We’re having a warm spell of weather in Stockholm right now. This could be a timely reminder that everything comes to an end, and soon we will have to pack way our skates and skis and igloos, and get ready for the Swedish Summer, coming in the form of clouds of pollen, clouds of mosquitos and clouds. It’s also a timely reminder that we should get our priorities straight and leave jobs, partners and families to one side, don our wooly hats and get out into the snow as much as possible before it’s all gone.
Back-country skiing through the burnt landscape of Tyresta national park.
The good times I’ve had so far this season owe a lot to the gear that made harsh conditions comfortable, none more so than the sleep system. No matter how good gear you have in terms of rucksacks, skis, gloves, tents and all that shit, if you’re not getting a solid nights sleep at the end of the day, you will have a shitty trip. A bad sleeping bag means a rough night, and I am sure everyone who has tried Winter camping has had one of those nights. Those nights when the weatherman was on crack and forecasted warm temperatures, instead it drops below -30 C° and you end up trying to sleep through the night with insufficiently warm gear. Shivering, chilled to the bone, twisting and turning to try and find some warmer position. Waiting hour after interminable hour until the cold grey fingers of dawn start to reach into your tent. Fucking. Horrible. To really enjoy Winter camping the quality of your sleeping-gear has to be excellent.
Unfortunately Winter sleeping systems can be a pain in the neck. Synthetic bags are reliable, they can be literally soaking wet and yet still functionally retain heat. However they are also heavy, heavy enough that if you want to be out below -10 °C, you’ll need around 2 kgs of sleeping bag. And they compress like shit, even a warm-weather synthetic bag takes up a lot of space. Down bags are half the weight and compress much better but they turn from thick fluffy marshmallows of warmth into thin dribbling rags if they get too wet.
The terrifying wet surface of a down-quilt in the morning.
If the temperatures are well below 0 °C, and if you happen to be the kind of person that is largely made up of water, then you can count on waking up in a bag a few dozen grammes heavier with condensation from the sweat and breath of your nocturnal slumber. I occasionally do submission wrestling competitions, and when cutting weight it was always the morning weighting that was most rewarding, it’s not unusual to drop a kilo during the night. My girlfriend hasn’t complained about me shitting the bed in years, so the weight loss must be due to water vapour. That’s a litre of water a night, some of it ending up in your down bag.
A few millilitres of water in your down reduces loft a little, but is not a problem for an overnight trip. On longer trips you can try drying your bag out in the mornings, but in Winter it’s not effective and sometimes the weather can be an uncooperative asshole. You can also buy bags with heavier waterproof fabrics, but this negates the nice weight savings from down, and reduces loft. You can also have a down under-quilt, and throw a synthetic over-quilt on top of that. The theory is that the moisture from your body passes through the down quilt without condensing due to the insulation of the synthetic quilt. And then when it hits the synthetic quilt it condenses there, but that doesn’t matter because it’s synthetic. I don’t fully get the logic, down is not a good insulator by itself, it functions by lofting up and trapping air. The amount it lofts up is proportional to how effective it is, and sticking a heavy synthetic quilt on top of a down quilt just squishes some of that air layer and reduces its efficiency.
At a certain point of wetness, down bags just give up and collapse, and you wake freezing and shivering and in danger of hypothermia. There are plenty of reports in various hiking blogs about rough nights encountered after the collapse of a down bag. For example Maz goes through it here and Henrik has a go here, neither of them liked it much.
What I ended up doing (after a lot of playing around) was to use an extra layer, called a vapour-barrier layer (VBL). The idea is simple, you stick a waterproof layer between your repulsive clammy moist body and your delicate down quilt. The moisture can’t get to the quilt so it can’t collapse it. “Wait a moment!” you might well say, “surely that’s just like wearing a black plastic bag or something, won’t you get all disgusting and sweaty inside it?”. Bingo, that’s exactly what it’s like and exactly what happens. You get in your VBL and after an hour it’s like lying in a pool of your own stinking, goopy sweat. In fact it is lying in a pool of your own stinking, goopy sweat. Sexy!
