Continuing a discussion on Steven Evans Cuben/down quilt thread, Hunter and I have simultaneosly been thinking about a SUL quilt idea.

I've been to the shops and bought a painters poly dust sheet. Man these things are thin, a ragged toenail would go straight through. So I went in my gardening shed and pulled out some polthene sheet which is about six times thicker. I'll be playing with it when I get back from the Lake district on sunday.

Steven asked about air valves. Since these quilts won't be blown up hard, low tech will do for now. Fold and tape.

I'm planning on a 6 layer job using row cover (horticultural fleece) at 20g/m2 and the light dust sheet plastic sandwiched inside the heavier gauge plastic, making 3 air pocket layers and a trapped fleece layer. To avoid getting damp, there will be sealed holes through the plastic layers covered by two outer layers of fleece, which will also trap air between the 'mounds' of air filled plastic.

Target weight is 9oz, but that might rise to 11oz with a heat sheet cover with perforations in. More soon.

Edited by tallbloke on 05/29/2009 09:29:59 MDT.

I would have thought reflective mylar film might have fitted in well into this idea! From radiant heat saving too

Roger, what are you trying to accomplish? I seriously doubt that it will be anywhere close to warmth/weight ratio of cuben/down quilt.

Have you seen these?

Blizzard Pack

I've slept in one of the bags - wasn't bad. They also do blankets.

**Wear earplugs**

Edited by andydolman on 05/29/2009 10:35:19 MDT.

Huzefa,
Tim said buying one of his cuben/down bags would cost $450, this project would be very cheap in comparison. I think cheap MYOG projects are praiseworthy (although the more expensive ones like the cuben/down bag are great too!).

You could MYOG the cuben down quilt for around $200. $450 is if i make it for you.

-Tim

I've been using expanded polythene sheet for years (NOT polystyrene), as a sit mat, groundsheet protector, etc.

It seems to be a remarkably good insulator, because of all the sealed pockets of air. When we last had a winter with any decent snow (20-odd years ago...), I was travelling to work by train. I kept a bit in my bag to either sit or stand on, waiting on cold station platforms. The snow underneath never melted, and that was with 3mm thick sheet.

I once played with the idea of making emergency bivy bags out of the stuff, and I always carry a torso-shaped piece when I'm walking, for use as a sit mat for stops, and potentially an insulating casualty mat in the event of an energency.

It's light and cheap, and comes in many thicknesses. I recently salvaged loads when the place I work bought lots of big plasma screens; it's often used as protective packaging.

The downside is that it's quite bulky. But I reckon a few sheets of the thinner stuff could make quite a good insulating quilt.

I thought of this as I was wondering whether you could somehow texture, ripple or waffle the argifleece you're using, so that it can trap pockets of air better.

A Cuben shell would protect the really feeble decorator's sheet.

It's all getting a bit complicated...

Hi Derek,
an order of magnitude (at least) more body heat is lost by conduction and convection than by radiation, and a mylar film would add a couple more ounces, so I'll make the prototype without, and then try putting a reflective film over to see how much difference it makes compared to an extra layer of light air filled poly. An important part of the aim is to make this as condensation free as possible. Also, as Andrew points out, mylar film is noisy, though the silvered heat sheets made by adventure medical aren't. I just got a new one of those through the post and I may sacrifice it to the experiment. Putting the film in the middle of the quilt with a layer of row cover will help damp noise.

Huzefa, we don't know until we try, and it won't cost much to find out. I can't afford a cuben/down quilt. And I like the idea of a quilt which would roll up and fit in my pocket. :o)

If it works well, I'll consider spending some money on some cuben to shell it with. I anticipate that putting some effort into shaping will be important, as will the size, number and placement of vent holes.

Kevin, are you talking about bubble wrap, or something else? Expanded polythene sounds interesting, but being able to expel the air and wrap this small is part of the aim.

Work begins tomorrow.

Edited by tallbloke on 05/31/2009 15:13:54 MDT.

We all know that air-beds offer virtually no insulation. Why would a quilt be any different?
Unless you had thousands of little air pockets, each with their own valve, to stop the air movement?

Hi Mike. I think there are several factors which have got air a bad rep as an insulator. Air beds are under a high pressure, with channels which allow drafts underneath. They don't breathe so the sleepers back get clammy, and then cold.

I think that with a bit of care and thought, an air quilt will be light, warm and very packable. I will be covering it with horticultural fleece, which will trap air between the 'bubbles' of the inflated quilt, and insulate the air in the inflated quilt so that the convection currents will not be as strong due to a lower temperature differential between sleeper and top surface. I will also be putting a layer of the fleece between the inflated layers. Condensation will be minimised by heat sealing the plastic layers together with a hot metal tube every 5" or so. The inner circles can then be cut out to make breathing holes which will be insulated by the breathable fleece top and bottom.

