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Adding insulation to bag footbox w/o modification?
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Craig Burton

Locale: Smoky Mountains
Adding insulation to bag footbox w/o modification? on 07/27/2008 19:33:48 MDT Print View

I'm beginning to prepare my winter gearlist, and I think I am almost finished -- with the exception of extremity insulation for sleeping.

I'm considering the PossumDown gloves for hand insulation (if they ever come back in stock); but hand insulation isn't a major concern since I can easily warm my hands with different sleeping positions.

For my feet, however, I'm what you might call a "freezing" sleeper in that area. I've tried various bags with little success in warming my feet; and I've even tried 4-layers of varying thickness wool socks which provided only marginal warmth! Looking back, this method probably didn't work so well because it restricted the blood flow so much.

I plan on purchasing PossdumDown socks and/or down booties; but I also plan on pursuing alternatives if those don't work out.

I've tried placing my footbox in my pack with great success, but the constriction bothered me -- and sometimes this also isn't feasible in some situations (ie. wet pack). With that said, I figure an external footbox is the way to go since it has worked in the past and it is a lot easier to fix when my feet inevitably slip out.

So I ask, what is a good solution for this dilemma I have here? I haven't seen any products available, and I don't want to add on too much extra weight and/or inconvenience of an interior vapor barrier or heavier bag. Would a garbage liner along the outside work? Just throwing that out there -- I don't want to have to make any modifications to my bag because there's about a 99% chance I screw it up.

PS. the temps I am concerned about are the high-20s to mid-30s, and, no, I don't use a bivy (tenter here).

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Adding insulation to bag footbox w/o modification? on 07/27/2008 19:43:49 MDT Print View

Given the temperature range of 'high-20s to mid-30s' you are talking about, my answer is very simple. I suspect you are letting your head get cold. You need to either use a padded hood or some other good insulation over your head.

If you haven't kept your head warm, no matter what you insulation you put around your feet, it won't MAKE them warm. Make your head warm and more warm blood will then flow to your feet. A simple pair of fluffy socks will then be more than enough.


Craig Burton

Locale: Smoky Mountains
Re: Re: Adding insulation to bag footbox w/o modification? on 07/27/2008 19:56:04 MDT Print View

Thanks Roger; I never thought of that, and it could very well be my problem.

I usually wore my Polartec beanie to sleep with me, and I was quite warm in the head and face; but that could very well just mean I was just losing a lot of heat from the area. I never tried wearing my balaclava to sleep with me, but I will give that a try (in addition to my beanie) when the cooler weather starts to roll in... eventually. I hope it works as easily as you suggest.

Ashley Brown
(ashleyb) - F
Re: Adding insulation to bag footbox w/o modification? on 07/27/2008 19:56:30 MDT Print View

Being a cold feet person myself I have two tips to offer. Firstly, do not go to bed with cold feet because they will take hours to warm up. Secondly, you are often better off adding more insulation to your core and head area than to your feet.

It took me a while to appreciate that I could make my feet warmer by adding insulation to my core/head rather than directly to my feet. It makes sense though, because insulation does not produce heat, it just helps keep in the heat that has already been produced. If you get extremely cold feet (like me) then your feet are probably not producing enough heat because there is not enough blood flowing around them. This happens when the body restricts blood flow to the extremeties in order to keep the core and head warm.

So... even if you feel your core/head is "warm enough", you should still add more insulation to this area in order to warm your feet up. You can try it at home and see how quickly the effect works. Once you add extra core insulation you get toasty warm and blood flows to your feet freely once more.... resulting in nice warm feet. I find that once my feet are warm in my sleeping bag I don't have much problem keeping them warm for the rest of the night.

If you want to achieve this effect without adding much weight, then extra head insulation is your best bet. If you have a down jacket with you then definitely wear it. The other alternative is to do some vigorous exercise immediately before you get into bed. Do it until you feel yourself getting hot under your clothes, and then hop into your sleeping bag.

Works for me, so try it if you haven't already. You can also wear a liner sock, followed by a plastic bag, followed by a thicker (loose fitting) sock. The plastic bag acts as a vapor barrier and will keep your feet warmer. The main thing is though, the heat has to be in your feet to begin with in order for the extra insulation to work... and heat only comes from blood flow (or a hot water bottle, which is another idea you make like to try).

