LNT Canada is a national non-profit organization dedicated to promoting responsible outdoor recreation through education, research and partnerships.

You are not logged in. Would you like to login or register?

11/20/2017 10:45 am  #1

'Emergency blankets', reflective foil and plastic bags ..

Back in mid-September of 2001 I was camping on Little Island Lake. The evening sky had gone crystal clear and I knew the already cold temperature would plummet overnight. In anticipation of that, I placed an empty large black plastic bag alongside my sleeping-bag. Sure enough, in the middle of the night I woke up with very cold feet. By slipping the plastic bag around the outside of the bottom of my sleeping-bag, I was able to retain enough heat to comfortably get back to sleep. I knew that the bag would also trap my transpired moisture, rendering that part of my sleeping-bag somewhat moist. Since it was my trip's last night, that wasn't an issue, but would have required some forced drying of that end of the bag if I'd needed it another night.

A few years ago I was camping on McKaskill Lake in early June when the freezing night-time temp woke me up. I laid an 'emergency blanket' over my sleeping-bag to retain body heat. While it worked fine, I had to dry-off the sleeping bag the next morning since trapped transpired moisture had wet its outside. Another side-effect was that the emergency blanket's initial "crinkly" noise disturbed my buddy who was in his nearby tent .. also woken-up by the cold and trying to get back to sleep!

I'm wondering if anyone has come across a thin product that combines some of the reflective quality of "foil" with some degree of "breathability"? Maybe a perforated foil layer attached to a soft fabric .. somewhat warming, still dry and next-to-silent?


11/20/2017 10:59 am  #2

Re: 'Emergency blankets', reflective foil and plastic bags ..

Are you looking for something just to cover your feet area?  I get cold feet as well so I try to sleep with an extra thick pair of socks on.  I also put my clothing that I want to wear in the morning in the bottom of my sleeping bag.  It serves threepurposes:  1. it fills empty space in the sleeping bag making it easier to heat and keep warm, 2. it makes putting on fresh clothes in the morning not so unbearable (nothing like putting on a freezing cold shirt when it's -25 lol), 3. it allows me to put my feet under the clothing items at the bottom of the bag if my feet get cold.  

Is your sleeping bag down?  Like you say, you don't want to introduce any more moisture into a down bag than needed...inevitably your down bag will get colder and colder over a longer trip unless you are able to totally dry it out during the day (many down bags are black on the inside allowing you to turn it inside out to dry off quicker).  I'd be reluctant to put anything that traps moisture on top of my down bag for an extended period of time


11/20/2017 11:22 am  #3

Re: 'Emergency blankets', reflective foil and plastic bags ..

What I'm after is a means of adding to my 'summer-bag', enough added warmth to handle the unexpected cold-snaps of late spring and early fall. The moisture retention problem is the real problem.

After making my original posting, I did a google search for 'soft silent dry foil thermal blanket" and came up with a "Thermartex" product from England .. http://www.backpackinglight.co.uk/practical/XA107.html  .

"Measuring approximately 1.6m x 2m and weighing only 200g the aluminized woven rip-stop nylon blanket is highly breathable and reflects up to 75% of radiated body heat."


It's not cheap .. 46 pounds UK (pushing $80 CAD) .. not to mention shipping, etc.!

Has anyone come across a more economical North American equivalent product?


     Thread Starter

11/20/2017 12:28 pm  #4

Re: 'Emergency blankets', reflective foil and plastic bags ..

Why not an inside liner Barry?


11/20/2017 12:37 pm  #5

Re: 'Emergency blankets', reflective foil and plastic bags ..

A light weight breathable bivy could possibly fill the void as well.  SOL make a few models that may fit the bill without being too expensive or taking up too much space.



11/20/2017 1:05 pm  #6

Re: 'Emergency blankets', reflective foil and plastic bags ..

Hi Barry,

You did not mention which emergency blanket you have, but one piece of gear I've really been impressed with is the All Weather Emergency Blanket sold by MEC for $18:


The blanket is reasonably light at 285 grams. I've used it under sleeping bags on cold nights to provide effective additional warmth and never noticed any dampness in the morning. It doesn't make much noise to my ears. It's also versatile: I've used it as a durable tarp in a downpour. One con is that it can be a bit bulky to pack, but if you use it as an inside liner for your pack that's not too much of an issue. Hey, it's cheap enough that even if it doesn't fit the bill you haven't lost too much.



11/20/2017 1:23 pm  #7

Re: 'Emergency blankets', reflective foil and plastic bags ..

IBGPIN wrote:

A light weight breathable bivy could possibly fill the void as well.  SOL make a few models that may fit the bill without being too expensive or taking up too much space.


Thats what I was thinking. Lots of choices. I have read reports of these working well..Weighs 6.5 ozs.


Last edited by ShawnD (11/20/2017 1:24 pm)


11/20/2017 1:24 pm  #8

Re: 'Emergency blankets', reflective foil and plastic bags ..

