Vapour barrier liner socks or VBL Socks (or just VB) are often seen as being some strange and obscure technique use solely for use by those at the very extreme end of adventure, primarily people working or climbing in the Arctic or Antarctic. In fact VB socks offer a lot to anyone operating in sub zero temperatures for extended periods of time, especially on multi day routes - with the longer and colder the route the more they become applicable.
What do VB socks do?
Wet socks caused by sweat are a prime cause of cold feet and worst still frostbite, with sweat build up on a long hard walk-in often leaving socks soaking, causing cold numb feet on long winter belays. On long multi day routes socks get both progressively wet and dirty (one of the most important skills an alpine climber can have is how to rotate and dry socks while on a long route), and a bad night where you can’t change socks (say you are forced to sleep with your boots on), can have serious consequence the following day if your socks are soaked with sweat and your boots are thin. A VB Sock blocks sweat from entering your socks and wetting them out, which means you can wear one pair of socks for days, even months without then ever having to be dried or even cleaned (not getting dirty means they retain their loft much longer).
If you wear leather boots then VP socks are even more effective as they also block sweat from entering your boots insulation, which tends not to be so good at multi day use without drying.
Don’t your feet get sweaty?
When you trap all the sweat in your sock you would imagine it would build up and build up until they overflowed with sweat. In-fact what happens is that when you get 100% humidity within the sock your feet stop sweating. I’ve worn a pair of socks for over 36 hours and when it came to take them off my skin was simply as damp as if I’d worn them for only 5.
What kind of VP to use?
VP socks have been made from nylon and neoprene, with commercial models made by RBH Designs, PHD, Exped and Integral Designs, but perhaps the best sock of all can be made using the humble plastic shopping bag. Using the very thin gauge plastic bags you get a checkouts (not the heavy duty ones) give you a disposable option that will last about a week, which is better than a nylon one as they do get pretty manky inside with dead skin etc. Being very thin plastic also means that seams are not a problem, plus if they ruck up a little they shouldn’t cause blisters.
Are they uncomfortable
Are VP socks as comfortable as wearing a nice pair of wool socks next to your skin? Well no, they can feel a bit strange at first, but even though they can feel a little icky, they feel a dam sight better then frozen feet, with feed feeling damp but warm, instead of so cold your can’t tell if they’re wet or dry.
There are two basis ways of wearing a VB sock, one is next to the skin and the other is over a thin sock, probably a synthetic one (so that it dries fast). A liner sock will take a bit of the nastyness of wearing a sweaty layer of plastic next to your skin, but in my mind is inferior to a next to the skin system, as this layer traps more sweat (you sweat more), adds a damp layer next to your skin, and is something else to dry. Also long term you end of with socks that unless you can replace them every few days, will stink of ammonia and could lead to foot problem. A damp foot on the other hand can be dried in seconds and the VB sock just replaced when it gets too stinky. Some also wear a VB sock over the top of their thick socks, but this is only when wearing boots that have wool liners/boot inners.
It’s a no brainer that you need to keep your toe nails in check, making sure they are cut short and free from anything that could damage the socks. I would also make sure you go through a few weeks of scrubbing away the dead skin before a big trip, as wearing VB socks is a bit like heaving some heavy duty foot spar treatment, with a great deal of dead skin coming off each day (wear VB socks for a few weeks and your feet will look as good as new!).
After wearing the VB socks all day remove them and turn them inside out, allowing the sweat to freeze so you can shake it off. Give your feet a rub with some toilet roll, or just allow them to dry, and then stick some anti-fungal talk on them to both further dry them, make then smell nice and keep foot rot away. That done you can stick your wool socks back on to sleep in (sleeping will not make the socks damp). In the morning stick your VB socks back on and away you go.
As I said in my intro the length of time you spend out, coupled with how vital it is that you maintain high loft in your socks is the deciding factors on how crucial using a VB sock is. If you have super warm boots or it’s not too cold them wet socks is not a problem, but get wet socks and leave them wet in your sleeping bag, then stuff them in frozen leather boots on day two and you may have a problem. On the other hand if you’re skiing for 100 day to the South Pole and back, and have soft boots and only two pairs of socks then VB socks are the only way to go, and the same applies on any high mountain trip (Denali, Ama Dablam, Mont Blanc even). VB socks really come into their own when wearing leather boots as your socks tend to play a much bigger part in staying warm, so keeping them dry will allow you to be safer (cold and frozen foot are a distraction and will have a big knock on effect) and just be happier on the hill.