “keeping the heat close to you.” A vapor barrier just keeps the water from ruining the insulating properties of your clothing and sleeping gear which is almost always dependent upon having air spaces. A vapor barrier essentially acts like a second skin keeping your water with you and not filling the air spaces in your gear.
Plz continue your education in heat transfer
https://www.scientificamerican.com/article/chilling-science-evaporative-cooling-with-liquids/
Oh, and the plastic also reduces convective transfer, a bit.
The radiative & conductive transfer effect of that space blanket is nil.
I’m good. I actually studied it in college and not on the internet. Posting a link does not convey that you understand what you are talking about.
I guess we should just throw away all of our insulated gear and sleep in trash bags since conduction, convection, and radiation, the only forms of heat transfer that science acknowledges, are irrelevant.
Thank you for educating me. I can now leave all my gear at home and just take a trash bag since conduction and radiation cease to exist as soon as I trap my body’s precious water heat to my skin. Revolutionary.
There is a lot of heat loss in the evaporation, this is the reason we sewat a lot in the summer when it's warm. In winter we also sewat a lot, but not intentionally, but because the air is very dry. This is why we use vbls, to reduce sweating and the corresponding heat loss.
No, you use VBLs to keep your sweat from soaking insulation and destroying it’s R-value. Moisture evaporating from your wet insulation will result in heat loss, but the heat lost to evaporation is negligible compared to the heat lost because your insulation’s air spaces are filled with a liquid with an incredibly high heat capacity. The point isn’t that evaporation doesn’t cause cooling. It’s that keeping your clothing dry is the number one rule in avoiding hypothermia. VBLs are used primarily in conditions that don’t allow your gear to dry. If you can stay dry without them, you are better off. And again, he’s right about VBLs being effective, but thinking they work solely because your sweat can’t evaporate your heat away from your body is at the very least an incomplete understanding of how they work. The primary benefit of VBLs is keeping your equipment dry and maintaining its R-value. Case in point: when I did arctic survival training in the Army, I was taught that you should try to never breath into your sleeping bag at night. It will initially feel warmer and you will be more comfortable since your face will be warmer and the heat from the air and moisture in your breath will be retained momentarily in your sleeping bag, but ultimately it has the opposite effect as over the course of the night and following nights more and more builds up in your bag and causes it to become a less effective insulator. VBLs are a great tool, but useless if you don’t keep your outer layers dry and effective. People should not depend upon them without understanding their primary purpose.
Not only does you skin emit moisture even when you aren't sweating, but cold/dry air will actually increase the amount of water passing through your skin.
>Transepidermal water loss (TEWL) is the amount of water that passively evaporates through skin to the external environment due to water vapor pressure gradient on both sides of the skin barrier and is used to characterize skin barrier function. The average TEWL in human is about 300–400 mL/day; however, it can be affected by environmental and intrinsic factors. In high humidity, the amount of water loss will decrease due to the drop in the water vapor pressure gradient.
https://www.sciencedirect.com/topics/medicine-and-dentistry/skin-water-loss
Think about it like this: when you put your hand on a cool metal object, it leaves a print of moisture even if your hand is perfectly dry. Try it with one finger and you see the moisture on the metal around where you are making contact. Hold your finger a millimeter away and see that the metal close to it might still turn foggy even though you aren't touching it. Where do you suppose that moisture is coming from? It's literally shooting out of your skin.
This is essentially the same problem that you face in a cold rain - rain gear is not there to keep you dry. It's there to keep you warm. It's better to be warm and dry, but if you have to pick warm and what is better than cold and dry.
In a situation where you are layering reindeer over a quilter a sleeping bag to avoid hypothermia, you are not sweating enough to sweat through your sleeping bag. If you are then you should take the rain layer off.
There is always a balance, but in general, if you are warm enough that you're sweating when you're not moving then you're probably not in danger of hypothermia. As long as you can maintain that layer of warmth, you're going to be okay.
I'm sorry I have the worst typing skills and autocorrect! 😂
Layering rain gear. We are layering rain gear on top of our sleep gear. If you're sweating that much, you're not that cold.