Hi Barry,
I have added a home made lamb skin fleece inner liner to my down sleeping bag ( it's old). I purchased the material at $15.00/meter.  ( on sale, normally $20.00/m). 2 meters necessary, its wide enough to double up  and contain a person size xl.. Sow along length and bottom. 2 metres is enough to have the top fold over the edge of your sleeping bag.It's extremely light, holds warmth great, stuffs into a compression sack  to about the size of small loaf of bread. It breaths great, no condensation. I used it this September and loved it. It weighs around a pound.
One tip: It MUST be lambskin fleece, as all other fleeces are either too heavy, thick,dense, or too light. Any material store worth its salt should have it.
It's also warm enough on its own for summer camping.


11/20/2017 3:07 pm  #9

Re: 'Emergency blankets', reflective foil and plastic bags ..

Thanks for these suggestions. Any and all suggestions are appreciated. Keeping the bulk down is a priority for portaging. Please keep ideas coming!

     Thread Starter

11/20/2017 3:48 pm  #10

Re: 'Emergency blankets', reflective foil and plastic bags ..


11/20/2017 4:07 pm  #11

Re: 'Emergency blankets', reflective foil and plastic bags ..

Tyvek (House wrap) is a water resistant, breathable material as well that can be made into a cheap bivy or even partial cover for your sleeping bag as well as other items, Tarps, ground sheet etc.
I currently use it as a ground sheet, but have been scheming on making a few items with it as I have some leftovers from a house build..
Google Tyvek Bivy for some reading.
I read washing the tyvek first,  softens and quiets it considerably but still keeps its original water shedding breathable properties.


11/20/2017 4:57 pm  #12

Re: 'Emergency blankets', reflective foil and plastic bags ..

I have an Aluminized Tyvek Bivy. Bought it from 2GoSystems. They don't make the version I have any more. It looks like the SOL Escape Bivy is also made of Aluminized Tyvek. Much better then the throw away SOL Survival Bivy. Basically this is a breathable overbag with a silver lining. Pretty tough material. The crinkling and stiffness goes away with use. You can just throw it in the washing machine to soften it up. Don't put it in the dryer. It will melt.

I use the Bivy cold camping, -10 or colder, primarily to keep snow, snowfleas, water, dirt of my sleeping bag. Or, hot tenting for the same reason. It does provide some insulation but I mostly use it to keep my stuff clean and dry. In cold temperatures and canvas hot tents where humidity levels are low condensation is not an issue. But in at +/- 0 degrees in fall and spring (high relative humidity) my experience is a film of condensation occurs on the inside of the bag and this transfers to your sleeping bag

I would get a better bag. Maybe a really good/warm down quilt. You can regulate heat in a quilt so much better than a bag. Otherwise, I would suggest a bag liner. Sea-to-Summit Thermolite bag liners are really good. People just assume they don't work because they are so thin. They do work! Shimmie out of one for a bathroom break in the middle of the night and you can immediately feel how much insulation they are adding to your bag. Just wish they had a zipper. They are awkward to get in and out.

Last edited by MartinG (11/20/2017 4:59 pm)


11/20/2017 5:02 pm  #13

Re: 'Emergency blankets', reflective foil and plastic bags ..


LOL. I just picked up a pair of these.

Only 4 ozs. Toasty feet !!!



11/20/2017 9:58 pm  #14

Re: 'Emergency blankets', reflective foil and plastic bags ..

I'm with Shawn on the liner. I made a fleece liner for my -7C North Face Blue Kazoo.  It's near 20 years old and still served me well last Family Day weekend in the interior. The liner is simply a fleece banket sewn up 3/4. When it gets really cold I also dawn the Mec  down booties and have been known to use adhesive toe warmers in a jam. Anything that retains moisture is a bad idea IMO.

Last edited by Shayne74 (11/20/2017 10:58 pm)


11/21/2017 9:01 am  #15

Re: 'Emergency blankets', reflective foil and plastic bags ..

We use fleece liners too. My unscientific but comfortable sleeping estimate is that they add about 5C of warmth to a sleeping bag. There is a picture of a couple at the bottom of this page:



11/22/2017 3:34 pm  #16

Re: 'Emergency blankets', reflective foil and plastic bags ..

I think a light weight fleece blanket works the best. I've tried the emergency blankets and they don't work well for someone of my build(tall but thin). The blanket is light and will absorb any condensation generated throughout the night, I stuff mine inside my sleeping bag before packing the bag up when leaving for my trips. I won't go on a spring/fall trip without one now. The added bonus is you don't have to listen to the "turkey" turning over in the middle of the night! (that's what I call my buddy when he uses an emergency blanket *crinkle,crinkle*)


11/24/2017 2:33 am  #17

Re: 'Emergency blankets', reflective foil and plastic bags ..

Personally, I'd go with more down.  Either a throw or a vest zipped around the bottom of the bag.  The idea of adding clothes to the bottom of the bag to limit the amount of air your feet need to heat makes sense.  You can also squeeze all the warm moisture laden air out of your bag right when you get out of it to get a jump on the drying process.  Another option is to stash a couple of "Hot Paws" or similar somewhere in your kit.


Board footera