Registered: 02/07/07
Posts: 3917
Loc: Ozark Mountains in SW Missouri
I would try using 3M glue to laminate a SOL blanket to a fleece blanket and use that as an under quilt. The reflective surface should be on the bottom, facing the hammock. I would cut slits (or slots) in the reflective surface if moisture build-up was a problem.
Or, I would try a piece of the breathable reflective material I linked to in a previous post all by itself.
Just got back from an overnighter - temps got down into the 20-25 degree range. I used the 66" NeoAir All Season (third night of use) and stayed plenty warm - essentially the same results as the two previous nights.
Registered: 07/11/10
Posts: 597
Loc: Fairbanks, AK
Actually, I have been thinking about it. I have the time, I'm just in the middle of a very bad case of winter hibernation. Though so far I have two backpacking trips planned - one in March in Cali (3 nights) and one in early May nearby (another try at Chena Dome.)
So I'll attempt to start this project (I have parts for a camping stove, a wrap-around insulated skirt... well you get the idea.)
Registered: 11/24/11
Posts: 6
Loc: kent island, md
I used the regular neoair (L) with the 1/8" thinlight underneath in temps down to 17 degrees last year in PA. the ground was very cold, been low temps for weeks. I use the thinlight as a sit pad and to protect my neo air. I can say that when kneeling on the neo air, I could definately feel the cold, very cold, when on parts not over top the thinlight pad. I stayed warm all night using this combo and WM badger, just longjohns.
This year I've been in temps down to 11 degrees with the Xlite and 1/8" thinlight-same sleep system, and stayed very warm and comfortable. Though whatever tactile material is on the bottom of the Xlite grabbed and shredded my thinlight as I tossed in my sleep.
Bill I like that idea or I may bond sol to synthetic insulation like phat talked about. I havent had time to get to wallyworld yet. The slits to ley moisture out is a very good idea. I may face insulation with sol on one side and ripstop on the other?
Bill I like that idea or I may bond sol to synthetic insulation like phat talked about. I havent had time to get to wallyworld yet. The slits to ley moisture out is a very good idea. I may face insulation with sol on one side and ripstop on the other?
Speaking from experience, the "reflective factor" is hugely overrated compared to the chill you'll get from the fact that underneath you won't breathe. I'd try it without the reflective blanket.
You could add a full length 1/2" generic blue closed cell foam pad to your regular NeoAir. I've done this down to 20 degrees. Below 20 degrees, I would go with a 3/4" closed cell foam like the thicker Ridgerest. These add-on pads are also useful for sitting on in camp around a fire or whatever without worrying about damage to your expensive NeoAir.
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Registered: 02/07/07
Posts: 3917
Loc: Ozark Mountains in SW Missouri
Originally Posted By phat
Speaking from experience, the "reflective factor" is hugely overrated compared to the chill you'll get from the fact that underneath you won't breathe. I'd try it without the reflective blanket.
My experience has confirmed none of that, no "chill" no "condensation", no "moisture" issues at all, and as I've pointed out several times, there is a breathable reflective material available one might try if those are a problem for you.
I suspect there's only a limited amount of IR radiation to "capture" and that moar reflective layers aren't additive, like R-values. If someone, for example, is already using a reflective NeoAir (not the Trekker) adding still more reflective layers isn't likely to do much.
Registered: 02/07/07
Posts: 3917
Loc: Ozark Mountains in SW Missouri
I'm sure you're right about adding more reflective layers, but I'm pretty sure that not all reflective layers are equally efficient. The one on a NeoAir is probably not near as efficient as those on emergency blankets, so an emergency blanket under a NeoAir may help keep you a bit warmer, but I'd suspect it wouldn't be much.
It also makes a difference on how close the reflective surface is to your body, so one placed on top of your NeoAir may also help keep you warmer. Since the NeoAir material does not breath, I see little downside in trying it on top of one if you're cold.
When reflective layers touch they become effectively worthless. A reflective layer is usually thin and metallic. That means they have high conductivity and very little heat capacity. They will quickly equilibriate with what ever they are touching. If you lay a Neoair on a reflective layer, the two will quickly become the same temperature. It won't matter what the reflective property of the layer it is sitting is since the radiation exchange is occurring inside the mat, thus only the reflective properties of the mat matter. Because of conduction the space blanket's radiative properties are moot. Now you proposed, a bubble mat with a reflective layer. The bubbles are designed to reduce conduction between the top and bottom. However you do indeed get a diminishing return on each additional thermal layer. I suspect Neo Air's already use multiple radiation layers inside the pad(at least the new ones), so you probably won't get much additional benefit regardless.
I can go into the equations if you are interested.
