"Good people do not need laws to tell them to act responsibly, while bad people will find a way around the laws." -Plato
The reflective qualities of space blankets only work at very close distances. Other than that, you get wind and moisture blocking in a compact, light, cheap little package. Any inner layers of space blanket in a sandwich are blocking air movement, but not doing much if anything in the way of heat reflection. Just the top layer closest to your body is doing any real reflection. If you use polyester batting in a space blanket envelope, the bottom surface is blocking movement and moisture and just completing the package for a dead air space.
This stuff is okay for temps above freezing to get a quick and dirty insulation package. For colder temps, nothing will beat a good thick layer of insulation. It's all about cost, compressibility and weight for the protection provided.
So then by this, instead of building my sandwich of (from bottom to top) cheap nylon/SB/Polyfill/super cheap breathable fabric. I should flip the SB and the Polyfill? Does that sound about right?
Un-covered batting will leak heat. The slightest breeze or air current will reduce the heat carrying capacity. Then you think, well, put the batting on the inside of the quilt, against the hammock, and then SB on the outside...
That will work too, but the SB will trap moisture. With it sandwiched, the batting will retain less moisture, but if you're sweating, you'll wake with a wet backside...
As-it, it's an expedient, cheap UQ.
If I were to make one like this, I'd get some cheap, light fabric and forget the SB. If you want it really warm, fleece the inside layer. of course, that means weight...
See now, that's super interesting. The camp blanket thing I'm using now is just a nylon shell with a fleece lining. Works great down to at least 50. It's what actually made me think about adding a SB. So maybe it would be better, your saying is basically I'm better off with what I have? At least until I start to do them cold weather hangs.
A space blanket will act as a vapor barrier, keeping your perspiration from migrating into your insulation, but vapor barriers are most effective in sub zero weather, where perspiration will actually freeze in your insulation and stay there. In those conditions moisture can continue to accumulate, adding weight and killing the loft and insulating properties.
Last edited by DaleW; 09-17-2011 at 10:03.
Ahhh, I got it. That actually puts this whole thing to rest for me then. Thanks for the clarification. I'm actually in better shape than I thought. Or rather my sleep system is.
DaleW, any update on in-the-field testing?