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Suzzz
08-18-2007, 22:56
Does anyone know the R-value of Space Blankets? I'm not talking about the small ones you find in first aid kits, I mean the thicker, sturdier ones. I wonder if they would insulated well enough if put under the sleeping pad and above the sleeping bag. They're light and small to pack. Would it be possible to get away with a smaller lighter sleeping bag by using one?

7Sisters
08-18-2007, 23:27
I woulld not rely on a space blanket for significant amount of additional warmth versus a proplerly rated sleeping bag because of the efficiency. If you use a space blanket, it will be very difficult to prevent significant heat loss wherever there are openings.

What time of the year are you planning and where are you going?

Frolicking Dinosaurs
08-18-2007, 23:43
The problem with space blankets is they don't breath so the moisture from your body ends up making your sleeping bag damp which makes it cold / less efficient. Also, the shiny coating of space blankets tends to delaminate rather quickly with regular use. While I carry one as an emergency covering for day hiking, I certainly wouldn't count on it to keep me comfortable. They will help ward off hypothermia, but they do not actually keep you warm enough to comfortably sleep.

Doughnut
08-19-2007, 10:16
I agree with Dinosaur, I used one for years in the military, sleeping on top of it, as a ground cloth, They do not wick moisture away, so your bag will be damp in the morning, However, on cold nights, it's like sleeping on top of an electric blanket

superman
08-19-2007, 11:36
Are you talking about those aluminum looking things or the ones that are advertised as emergency sleeping bags ($20 to $30)?

SGT Rock
08-19-2007, 11:43
Does anyone know the R-value of Space Blankets? I'm not talking about the small ones you find in first aid kits, I mean the thicker, sturdier ones. I wonder if they would insulated well enough if put under the sleeping pad and above the sleeping bag. They're light and small to pack. Would it be possible to get away with a smaller lighter sleeping bag by using one?
Their R-Value is based on application. The way you are planning to use them gives them almost no R-Value. They work best when there is nothing at all between the heat source and the blanket - they should be next to skin to actually work because they reflect IR heat - anything that blocks IR (like clothing, sleeping bags, pads, etc) reduces your IR heat signature, so for each layer, between you and it, you are reducing the type of heat loss it is designed to repell. At the point you are planning to put it, the only thing it serves as is a vapor barrier, and you could use tyvek for that.

smokymtnsteve
08-19-2007, 12:30
tyvek breaths so it is more of a wind barrier than a VBL.

SGT Rock
08-19-2007, 12:35
Well it is used as a VBL on houses, so yes I agree it breathes, but it still would work for a VBL since a material with a perm rating of 1 or less is considered a vapor barrier.

As for wind, I doubt any wind is coming from under the pad in a ground application.

Crazy Larry #1
08-19-2007, 12:41
Does anyone know the R-value of Space Blankets? I'm not talking about the small ones you find in first aid kits, I mean the thicker, sturdier ones. I wonder if they would insulated well enough if put under the sleeping pad and above the sleeping bag. They're light and small to pack. Would it be possible to get away with a smaller lighter sleeping bag by using one?
yep....................

Suzzz
08-19-2007, 17:02
Only wanderer, you're a man of a few words.

Thanks for all your opinions guys. I'll probably be going on an over-nighter this weekend. I'll probably try it and see for myself. If I get too cold, I'll be able to go to the car get the "real gear" as it will be close by. Nights are getting pretty cool up here in Canada, it's a good time to be trying new things.

JAK
08-19-2007, 18:27
The weight of a space blanket isn't insignificant, and you have to consider putting that weight into beefing up the rest of your system, rather than adding a layer. Even when I go minimal in summer I think a space blanket would be redundant with what I already bring.

For example;

#1. ground pad (minimal 1/4" full length)
#2. skin layer clothes - (top and bottom incl. head and socks)
#3. wind layer clothes - (top and bottom light as possible)
#4. sleeping bag or equivalent
#5. bivy sack or equivalent (optional) (possibly integrated with #1)
#6. rain Poncho/Tarp or equivalent

A space blanket might be most useful as item 5, since the other layers likely already exist in some form, but the weight might be put to better use upgrading one or more of the other layers, or a better solution for item 5.

A common situation in summer is I look at options for leaving my sleeping bag and gortex bivy bag home, without having to build a proper summer system. A poncho liner doesn't work for me because my poncho is my tarp. The summer nights here are potentially cool, and almost always 100% humidity once it cools down; so even mid summer I always have a full length for #1,#2,#3, and #6. But there might be a situation where it is warm enough, though damp, that all I need might only need a space blanket instead of #4 & #5 combined. Perhaps I will try this and see, but I think I would be better off with a second set of skin layers under my wind layers rather than a space blanket. Also I might be inclined to try tyvek, pretaped to my ground pad on one side and at the feet. Then perhaps a light wool or fleece poncho instead of the second skin layer. In summer a pair of plaid flannel boxers can serve as hiking shorts, worn alone or under or over the skin layer, or as a beanie, even as a towel until they get too fausty. Works for me.

Crazy Larry #1
08-20-2007, 08:14
That space blanket don't weight diddly woo woo, I have one that i use with my Kiva that has no floor in it. The blanket is my ground cover.........and on occasion on a very cold night in the winter time I have used for a wind blocker and added warmth.......

JAK
08-20-2007, 09:18
I don't use a ground cover. Seems redundant to me if you have a ground pad. A 1/4" 20"x72" pad cost $3 at the dollar store and also weighs diddly woo woo, or diddly woo woo woo in metric. The difference is the foam pad actually counts for something. Before I would add a space blanket I would make my pad thicker or wider. I've always gone 3/8", though I've been eyeing those $3 pads for summer. Perhaps it depends on how cold and wet the ground is. I suppose the right ground might act like a ground pad with just a thin layer over it. Up here you need a ground pad though, even in summer.

sarbar
08-20-2007, 09:26
I am working on a prototype for my tent for cold weather use, using the fabric I use in my bag cozies (it is a lined mylar fabric). It is durable and washable. I hate cold floors, and in winter it is a real issue with losing heat. Ok, I get cold in the mountains even in August......so I am trying it out this weekend. If it works I will be posting photos and how-to's.

JAK
08-20-2007, 09:52
They are definitely very packable, and very useful if you bring nothing else. Their marginal usefulness declines as you bring more other stuff though. That's my point. Such is the nature of radiant reflectors and vapour barriers. Once your covered, your covered, then what you really need is insulation and food. Still, I think I should shut up now and go buy one, along with one of those $3 pads, and do some back yard camping. Cheers.

IdahoDavid
08-20-2007, 17:55
I have used a space blanket in combination with small bungees to sling my sleeping pad under my hammock for extra insulation. I've since started using a better hammock. I do think space blankets ae pretty decent ground cloths, but under the sleeping pad. Never in contact with the sleeping bag.

smokymtnsteve
08-22-2007, 17:27
Well it is used as a VBL on houses, so yes I agree it breathes, but it still would work for a VBL since a material with a perm rating of 1 or less is considered a vapor barrier.

As for wind, I doubt any wind is coming from under the pad in a ground application.


tyvek is used as wind barrier on outside of the insulation of house ...6 mil visquene is used on the warm side of a house as VBL.

now as far as wind under a sleeping bag...maybe the shelter floors have gotten better since I've been down thataway,,,and then you got the hammock guys;)

Peaks
08-22-2007, 17:43
I don't know what the R value is, but I do carry a space blanket with me when peak bagging in winter, just in case.