Edited by ashleyb on 07/27/2008 19:58:35 MDT.

Ashley Brown
(ashleyb) - F
Re: Re: Adding insulation to bag footbox w/o modification? on 07/27/2008 19:57:41 MDT Print View

Roger beat me to it...!

Ross Bleakney
(rossbleakney) - MLife

Locale: Cascades
Warmer Feet on 07/28/2008 12:09:47 MDT Print View

Warming your head is the first step to take. But if it turns out that your feet are unusually cold anyway, you might try a second set of socks in the largest size available (to go over your regular socks). If that doesn't cut it, you might try getting lightweight booties. Unfortunately, the lightest ones I've been able to find are still a bit too heavy (in my opinion) because they often have durable bottoms. I've been tempted to make my own. At a minimum, making toe cozies looks fairly simple and doesn't weigh much at all:

Edited by rossbleakney on 07/28/2008 12:10:29 MDT.

Diplomatic Mike

Locale: Under a bush in Scotland
Adding insulation to footbox on 07/28/2008 13:00:57 MDT Print View

I agree that the best way to warm your feet, is to wear a hat. I often hike with friends though, and we like to sit up talking and sharing a wee dram now and again. ;) Then i like to wear my Feathered Friends Down Booties. They have an Epic removable outer, and around 4oz down in the inner. Mine weigh 9.7 oz/276g total. The inner weighs 4.6 oz/130g. They are amazingly warm and pack down to nothing. Just carry the inners if you're hitting the bag after walking.

Neil Bender
(nebender) - F
Re: Adding insulation to bag footbox w/o modification? on 07/28/2008 13:17:21 MDT Print View

Depending on your stove/fuel/water situation one useful technique is to heat a bottle of water to slightly cooler than boiling and toss that into your bag at the feet. That way your feet's warmth and circulation gets kick started by an external source of warmth and you will have liquid water that isn't frozen to consume or cook with in the morning. Just make sure you use a container you know won't leak or otherwise fail.

Similarly if you use a pee bottle so you don't have to exit the tent , that warmth can also be captured for a while by keeping the bottle in your bag.

Extra ground insulation in that area might also help. Anything to put the balance of heat loss to be lower than heat production is worth trying.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Adding insulation to bag footbox w/o modification? on 07/28/2008 15:44:18 MDT Print View

> Extra ground insulation in that area might also help.
Neil is 100% right.

Jack H.
(Found) - F

Locale: Sacramento, CA
foot insulation on 07/28/2008 18:07:52 MDT Print View

Here are some ideas:

- if you're only out for shorter trips, a great solution are chemical foot warmers. I spend a ton of nights out winter camping and they're the best solution for people with chronically cold feet.

- Montbell bags have a feature where you can turn the footbox of your bag back in on itself, which creates a sort of foot pillow. You could simulate this with a down vest or jacket stuffed in your footbox. It works VERY well. You need another puffy item to put down there though.

Ashley Brown
(ashleyb) - F
Re: Re: Adding insulation to bag footbox w/o modification? on 07/28/2008 18:30:21 MDT Print View

"That way your feet's warmth and circulation gets kick started by an external source of warmth"

This is another very good point. If you get into bed with feet that are icy to the touch it can be extremely difficult to warm them up (if you have poor circulation like me). Even adding a lot more insulation to the torso or head (so that I feel very warm) can still leave me with cold feet.

The only way to get my feet warm in this situation is to, as Neil said, kick start the circulation. I don't often have a hot water bottle, so instead I take off my socks and place my feet up against the warmer parts of my leg (behind the thigh/knee... obviously only one foot at a time). This doesn't make my feet warm, but it increases the circulation enough that the extra torso/head insulation is able to have maximum effect. Once my feet are warm I don't need much extra foot insulation other than some warm socks.

Clearly the best way is to not let your feet get cold in the first place. It's always easier to maintain warmth rather than try and warm something up that has become cold.

Jack's suggestion of chemical heat warmers is a very good one too. A temporary external heat source plus proper head/torso insulation and you can't help but get warm feet!