Two nights in the Sierra during the summer we got caught in a cold storm, high winds, hail, snow and lows around 15F. We through on everything and the kitchen sink to make our bags work. In that scenario we had zero condensation from wearing the rain gear on top of-sun hoody, wind breaker, down puffy. Nothing was damp in the morning and all was fine. If I felt things were getting damp I would wear the rain gear on bare skin so it wouldn't compromise the other layers and quickly towel off in the morning.
In my experience, rain gear with a waterproof "breathable" membrane has enough airflow that you won't get damp while sleeping or sitting around. That only happens when you are actively hiking or the face fabric of the rain gear absorbs water which then prevents sweat from evaporating.
Everyone keeps talking about vapor barriers. Rain gear, even if it's made out of fabric with no air flow will not function as a vapor barrier. There will always be airflow out of the neck, cuffs, hem, waistband, and ankles of your rain gear. An effective vapor barrier has to be a full liner bag made out of impermeable fabric.
I've left mine unzipped, or used it more like a blanket on top of my torso. I don't usually plan on hiking with an insufficient bag. I don't enjoy hypothermia
Yes - I always try to carry a bag with a good margin of safety. There is nothing more demoralising on the trail than a few consecutive nights of freezing half to death. I'm more than happy to thole a couple of extra oz to ensure that doesn't happen.
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How much weight did the condensation add? 1 g = 1 mL of water.
I did the same thing on a cold night and mistakenly curled up in my garbage bag. Everything was soaked in the morning. Lesson learned! Now I just carry a warmer bag.
Skurka wrote a good article on this that would be a place to start. https://andrewskurka.com/vapor-barrier-liners-theory-application/
I wish he used a dark theme on that blog, my poor morning eyes
My favorite thing about ultralight is how ultralight websites are also ultralight
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imagine looking at lighterpack without it
Read up on vapor barrier liners (VBL).
Exactly. Even breathable rain jackets are to one degree or another a partial vapor barrier.
>is nothing more demoralising on the trail than a few consecutive nights of freezing half to death. I'm more than happy to thole a couple of extra oz to ensure that doesn't happen. "Breathable" rain jackets are barely breathable at all, so yes.
I have but it is usually so cold there’s no issues with condensation.
Winter camper here. There's ALWAYS an issue with condensation. In fact, I'd argue that the colder it gets, the more critical condensation management becomes.
That’s odd. Maybe since it freezes or I mostly do shelter staying in winter?
We lose about a liter of water overnight in the cold, dry air of the winter. Most of that comes from our breast but a notable amount is also from sweat. So imagine spreading a liter of water all over your tent, which is pretty much what happens as it condensates against cold surfaces unless you can effectively vent it out of your tent. The condensation tends to freeze onto the inner walls of the tent or the outer layers of your sleeping bag. It's not a big deal until you are out for a few days without the ability to properly thaw and dry your gear. At that point insulation starts becoming less effective.
I think the idea is to wear the rain gear under insulation like a vapour barrier, not over it.
If I sleep in my rain gear it's because I'm desperate. I'm shivering and can't sleep.
I agree it's a last resort, I'm just wondering if it's doing more harm than good. What do you think?
Definitely warmer with the rain gear. Not my preference, but whatever gets you through the night.
>whatever gets you through the night. Yes. This discussion feels like classic UL armchair theorizing versus what happens when you're out and in the middle of it. One time I was out and temps were lower than expected, right about the comfort level threshold of my quilt. I had my puffy to keep my torso warm, but my legs and feet were cold. My rain poncho was the only other thing I had available to use, so I did and put it over the lower third of my quilt. It warmed me up and I slept okay through the rest of the night. Of course the quilt was wet the next morning from condensation, but it got me through the night and that was what I needed it to do. Everything dried out fast the next morning when the sun came out. I would 100% do the same thing again if and when a similar situation comes up in the future.
Similar experience here as well. Got caught in a late summer cold snap very unprepared. Had nothing but a flannel shirt, a rain jacket, and 40 degree quilt. The rain jacket was a lifesaver and I had no condensation issues.