That’s the idea at its most basic, some people advocate the idea that your skin also stops sweating after a while in a VBL, that after a certain saturation point your skin realises that sweating more is not a good idea and just gives up. This is bollocks as far as I can tell (I’m a terrible cynic, if it’s not on pubmed I consider it folklore). There’s no need to dress up the idea, it works even if I do continue to sweat all night and that’s OK with me, it’s OK with me because it works. I decided to use the Adventure Medical S.O.L. Thermal Bivvy Sack as a VBL. It’s a light, non-woven nylon space blanket, totally wind and waterproof. It has some velcro around the edges to stick it together, and comes in a tiny shitty stuff-sack. It weights around 220 grammes and costs around 300 SEK.
The Winter sleeping system
The ground layer is the ever reliable Exped downmat 7, big fat valves that don’t freeze up like the smaller twist-caps on thermarests, built in pump so you don’t get breath-vapour condensing inside the mat and screwing up the down. I’ve had a slow leak with my downmat during Summer, but a dunk in the bath revealed the hole, and a dot of rubber cement from the repair kit sealed it up. There’s a great set of instructions to read on repairing a hole here, courtesy of Exped. I think my girlfriend put the hole there to stop me from going camping. Or to trick me into having a bath.
It’s hard to hype the Exped downmats, they deservedly have a hell of a reputation. Super-insulating, incredibly comfortable, reliable, resilient and full of clever design details. They’re overkill for warmer weather, but I hate to buy things that I already own and have no intention of buying smaller lighter mats for Summer. As I use it all year round I designed my MYOG bivy-bag to fit the exped 7 exactly. The bivy-bag has been in use for months, but I still haven’t finished working on it.
The end of the footbox (and half the top) of the bivy-bag are made of a breathable 240 g/sqm material. Apparently it’s a bionic material, that opens its pores at warm temperatures and closes them at lower temperatures. Not totally sure how effective it is but will keep an eye on it. The rest of the top, sides and bottom are made of thinner, lighter non-breathable 90 g/sqm PU-coated nylon. All from extremtextile.de.
All the seams are tape-sealed on the inside, with extremtextil’s seam sealing tape.
When sewing the materials together, I placed one material over the other, folded them over and sewed that fold, so the seam holds the folded material in a sandwich, hopefully making it more waterproof than just flat sewing them together (demonstrated below). This seam probably has a name but I don’t know it.
The bathtub corners are also designed to be waterproof, instead of cutting the material and sewing it, I folded the edges together and sewed and seam-sealed them together at the top.
The zip is for entry-exit if the head of the bag ever gets finished, it’s a YKK waterproof zip from extremtextil. The material above the zip folds down over the zip partially, then the inside fold is sewn and taped, so water running down from above will not get near the seam, it will drip onto the zip. Then below the zip it’s the opposite, the material folds on the inside of the zip, which is taped on the outside so that water can’t get near that seam either. Looks a little uglier with the tape outside but looks aren’t important, as my mom used to tell me, what’s important is that as long as the water is mostly coming from above, it won’t even get near the sealed seams.
The hood of the bivy-bag is the last part to finish, it’s completely open at the moment. I’m just not sure what to do with it yet! It actually works pretty well as it is, but I will try and finish it up in a better way over Summer when bugs become a problem. Currently I just pull it over my head, it’s long enough that no weather gets in.
The hood, draped over the shovel.
All the layers visible in the photo below. Outer layer is the blue breathable bivy-bag top, then the Warhammer black mamba down quilt, then the VBL, and finally a green silk liner.
In the mornings the VBL and the silk inner are wet, so I turn the VBL inside out and hang them over ski poles. They are both thin and non-absorbent and so dry in minutes if the weather is OK.
Below is a look at all the components wrapped up. I have no stuff-sack for the bivy-bag as it’s not completed yet. The down quilt packs away easily. The VBL is impossible to get back in the miniscule stuff sack with icey fingers. The Exped downmat is a goddamn miracle of design for packing away. No matter how shitty the conditions have been, no matter how frozen and unresponsive my fingers have been, I have always been able to get it rolled up and in the bag in one go. I love the way it packs away.
Theoretically before hitting the sack I can eat all the extra strong lamb vindaloo I want, sweat like a priest in a kindergarten, and yet the down will be safe from all my nocturnal emissions. In the morning I splash my way out of the VBL, twirl the silk liner around to dry, invert the VBL and mop away the sweat-soup with an old sock. And in practice that’s exactly what happens. The interior of the VBL is soaked, but it absorbs nothing and dries in minutes if left to drip. The silk liner absorbs very little and also dries relatively quickly, while the sensitive down bag remains bone dry. On top of all that I wear the cold-avenger to bed as well. The cold avenger is a nice fleece lined balaclava and detachable mask for very cold weather. The mask part has this plastic cup and a little ventilation gizmo that mixes your warm exhaled air with incoming cold air so you don’t get cold in your lungs.
