Double layer felt liners?

[jamieS]

It seems like there are two major approaches to deep cold footwear: double wool socks inside a felt liner and a wool sock in double felt liners. I stumbled on the former approach on the Lure of the North website and I met someone earlier this month that uses the latter for his near-arctic-circle trips (size 10 feet, size 11 liner inside a size 15wide liner!).

It raised a question for me: At what temperatures does a double sock/double felt liner become necessary/appropriate? (Steiger seems to say a thick wool sock in a 9mm felt liner (with appropriate insoles) is good to about -30/-40dF?)

Any experience with double sock/double felt liner footwear systems? What would be your temperature cut-off for a single sock/liner versus double sock/liner system?

[Justin P.]

I've never tried a double liner.
But double sock in a single liner with a felt insole gives me a double liner on the sole portion only.
I've worn that at -30F walking and been comfortable, but not hot footed.
I've probably only ever seen -40 a couple times in my entire life.
But it won't work well if your double socks are tight or if your boots are tight.

I don't find it particularly difficult to stay comfortable at -30 F if I'm moving and if it's not windy.
Wind and inactivity complicate matters and change everything real quick for me though, that's when I start to have to really fight back to win against the cold.
I'm not convinced my feet will ever be truly warm at -30 just sitting for extended periods.

The felt insole are always in my muks. I suppose I probably start double socking at around -20
In the teens and sneaking around zero I still often wear Muck boots, but those have felt insoles too.
And my insulated hip boots also have felt insoles.
So, I'm a felt insole fan, I guess.

[Undersky]

Hey JamieS! Glad you are talking about cold weather 'cause maybe that means we'll get lots of it this winter. Supposed to be -31C here by Tuesday (-23 or 24F), so we're getting closer!!

My experience echos what Justin P has said. I might add just a few things if I may.

First, firm-soled footwear like Mucks or Sorels support the foot sole really well - well enough that my foot does not flex much and the muscles that support my foot and ankle don't have to work much. The result is comparatively cold feet. Wearing the same insulation in Stegers or any other soft-soled mukluk will feel much warmer to me because my foot flexes a lot more (assuming I am walking or snowshoeing) and this seems to allow (or to force?) more blood flow. More blood flow = more heat to the feet 'cause in the cold temps you are talking about I really need to push warmed blood from well insulated and hard working major muscle groups out to my feet - for my feet aren't producing enough heat on their own!

Second, as Justin P states, activity changes everything. So double pr of thick wool socks inside 9mm liners with a thick insole under my foot is going to give a hot foot if I am pulling a sled through soft snow (assuming I'm well hydrated, well rested, well fed, and the rest of my body is well insulated). The second hour of sitting still becomes too uncomfortable even if I am moving my toes around.

Moisture is a killer for me. In my sorel-type boots with rubber soles and rands, and only partially breathable uppers, my feet often get too warm, and little damp. A few hours later in -30 to -40s that moisture has built-up enough so the boots start to feel clammy even if I keep active. Then it is just a matter of time until my feet are in a chilling, downward spiral. Conversely, in a fully breathable mukuk, using liners and insoles that have no impermeable layers (like the almost ubiquitous perforated silver film 'radiant barrier' lining) elevated moisture levels are far far less of a problem. My feet stay warmer much longer.

Lastly, all of this keeping warm business has shifted as I have gotten older and become less fit. Greater years combined with lesser fitness equals greater need for insulation for me. Not a crazy difference yet, but definitely a noticeable difference!

Still, I raise a toast to cold weather! Bring it on!

Specifically, in a pr of moose hide mukluks, a 9mm wool felt insole, a 9 mm wool felt liner, a very thick wool sock with no elastic on the calf, and a medium weight wool sock next to the skin is good for me for the coldest temperatures, so long as I maintain some activity and keep the rest of me warm.

[Justin P.]

Undersky, you bring up and interesting point about foot flexing. I never thought about it that way, but it makes perfect sense.

Getting older is another good point. When I was young I worked outside more than now, so I was more acclimated to the cold. I don't notice it so much when I'm active outside, but man do I sleep colder now than I ever have in my life. 15-20 years ago I could've never tolerated the insulation levels I now sleep in. I would've burned right up.

[jamieS]

Undersky and Justin, this is a really helpful conversation. I think I'm stumbling toward an approach based on what you are saying... I think I'm going to stick with the more basic one-or-two socks and a single liner, at least for now. (With felt insoles.)

The more I thought about what you were saying, the more I realized that it's much easier to pack and dry out a thick sock rather than a second liner. Plus it's easier to mix and match to fit the temperature. Might not be the warmest set up, but I'm also not going to the arctic circle anytime soon...

The point about never being warm at -30dF just sitting around was an important point. I agree. I get really cold feet standing still, but so far my best solution is standing on a foam mat as a way to bump up the insulation. I also tend to get hot/sweaty feet while moving and so wearing two liners is probably going to be too hot while moving...

Anyway, now I'm feeling better about my current set up... and I'm eagerly awaiting deep winter!