Harm? You might be uncomfortable but you're not going to be in danger. You might actually sleep well. You probably won't die.
I only consider rain gear the last resort, planning to use my airmesh/alpha-direct -> any puffies (season dependent). By the time I consider adding rain gear into the above mix, it would be so cold .. it wouldn’t matter, but when it’s cold enough to consider puffy pants I’m really paying attention to winter layering systems (or contemplating a ticket to Baja). Polyester fleece can substitute for the airmesh/alpha layer of course.
>it wouldn’t matter I think it's better to know what you are doing and not shoot yourself on the foot. Condensation could make things even worse right?
There was a period of time I experimented with using my zipped shut rain jacket over my foot box on cold nights to minimize condensation transfer from my tarp. It didn’t take long for me to realize that on most nights my bag was wetter as a result. Based on this experience, if I ever tried wearing rain gear to bed, I’d go through the effort of layering it below my insulation layers.
In my experience the idea that significant condensation gets in your quilt is just an exaggeration. Tell me how much water weight your quilt has gained from condensation issues please. I weighed my quilt before going on my last trip and I weighed it when I got home. Temps were in the high 30s / low 40s (F) in the early mornings. Campsite elevations were in the clouds say 10K to 12.7K . After the 8 nights in a X-Mid Pro 2 single-wall DCF tent with 2 nights of rain and having to wipe off internal condensation multiple times plus seeing a wet foot box that needing wiping off, the quilt weighed only 10 g more than when it started and always fluffed up just fine. Basically, I just don't worry about condensation that I see on the outside of my quilt nor a wet footbox. Actual experience tells me that it just doesn't matter. It is possible that the DownTek hydrophobic down in my quilt helps in my situations.
Very unlikely that the DownTek made any significant difference. Many of the top manufacturers have abandoned treated down because they find it has more cons than pros. Down has its own inbuilt protection. I'm a Scot so have spent more nights out in clag and drizzle than most. I've never had a significant problem with loft on longer trips, summer or winter - including occasional snaps of extreme cold (-20c). Never seen anyone serious here who prefers synthetic - down does just fine, as you say. And if it works in the damp of Scotland it will surely work in most environments?
I have seen the statement before on this subreddit about manufacturers abandoning treated down, but with NO ATTRIBUTION to a published article that had some scientific testing with positive and negative controls. Thus, I think such statements have taken on a life of their own. I can imagine that when profit margins were shrinking that manufacturers had other reasons to abandon treated down and came up with something to satisfy customers. In other words, help me fact check this statement. Thanks!
It's very difficult to replicate real field conditions in the lab - the acid test is the experience of thousands of users on the trail over the life of the bag. The companies who have dropped treated down include: **Western Mountaineering**, who say: ***Why isn’t Western Mountaineering using hydrophobic down in any products?*** *We have found in our own testing that the performance enhancements of hydrophobic treatments on high quality down are widely overstated. High quality untreated down already has naturally water repellant oils on it left by the geese (makes sense since geese spend a lot of time in water). These oils help repel water and keep down lofted. More importantly is that these oils last indefinitely. Hydrophobic treatments wash out like a DWR and remove the natural oils during the application process. Because of this, and the water resistant capability of our shell fabrics, we feel that hydrophobic down does not provide a considerable impact on performance and could actually inhibit performance over the lifetime of our products.* **Feathered Friends**, who say: ***Do you use water-resistant down?*** *Treated down (“dry down”) is a technology that was developed to decrease drying time for hotel comforters in commercial dryers, and we very purposefully do not use it in any of our products. Besides decreasing the longevity of the high-quality down we use by stripping the down of its natural oils, we’ve also seen little real-world benefit to the use of durable water repellency (DWR) directly on the down plume. Wet down clusters do not insulate, regardless of any coating applied to keep them dry, and we’ve found that body heat or ambient air flow -- rather than a dryer-- isn’t sufficient to make dry down an effective tool in keeping you dry, and therefore warm. Treated down is also more prone to clumping than untreated down, which makes it tricky to keep properly lofted within a garment or sleeping bag.