Registered: 02/07/07
Posts: 3917
Loc: Ozark Mountains in SW Missouri
Quote:
If you lay a Neoair on a reflective layer, the two will quickly become the same temperature. It won't matter what the reflective property of the layer it is sitting is since the radiation exchange is occurring inside the mat, thus only the reflective properties of the mat matter.
I think you're wrong about that.
What is relevant is how much radiant heat is passing through the neoair layer and if any of it can be reflected back inside the NeoAir by the bubblefoil layer.
The bubble foil reflects about 96% of radiant heat. I've looked at the reflective material on a NeoAir and I doubt it achieves that efficiency. It just not near as reflective. That's what I based my assumption on when I said placing bubble foil under a NeoAir might add a bit of warmth.
I think I also said it works better if you lay it on top of your pad.
Quote:
I suspect Neo Air's already use multiple radiation layers inside the pad(at least the new ones)
Since mine is not a new model, that would seem to confirm my observations. The trick for them is getting the reflective layer about 1/8" under the top of the mattress with airspace in between, like bubble foil does. No easy trick, they can't trap the air, the pad won't pack down small if you do that.
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It seems clear to me that how well these non-breathable reflective materials work is a very personal thing, might be somewhat regional and weather conditions based too.
Phat apparently gives off more moisture than I do, and because of that a SOL type layer does not work for him. There's nothing strange about that, we're all a bit different. But because they don't work for him is no reason I should not use them if they work for me.
As I've said, I think the material can be improved, or at least improvised better, for our needs. I even found and linked to a lightweight breathable reflective material that I think should be tested to see if it solves the kinds of problems Phat and others have experienced. I looks to me like it very well could, but I can't test it, I have not been able to duplicate those problems.
If that stuff works, just like it is, not yet optimized for our use, it could potentially lower your bags comfort rating by 10º, weigh less than 650 fill power down to do it, and cost less than $10.
Just because WM hasn't figured out how to incorporate it into their bags yet doesn't mean it can't or shouldn't be used. One reason they probably can't put a reflective layer inside a sleeping bag yet is because it loses its efficiency too fast, the shine wears off of it. But don't think they (and others) aren't still working on it. Whoever figures out how to use it first will have the lightest bags on the market.
I am not, but perhaps we are talking about two different things. My first comments were in regards to just a reflective layer.... like a space blanket. Your bubble layer will prevent conduction between the reflective layers. Your bubble layer could be quite effective with a lower R-value neo air, however putting a space blanket under it won't help much. You are in essence making it closer to how the newer higher R-value neo-air's (I suspect) are designed.
I agree adding a light breathable reflective shell material to a sleeping bag could greatly improve efficiency. Problems could involve having a loud crunchy sleeping bag with an uncomfortable fabric, but it would be interesting to see how it turns out. It sounds like you should get into the sleeping bag business.
There were a few such options back in the '70s and '80s. The only one I had first-hand experience with was from Early Winters--considered an ultralight model back in the day. Did the reflective layer make a difference? Heck if I know (since you couldn't, uh, rip it out to test). It wasn't a luxurious bag, but back then 800+ci down and advanced synthetics didn't really exist, either.
Cascade Designs considers their pads to be part of their sleeping systems, so if they feel it's warranted they might market a quilt or overbag with an IR layer.
Cheers,
Originally Posted By BZH
Originally Posted By billstephenson
...
I think you're wrong about that.
I am not, but perhaps we are talking about two different things. My first comments were in regards to just a reflective layer.... like a space blanket. Your bubble layer will prevent conduction between the reflective layers. Your bubble layer could be quite effective with a lower R-value neo air, however putting a space blanket under it won't help much. You are in essence making it closer to how the newer higher R-value neo-air's (I suspect) are designed.
I agree adding a light breathable reflective shell material to a sleeping bag could greatly improve efficiency. Problems could involve having a loud crunchy sleeping bag with an uncomfortable fabric, but it would be interesting to see how it turns out. It sounds like you should get into the sleeping bag business.
Registered: 02/07/07
Posts: 3917
Loc: Ozark Mountains in SW Missouri
Quote:
No need to wait, you can have a bag with reflective layer today. (Scroll down to "radiant.") It'll cost ya.
Their you go.
The only thing is, he says they put the reflective layer on top of the down. I believe that the reflective layer would work better if it were placed 1/8"-1/4" above the inner layer (closer to your body), and with the down on top of the reflective layer to add R value.
The best solution might be to add a very thin inflatable layer made with a reflective surface inside the top layer of the bag. A NeoAir that's 1/8' thick if you will. That obviously has the "spring a leak" draw back, but it might work incredibly good too and it would inflate with just a puff of air.
Originally Posted By BZH
It sounds like you should get into the sleeping bag business.
I'm just a futzer at heart. The design, testing, and manufacturing processes interest me, but the business side doesn't a bit.
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