Quilt thoughts / questions

Posted by: PaHiker

Quilt thoughts / questions - 10/27/17 02:36 PM

Have a quilt that sufficed for warm 3-season usage, but when moving into the colder times it's not a consideration. Thought I would give a try at a cold 3-season quilt. Had a wacky idea pop into my head (happens all the time) so I thought I would pass it by here for reasons why I am on / off base.

What would be the problem with using a reflective foil inside the quilt, in place of the usual down / therma-whatever. I've used these in SAR to get a person warmed up until help arises. I have one that has seen better days for SAR, but might have a use as a quilt liner.

Posted by: OregonMouse

Re: Quilt thoughts / questions - 10/27/17 05:15 PM

Believe it or not, one of the most important features of the standard sleeping bag/quilt is that it's permeable. This is important, because your body gives off quite a bit of moisture (the technical name is "insensible perspiration") during the night. If either the outer or inner shell of the bag/quilt is waterproof, the bag will trap moisture inside.

Of course a number of us use a vapor barrier inside the sleeping bag in really cold weather, which adds to the warmth. However, you don't want anything inside that vapor barrier except a suoer-moisture-conducting base layer. Any insulation you may want to add on an extremely cold night needs to be outside that vapor barrier, or it will be soggy (and not very insulating) by morning.

I strongly recommend, from long experience, that whatever vapor barrier you use (and that foil layer you're contemplating is a vapor barrier) be separate from the sleeping bag. On warmer nights, you won't need it, and it will feel like a Turkish bath inside. The borderline here is different for different folks--for me it's about 30* while for others it's more like 20* or 15*. On extra cold nights, when your quilt/bag is marginal, you'll need to be able to add insulating clothing over the top of your vapor barrier, not something you can do if the barrier is part of the sleeping bag shell.
Posted by: PaHiker

Re: Quilt thoughts / questions - 10/27/17 05:24 PM

Thanks, do understand that. The foil we use does have holes to allow vapor to escape.
Posted by: BZH

Re: Quilt thoughts / questions - 10/31/17 10:50 AM

so... radiative shields (reflective foil) are not designed to be conductively insulating. What that means s they only work if they have some space between them and any object around them. They don't work very well sandwiched between objects like you are proposing.
Posted by: PaHiker

Re: Quilt thoughts / questions - 10/31/17 11:01 AM

Okay, thanks. Somehow I figured life wouldn’t be that easy.