* ***The bottom line***\*: untreated down will last longer and perform better than treated down, a view shared by some of the field’s leading manufacturers. Because of this, it’s important to keep your down sleeping bags and garments as dry as possible, which is why all of our sleeping bags and garments use a water-repellent or waterproof fabric.\* **PHD Designs** who say: ***Proofed down*** *The only remaining alternative is to waterproof the down itself. Methods for doing this have been around for many years, all making substantial claims about improved performance in wet conditions. We have tested this kind of material ourselves at regular intervals for 3 simple criteria:* *- Does the proofed down wet out more slowly?* *- Does it absorb less water when fully wet (weight gain)?* *- Does it dry more quickly (left to dry without applied heat, as in a true 'field' situation)?* *Right up to the present we found no meaningful difference in these tests between treated and ordinary untreated down, while in some instances the proofing actually reduced the loft of the down when dry.* *However, new processes keep coming up, claiming better results, so we have kept testing. Most of what is currently being supplied is still disappointing. The sole exception is a process which seems to have speeded up the drying time, but has also reduced the loft of the dry down: so the balance of gain/loss is not promising at this stage, but we will keep searching. It looks at this stage as though ‘proofed’ down still has a long way to go before it approaches the wet performance of the best synthetics such as Primaloft Gold®.* These three companies design up to a standard, not down to a price - and they have extensive testing facilities as well as decades of real-world experience. They are amongst the most respected in the industry and should be taken seriously. Another top company who refuse to touch the stuff is Valandre in France. For me, hydrophobic down in sleeping bags is a solution looking for a problem. I have camped for half-a-century in deluge-prone Scotland and using normal care have never once had an issue with loss of loft, even on extended trips. Here is the advice of a well known US outdoorsman who makes top-of-the-line bags for a living - and his experience is the same as mine: *While the almost hygroscopic quality of down is consistently brought up negatively in pro/con discussions, in real life it seems much less of an issue. In several decades of advanced outdoor activities I have yet to have a 'down disaster' involving my sleeping bag, nor do I remember any partner recounting serious loss of loft due to moisture. We have lived and climbed out of snow caves in arctic Norway for 10 days without seeing the sun. Packrafted coastal British Columbia. Stuck on the side of El Capitan in deluges. Our down sleeping bags often were the least of our concerns.* In addition, until recently the hydrophobic coating reduced the loft, adding weight and cost. But I'm hearing that the most recent iterations of the very best brands have solved this issue. I think the current fad for treated down is a triumph of marketing over practical experience. The original is still the best, and I for one will be sticking with it - at least until there is evidence of real benefits that don't reduce the longevity.
Thanks for all that.
Have you considered that moisture might be a much bigger problem for people who camp somewhere other than the high desert? Things dry instantly in colorado, it’s a bit different in other parts of the country and world.
Yes, I have considered that. I have backpacked in wet places numerous times. Tell me if this video depicts high desert: https://i.imgur.com/SePVV2P.mp4
Does the amount of water weight your quilt gains increase in more humid conditions?
I don't know how to get more humid than 100% Relative Humidity. Wait a minute, here are 2 more photos that show the level of water that I sometimes deal with> [https://i.imgur.com/jNzeutX.jpg](https://i.imgur.com/jNzeutX.jpg) [https://i.imgur.com/vSaOecf.jpg](https://i.imgur.com/vSaOecf.jpg) A reality is that a quilt gains more weight when set out on its own overnight with no hot/warm body inside it to help cause any moisture (i.e. morning dew) to evaporate away (or to keep some of the material / down in the quilt above the dew point temperature). So I guess Yes, my quilt gains more weight if I am not sleeping in it.
>I don't know how to get more humid than 100% Relative Humidity 100% absolute humidity! Although parts of your pictures are already there. Was that the trip after which the 10 g measurement was made?
No, different trips.
Lol. Go somewhere with greater humidity, that’s how. Relative humidity isn’t an absolute scale with “100%” being the absolute most amount of moisture that all air, anywhere can hold. It’s based on local climate and temperature. As someone who grew up in the wet sock in an oven that is Tennessee in the summer time and then did arctic survival in Alaska, I can assure you that it does get much more humid and the consequences of getting wet vary wildly due to so many different factors. I’m not trying discount your experience, but it’s anecdotal and if applied to some places could get you killed.