I'll know much more by tomorrow morning.

Edited by tallbloke on 06/01/2009 03:01:20 MDT.

Roger, take a look at this thread from back in 2006, about the now long defunct Pneugear Cocoon 4. Scroll down a little to where the ideas start. Perhaps this might help give you some ideas?

Thanks Miguel, interesting read. I'm not trying to compete with the temp rating of the Pneugear, just make something warm enough for summer nights, and maybe as a booster for a down quilt in winter. But then, it'll weigh closer to 8oz than 8lb !

I'm struggling a bit with heat sealing very thin polythene. I may have to wait a couple of days for some double sided tape to show up. Failing that, the prototype gets the silicone gun. :o)

Edited by tallbloke on 06/01/2009 08:11:37 MDT.

I was just about to finally make a posting (I have been swamped lately) when I noticed roger went ahead and did it himself(less work for me). Im glad to hear that many people like the idea and have had it before thus making it more likely it will be completed. I have been pondering some ideas lately and will soon be posting them. I really like the idea of using reflective Mylar film and foil tape for construction. I feel that there will be a lot of condensation problems so I have been thinking that a ventilation strip with fill like on the cuben/down quilt. I know the reflective Mylar film will easily get holes but it will work for now.
Im excited to see other prototypes; I will make mine and post it soon.
Keep the posts coming guys!
Hunter Nelson

Ok so I went insane not building this thing and doing other work so I dropped every thing else and built a prototype. Its not pretty its not any thing I will bring backpacking soon but it works and is a excellent start. I had this super strong orange bag that was bought for me as a survival tool. I taped off the open end and filled it with air( I was lazy so I used the air compressor) then I made a foot box by folding in the corners like the ray way quilt. I also added loops( 3 on each side ) and ran thread through them to pull the quilt down over the edges pulled tight.
The quilt is really warm, I got in it and in no time I had a pounding head from overheating and I bet if I had some less air I wouldn’t get as hot( plus its hot out today). The quilt is rather small but it is a prototype also I would like to say that it has 3-4 in loft and is not near fully filled. As expected the material sucks to feel on your skin, I like the idea of using silk inside or another material. Dose any one know of any materials that would feel better and hold in air?
I plan to sleep in the quilt tonight and I will make a posting tomorrow about my feeling on it, im having trouble getting pictures up they should be up by tomorrow.
Also I think a good way it fill it in the field is using the air bag system used on pack rafts.
Hunter Nelson

Roger,

Expanded polythene is a kind of bubble wrap, but it's not made using a regular array of bubbles formed by welding of two layers of polythene; it's a sheet formed from a random matrix of aerated polythene.

Have a look at:

Jiffy Foam

Once you know what you're looking for, you'll find it in all sorts of electrical packing. A more fragile version is used as laminate floor underlay.

I got sidetracked in my earlier post, The reason I was reminded of Jiffy Foam is that a ribbed variant is available; this might usefully trap additional air between the layers.

Ah, thanks again Kevin. It would be interesting to find out the weight of that stuff. The row cover is a non-woven polyethylene 'felt' which is around 20g/m2.

My kitlist notes say a 185x52cm piece of the 3mm thick sheet weighs 150g. I'm not sure whether this is measured or estimated... the round number makes me suspect it's estimated.

I'll try to remember to dig out some of the plasma screen covers and measure it.

The stuff you're using is 'gardening fleece', by the sounds of it. Is that right?

Yes, horticultural fleece, row cover - same stuff. Comes in various weights but I have some of the uberlight 20g/m2 stuff. About 7.5 times lighter than your jiffy foam.

I measured the stuff last night.

The 3mm thick sheet (that I use as a sit/casualty mat) weighs 73gsm (vs 156gsm I suggested yesterday; as I suspected, that must have been a guess). The plasma screen wrapper, which is a laminate of thin poly sheet and thin expanded polythene sheet is 25gsm.

I'd suspect that the 3mm sheet will provide significantly more insulation than the fleece.

I gave a short test of the plasma screen wrapper as quilting; it's a wide, one-end-open bag, so I got in it, and folded the wide part over me to give three layers on top, and one underneath. I seemed fairly warm, but then it was a warm night, and a short test...

The plasma screen wrapper sounds very interesting at 25gsm. Where can I get some in the UK I wonder. Got any trade name for it I can search for?