In an article, Doug mentioned that emergency/space blankets have some basic problems with them. What might those problems be?

Thanks

My major issue with them is that they are not water permeable. If you sleep with your head under the covers, you end up with all your breath condensing on the side _you're_ on, and it drips on you, your bedclothes, whatever. You breathe out a _lot_ of water vapor.

On the other hand, they work. I've camped when it turned out my sleeping bag wasn't warm enough, and the space blanket made the difference between being able to stay warm or not being warm and having to leave. I wouldn't want the space blanket to be my sole source of warmth, but it works.

Phil

You may wan't to look into this topic. It seems, that although they have some flaws, they are quite usable.

Basically they dont have much insulating factor most say. But here is the upside of them
-lightweight
-reflective for heat loss prevention as well as signaling
-cheap shelter/poncho
-groundcloth use
-could be fashioned into about anything ie armsling, shelter,poncho,tarp etc.....

For anyone who questions their usefulness, stop by any of the medical tents during the Boston Marathon.

They work mainly by trapping air, rather than by reflecting heat. As such, a space bag is usually warmer than a space blanket because there are fewer ways for your warm air to get blown away. A large plastic bag is usually as good as a space bag, and can be much cheaper.

They're called Space Blankets because the material was first used in laminate space suits. One layer of the material will optimally reflect 90% of base body heat. The second layer reflects 90% of the escaping 10% and so on- in the controlled hermetic environment of a space vehicle. It makes you want to reach for a Hudson's Bay 5 striper and teddybear doesn't it <img src="/images/graemlins/grin.gif" alt="" /> The unit's strength is in portability. We are more likely to 'warm' to the idea of slipping a sealed unit into a pocket than that big old Hudson. The weakness is the simplistic hype from pop culture showing a avalanche victim deploying one and start working on their tan. They come into their own building emergency shelters. Draping one over your framework makes an excellent reflector to retain heat from a fire and bringing a little order to all the leaves, bark slabs, spiders, rattlesnakes,coyotes and pinecones you start piling on top. Survival illustrations always show an elegant geometrically perfect shelter. Mine look like a Foster's Freeze jumbo vanilla in 100 degree weather <img src="/images/graemlins/mad.gif" alt="" />

If you have ever taken one out of the package and played with it you will see the issues it has. It is smallish, tears easily, and is very noisy. It is hard to make a good shelter out of one. There seems to be some controversy as to whether they really reflect heat any better than a plain plastic sheet of the same dimensions. You really need duct tape on the corners to make a shelter. Their main benefit here in Arizona is they can be rigged to provide shade. I replaced mine with a clear 80”x52” trash bag from Survival and Outdoor Safety.

I can hop in it and pull it over my head for protection from wind, rain, or snow. I can fill it with pine needles, leaves, and grass and use it as a blanket. I can put it over a tree branch for transpiration. I can use it as a pup tent or tube tent. I can use it as a ground cloth. If a trash bag is good, a bigger trash bag is better!

I am still not settled on what to carry for shelter. I have a HD Space Blanket, small Space Blanket, two 60 gallon clear trash bags, and the 80”x52” clear trash bag. I need to try more combinations in my back yard and see what the best combination is for the least weight and space. Maybe the three clear trash bags will be adequate.

Ok I'll admit I've never used/tried a space blanket. A large yellow or orange gabage bag on the other hand I've used often. Great to signal in all seasons and can be useful for a variety of survival situations. Light, packs tiny, part of all my kits. But then again, so is the space blanket. I've just got to try one - one of these days...

Okay, for something a little more practical, try one of these:

http://www.land-shark.com/

http://www.adventuremedicalkits.com/products/KIT_e_ess_onebivvy.htm

http://www.rei.com/online/store/ProductD...t_cat=undefined

I believe these are superior for what we are looking for. They do take up quite a bit more space than the single sheet mylar bags or a large plastic garbage bag, but then again, they are much more sturdy and more suited to the intended purpose.

They are like the HD space blanket turned into a bag. Since both models are reinforced laminated bags, you should be able to use them quite a number of times if you are careful.

One time my brother and I made a nice fort in a perk hole out in the forest behind our house. We snatched a bunch of dad's visqueen and carefully spread it over the trench hole and sealed it off except for one end to climb into. Once we were both inside the hole we pinned the flap shut with a couple big sticks. All was well, for a little while, as we were out of the rain and reasonably comfortable. After a couple hours, it started getting a little tough to breath right, and we opened the end of the plastic and stuck our heads out and realized we weren't getting much O2 inside that plastic.

Be careful about snuggling down into a plastic bag and sealing it up nice and tight to get the heat up. It may turn into a body bag.