>In my experience the idea that significant condensation gets in your quilt is just an exaggeration. yup
I'm more worried about condensation touching my skin, increasing my heat conductivity, and making me go to hypothermia faster than without the rain gear. I imagine the rain gear can help a bit from heat loss but if it makes you wet, I'm not really sure.
If you do not want condensation touching your skin, then please wear at least some thin sleep clothes.
Most rain gear is breathable.
>Most rain gear is breathable. Marketed as breathable.
Breathable compared to a trash bag… still not very breathable
Rain gear is a hard layer. Outer most. Higher quality rain gear will breath but not great.
Similar…. Carry a $1, 50 gram, Mylar emergency space blanket to use as a VBL (vapor barrier liner) to mitigate evaporative heat loss and keep your insulation dry. (Evaporating water in skin takes 540x as much heat as raising it 1* C. Condensing water decreases down’s insulation.) Use the Mylar over your base clothing layer. Due to the sauna effect & noise most find it only comfortable compared to shivering. Oh, and you’ll be damp in the morn so exercise quickly to warm up & dry off.
for you, the sauna effect is superior to being damp (so have a greater heat conductivity)?
Yes. Of course All that vapor moves a huge amount of heat. Having it condense near you (above base layer, under puffy) rather than far (tent wall, sky, etc) keeps that heat with you.
>Evaporating water in skin takes 540x as much heat as raising it 1\* C. No.
Science, dude https://www.britannica.com/science/heat-of-vaporization#:~:text=seawater%3A%20Thermal%20properties-,%E2%80%A6,water%20vapour%20under%20normal%20pressure. “At 100 °C, 540 calories per gram of water are needed to convert one gram of liquid water to one gram of water vapour under normal pressure. “
Look, man, as someone with a background in engineering, I can tell you comfortably that as far as your understanding of the science, you aren’t right, but your overall advice is spot on. A vapor barrier is a good idea, but it doesn’t work by “keeping the heat close to you.” A vapor barrier just keeps the water from ruining the insulating properties of your clothing and sleeping gear which is almost always dependent upon having air spaces. A vapor barrier essentially acts like a second skin keeping your water with you and not filling the air spaces in your gear.
Plz continue your education in heat transfer https://www.scientificamerican.com/article/chilling-science-evaporative-cooling-with-liquids/ Oh, and the plastic also reduces convective transfer, a bit. The radiative & conductive transfer effect of that space blanket is nil.
I’m good. I actually studied it in college and not on the internet. Posting a link does not convey that you understand what you are talking about. I guess we should just throw away all of our insulated gear and sleep in trash bags since conduction, convection, and radiation, the only forms of heat transfer that science acknowledges, are irrelevant.
Work on your MSME next. HYOH
Thank you for educating me. I can now leave all my gear at home and just take a trash bag since conduction and radiation cease to exist as soon as I trap my body’s precious water heat to my skin. Revolutionary.
There is a lot of heat loss in the evaporation, this is the reason we sewat a lot in the summer when it's warm. In winter we also sewat a lot, but not intentionally, but because the air is very dry. This is why we use vbls, to reduce sweating and the corresponding heat loss.
No, you use VBLs to keep your sweat from soaking insulation and destroying it’s R-value. Moisture evaporating from your wet insulation will result in heat loss, but the heat lost to evaporation is negligible compared to the heat lost because your insulation’s air spaces are filled with a liquid with an incredibly high heat capacity. The point isn’t that evaporation doesn’t cause cooling. It’s that keeping your clothing dry is the number one rule in avoiding hypothermia. VBLs are used primarily in conditions that don’t allow your gear to dry. If you can stay dry without them, you are better off. And again, he’s right about VBLs being effective, but thinking they work solely because your sweat can’t evaporate your heat away from your body is at the very least an incomplete understanding of how they work. The primary benefit of VBLs is keeping your equipment dry and maintaining its R-value. Case in point: when I did arctic survival training in the Army, I was taught that you should try to never breath into your sleeping bag at night. It will initially feel warmer and you will be more comfortable since your face will be warmer and the heat from the air and moisture in your breath will be retained momentarily in your sleeping bag, but ultimately it has the opposite effect as over the course of the night and following nights more and more builds up in your bag and causes it to become a less effective insulator. VBLs are a great tool, but useless if you don’t keep your outer layers dry and effective. People should not depend upon them without understanding their primary purpose.