The best thing about the cold avenger is how it makes you look like some kind of ski-ninja.
I got it for skiing and robbing banks but tried sleeping in it once to see if it would help controlling exhaled moisture. This made a clear difference. Without it I wake to a halo of frozen condensation around my head, stalactites hanging from my nostril hair (especially when sleeping without a shelter). With it there is no sign of condensation around my head, inside the mask though it’s pretty drippy. I started wearing the ‘hat’ part of the cold-avenger to keep my head warm (down quilts only come up to the neck, forcing you to rely on your day-time head warming gear to keep your head warm at night), and then tried the mask on when I saw the only damp parts of my quilt were at the head end, so then i started wearing the rubber mask part too. If you want to adopt the mask idea then I hope you have as much S&M experience as Tomás ‘The spankinator’ has, because some prudes do find it a little hard to sleep in a rubber mask.
Inside the mouthpiece, wetter than a nun in a candle shop.
Is a VBL worth the hassle?
Yeah, totally worth it. Downsides do exist, you might find it uncomfortable to sleep in a moist environment. Whatever is with you inside the VBL will get wet. If you are the hardcore ultralighter who wears all of his clothes to bed as part of the sleeping system, then you’re going to wake up with a lot of wet clothes. On the other hand, there is no need to wear clothes in the VBL. The Adventure Medical bag retains an insane amount of heat, so it does more for warming you up than a jacket will do. A base-layer is all you need, and if you’re using synthetic or wool for base-layer, then it getting clammy isn’t such a big deal. I’ve found so far that the silk-liner prevents my base-layer from getting very wet, it usually dries during breakfast.
You also have the problem of dealing with a wet VBL and liner. This is not a real disadvantage, it’s a far simpler problem to solve than drying out a quilt. You can wipe them down and hang them outside in good weather and they are dry in minutes, literally. Your down bag remains bone-dry, totally pristine. Wake up in the morning, stuff it in the stuff-sack and rest easy that it will allow you to rest easy in another 12 hours.
With a down quilt the VBL is capable of dealing with proper cold, and maybe with just the VBL and a liner you could have a hell of a light Summer sleeping system. I’ve only tried the VBL in Winter, and some people say in Summer a VBL is too clammy and wet, but I will try it out anyway and see how it goes in a few months.
The Adventure Medical S.O.L. Thermal Bivvy Sack.
I don’t think you need to buy this thing to have a VBL, you could easily make one from recycled plastic shopping bags, you can buy a roll of extra-large black plastic bags and use them, you could use a diving suit, or a gimp suit, or you could be all fancy and make a MYOG VBL from siliconised nylon or something. It’s a stupidly simple thing to make, easily DIYable. The Adventure Medical bag is pretty good though, if you don’t mind the cash. First off, it’s silent. No plastic sounds as you roll around in it. Secondly it has a soft, textile feel to it, so it’s a lot less disgusting when wet than a plastic bag would be. Thirdly, it has the claim that it reflects 80% of radiant heat (a typical adult gives off around 100 watts in radiant energy).
The bag lends itself to modification, it’s massive, so there is a lot of leeway to cut weight by cutting the bag to fit your size and sewing it up a bit. And I promise you won’t feel bad taking a knife to it, there is no fit or finish to this thing. The sewing is laughable and the velcro around the edges is just ridiculous. It would be hard to do a worse job.
The picture below shows the shoddy sewing, a tear already on the right side, and also shows how the hook velcro patches tend to grip onto the inner fabric.
Downsides apart from the dodgy sewing are the insanely shitty stuff-sack, it has to be the worst stuff-sack ever. You need masterful origami skills to repack the bag into the stuff-sack, it takes ages to do, and that’s when you’re at home, indoors, warm and dry. Doing it in the snow is just impossible. I plan to cut it to fit me better and then perhaps it will fit a little easier into the sack. We’ll see. I would reiterate the fact that this fabric is damn nice for a waterproof material, so all of these downsides are irrelevant to me, it’s premium VBL material and plenty of it, so well worth the small price.
Anyway, that’s enough nerdy shit about VBLs. Trying VBLs was a bit like having an enema, at first it felt really wrong and a little disgusting but then it felt really great and I want everyone else to try it too. Go and try it!