Idea for a UL sleep pad.

[1forcamping]

For a while now I've had the idea of using radiant reflective barrier insulation (aluminized polyester, space blankets, etc) in camping gear. My big idea was to use it in a sleeping pad, but I recently discovered that it's already been done (Thermarest Neoair). By now, I've gotten used to having ideas only to find that Someone else had them first, but what shocked me is how much the pad costs.

Out of curiosity, I started looking up "space blanket material" on the internet, and found that "radiant reflective barrier insulation" can be bought in bulk for use in insulating buildings for a fairly low cost.

Why not mate this stuff between two thin layers of closed cell foam so theres no heat conduction, and make what's basically a 2oz heavier version of a Z-lite pad, with R values of something like 7.5-15?

It sounds like it should work, but I'm half skeptical that it would, just because of how simple it is.

If anyone has a way to construct and test this inexpensively, or has any helpful input as to whether or not this would actually work, please feel free to comment

Thanks for your time.

[jesse]

Space blankets are not very durable.

[1forcamping]

There are more durable versions of the material available. The military used similar material in "casualty blankets" which were basically tarp-like in strengh and weight.
Other good examples are the Adventure Medical Kits thermal bivies.

http://www.adventuremedicalkits.com/...r&prodname=SOL

Although the stronger versions are heavier, I'm wondering if having the lighter material surrounded in closed cell foam would provide enough protection for practical camp use without having the weight penalty.

If not, the more durable options still don't weigh that much.

[leaftye]

It's not the regular Neoair (R-value 2.5) that has that radiant barrier, but the new currently unnamed all-season Neoair (R-value 4.9).

I doubt your idea would be nearly as warm as you think. Since you assume your idea would only be about 2 ounces heavier, the thickness of you pad must be about the same as the Z-lite. R values basically add together, so the warmth of the foam components will be the same as the Z-lite, while the radiant barrier may add another ~2.5 if it's the same as the new Neoair. That leaves you with an R-value around or slightly under 5.

You can do this yourself inexpensively. Give it a shot. It'd be easy.

If you really want an R-value over 7.5, and especially 15, you need an inflatable pad. That means switching to open cell foam, using heat sealing fabric, figuring out how to bond to the aluminized surface well enough that the aluminum doesn't delaminate. This would probably also be much bigger and heavier...my wild guess is 5 pounds.

[1forcamping]

You can do this yourself inexpensively. Give it a shot. It'd be easy.

If you really want an R-value over 7.5, and especially 15, you need an inflatable pad. That means switching to open cell foam, using heat sealing fabric, figuring out how to bond to the aluminized surface well enough that the aluminum doesn't delaminate. This would probably also be much bigger and heavier...my wild guess is 5 pounds.

Possibly. I know the reflective barrier has R values up to 15, but it depends on the application. That's where I was hoping the closed foam would help. It seems like the main weekness of the insulation is conduction. I figure the foam should protect from that pretty well, but I also don't know how well it will work with the foam.

The neoair mattress does use the reflective barrier, but because it's only separrated from the ground by thin vynyl, which I think would make it more susceptible to conduction.

As for trying this out cheaply, what would be a good, inexpensive way of sandwiching the barrier insulation between the foam layers, and holding it all together, while maintaning flexibility?

You mentioned heat sealing fabrics. Is that something I could pick up at a hardware store? Is there any special equipment needed?

[leaftye]

Possibly. I know the reflective barrier has R values up to 15, but it depends on the application.

Please show me an application like this?

As for trying this out cheaply, what would be a good, inexpensive way of sandwiching the barrier insulation between the foam layers, and holding it all together, while maintaning flexibility?

Rolling up this concoction would stretch out the mylar, possibly causing it to fail. Using some sort of horizontal strips might work, or quilting.

You mentioned heat sealing fabrics. Is that something I could pick up at a hardware store? Is there any special equipment needed?

Maybe if you have a particularly awesome hardware store, but I doubt it. For foam, thefoamfactory.com. For heat sealing fabric, seattlefabrics.com. I don't know what you'd use to bond the foam to the fabric or for the valve. For the valve, use a Thermarest repair valve. You can do the bonding with an iron or modified soldering iron.

Personally, if I were trying to build an R15 pad, here's how I'd do it with a radiant barrier. 30D heat sealing fabric, thermarest valve, 24" wide, fully baffled, 3.5" inner baffles, 4.5" outer baffles, 900fp down, vertical baffles for simplicity. The radiant barrier would not be structurally tied in, which means there would have to be multiple vertical strips that are glued in away from the baffle bonds. This also means that there would be an upper and lower baffle, which also makes the pad warmer like the Neoair. So making wild guesses....lots of down might get you up to R9, double layering adds R1.5, radiant barrier adds R2.4 for a total of R12.9. The radiant barrier might be applied to the upper and lower side of the barriers, creating three baffle layers, but I don't believe that would as additive, but might get you up to R15. I might actually replace the lower radiant barrier with Insultex. My wild guessing would place this pad around 3 pounds, with much of the added weight due to the extra width and layers of fabric.