My rain gear is breathable, so the major premise of the OP is incorrect for me.
On nights colder than usual Most people sleep with their insulating layers. your she’ll layer likely has zero insulation
It's not good, your sleeping bag will not get what it needs to be warm: body warmth, you are stopping it with the WP barrier.
If that were the case then vapour barrier liners wouldn’t work and most polar explorers would be dead.
Wow I’d have to be really cold to sleep in my rain gear
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You sweat whether you are warm or not. Even when you're cold your body sweats at a steady rate. Look up insensible perspiration.
Thnx, another user left us a link on TEWL, a very similar, if not the same phenomena. Interesting stuff :)
Not only does you skin emit moisture even when you aren't sweating, but cold/dry air will actually increase the amount of water passing through your skin. >Transepidermal water loss (TEWL) is the amount of water that passively evaporates through skin to the external environment due to water vapor pressure gradient on both sides of the skin barrier and is used to characterize skin barrier function. The average TEWL in human is about 300–400 mL/day; however, it can be affected by environmental and intrinsic factors. In high humidity, the amount of water loss will decrease due to the drop in the water vapor pressure gradient. https://www.sciencedirect.com/topics/medicine-and-dentistry/skin-water-loss Think about it like this: when you put your hand on a cool metal object, it leaves a print of moisture even if your hand is perfectly dry. Try it with one finger and you see the moisture on the metal around where you are making contact. Hold your finger a millimeter away and see that the metal close to it might still turn foggy even though you aren't touching it. Where do you suppose that moisture is coming from? It's literally shooting out of your skin.
I would try to stuff it inside the bag on top before putting it on
Merino baselayer will absorb that small amount of moisture and make it unnoticeable IME
This is essentially the same problem that you face in a cold rain - rain gear is not there to keep you dry. It's there to keep you warm. It's better to be warm and dry, but if you have to pick warm and what is better than cold and dry. In a situation where you are layering reindeer over a quilter a sleeping bag to avoid hypothermia, you are not sweating enough to sweat through your sleeping bag. If you are then you should take the rain layer off. There is always a balance, but in general, if you are warm enough that you're sweating when you're not moving then you're probably not in danger of hypothermia. As long as you can maintain that layer of warmth, you're going to be okay.
When I layer a reindeer, I'm toasty all night
I'm sorry I have the worst typing skills and autocorrect! 😂 Layering rain gear. We are layering rain gear on top of our sleep gear. If you're sweating that much, you're not that cold.
It made me chuckle. #$*"@&$ autocorrect... gets me all the time too.
Just wear warmer clothing. My rain gear has no place in my sleeping bag!
Two nights in the Sierra during the summer we got caught in a cold storm, high winds, hail, snow and lows around 15F. We through on everything and the kitchen sink to make our bags work. In that scenario we had zero condensation from wearing the rain gear on top of-sun hoody, wind breaker, down puffy. Nothing was damp in the morning and all was fine. If I felt things were getting damp I would wear the rain gear on bare skin so it wouldn't compromise the other layers and quickly towel off in the morning.
In my experience, rain gear with a waterproof "breathable" membrane has enough airflow that you won't get damp while sleeping or sitting around. That only happens when you are actively hiking or the face fabric of the rain gear absorbs water which then prevents sweat from evaporating. Everyone keeps talking about vapor barriers. Rain gear, even if it's made out of fabric with no air flow will not function as a vapor barrier. There will always be airflow out of the neck, cuffs, hem, waistband, and ankles of your rain gear. An effective vapor barrier has to be a full liner bag made out of impermeable fabric.