[WI shepherd]

Tek Foil is one manufacturer of radiant reflective barriers/insulation. Their website has information on various designs of this stuff.

http://www.teksupply.com/farm/suppli...nsulation.html

If you are experimenting, why not just get a roll of foil insulation, cut to size, and sandwich your pad between the foil insulation by taping the edges of the foil together, then test. I question if reflective foil insulation can handle a lot of wear and tear, but using even a sheet of it under a pad for a few cold weeks may help.

[Rocketman]

The aluminized mylar reflects infrared radiation (IR). In the air, between a warm body and a cold body there is a fair amount of radiation.

Sadly, there is little radiation transport in a closed cell foam. The foam absorbs the infrared wavelengths and doesn't transmit them. So, there is no IR to reflect, and the space blanket sandwiched between two closed cell foam layers has nothing to do.

This is likely to be the reason that such an obvious device is not on the market.

A long time ago, the idea of a foam sleeping bag was tried, and retried...... and nothing survived the test of time.

Edison is said to have tried a thousand ideas for a lamp filament before he met success.

[WI shepherd]

I misunderstood the OP with sandwiching mylar between closed cell pads, not around them, sorry. I did go out to a shed, cut a 6' long, 24" wide piece of Reflectix double-sided, bubble insulation, found it weighed 10.8 oz and would roll up into a 16" diameter log (roughly the same size as my closed-cell pad.)

http://www.reflectixinc.com/basepage...&pageIndex=622

[Awol1970]

Personally, if I were trying to build an R15 pad, here's how I'd do it with a radiant barrier. 30D heat sealing fabric, thermarest valve, 24" wide, fully baffled, 3.5" inner baffles, 4.5" outer baffles, 900fp down, vertical baffles for simplicity. The radiant barrier would not be structurally tied in, which means there would have to be multiple vertical strips that are glued in away from the baffle bonds. This also means that there would be an upper and lower baffle, which also makes the pad warmer like the Neoair. So making wild guesses....lots of down might get you up to R9, double layering adds R1.5, radiant barrier adds R2.4 for a total of R12.9. The radiant barrier might be applied to the upper and lower side of the barriers, creating three baffle layers, but I don't believe that would as additive, but might get you up to R15. I might actually replace the lower radiant barrier with Insultex. My wild guessing would place this pad around 3 pounds, with much of the added weight due to the extra width and layers of fabric.

PM me when your done and tell me how much you are selling them for. It sounds like you probably know what you are talking about.

[NCarolinaHiker]

Is the new Neo Air not called the Trekker? Seems a lot of unknown info out there for a product being sold at many retailers currently. Questions on R value, cost, and weight included.

[leaftye]

Is the new Neo Air not called the Trekker? Seems a lot of unknown info out there for a product being sold at many retailers currently. Questions on R value, cost, and weight included.

No. The Trekker is on the MSR website with a R2.5 rating.

[NCarolinaHiker]

Eugene, is that not the pad you referred to above? The original NeoAir is supposed to be R2.5, and the Trekker I've seen at R2.0 and R2.5.

Is another highed R value Neo headed our way or am I confusing myself?

[leaftye]

Oops, I hope I didn't add confusion. The Trekker is R2 on the MSR site, not R2.5 as I incorrectly stated.


Here's the new unnamed warmer R4.9 Neoair.
http://www.trailspace.com/blog/2011/...n-neo-air.html

Here is the radiant barrier.


The rating seems optimistic...an additional R2.9?? I believe thermo neutral is R6 and radiant heat accounts for only 10% of heat transmission losses with the rest being conduction and convection.

[NCarolinaHiker]

Actually you cleared it up, I've seen references to the new, warmer Neo Air and incorrectly thought it was the Trekker model - I haven't seen or heard of the Neo you linked to.

Thanks for that.

[1forcamping]

Sadly, there is little radiation transport in a closed cell foam. The foam absorbs the infrared wavelengths and doesn't transmit them. So, there is no IR to reflect, and the space blanket sandwiched between two closed cell foam layers has nothing to do.

I'm not entirely sure. I know IR tends to pass through most synthetic materials.

I happen to have an IR pass filter for my camera in the mail though, so it won't take much for me to see if I'm wrong.

I could also try to make the top layer of foam thin enough to allow IR reflection from the foil, while thick enough to protect the foil from abrasion. The point being that the foil will reflect IR instead of absorb it, while the foam prevents conduction of heat from the foil to the air or ground.

I know there is probably a good reason no one has done this, but I figure I might well work with the idea, and see what I can get it to do.

[1forcamping]

Here's the new unnamed warmer R4.9 Neoair.
http://www.trailspace.com/blog/2011/...n-neo-air.html

Here is the radiant barrier.

This looks awsome.

[Rusticus]

ive used a car windsheild reflector, not much padding but it will keep you warm and only weighs about 3 oz

[Don H]

ive used a car windsheild reflector, not much padding but it will keep you warm and only weighs about 3 oz

Did you do this on top of a pad? If so what type of pad and at what temps were you still comfortable at? Right now I'm using a 1/4" thick foam pad from Gossamer Gear over a Neo. Seems to work but I'm always open to new ideas.

[Rusticus]

i used it on its own, mostly in a hammock but it worked in the shelter too its at least as insulating as a ccf pad, and almost as comfortable, they make them in different thickness, i used the thinnest one, i think it was around 2 dollars at walmart, so pick one up and try in out, i thought it worked great for being almost full legth and only 3 or 4 ounces