Climashield vs. Polarguard

From a legal stand-point, I can assure you that even if the military funded the development of a material, there is no possible way for them to take part of the revenues from sales of a civilian product.

Regarding your suspicsions about clo test validity: I remember seeing some info on whiteblaze.net and here on BPL about CLO values that explained how some fibers allow heat transmission better than others. The same rationale seems to work when comparing different types of building insulation at Home Depot (ie: Fiberglass vs Cellulose, etc). The clo rationale convinced me, but I know that many people still believe in using loft for synthetics rather than clo.

For laboratory tests, I'd use the new European tests that use controlled humidity and a brass dummy as the most authoritative.

A huge factor with the Pac Outdoors pad is that it uses Aerogel, which is a space age foam that basicly allows you to stand in dry ice with just a Toasty Feet insole (with Aerogel) as the barrier.

Interesting topic- you seem to be in a perfect position to test your distrust of published clo values, and of the underlying premise that loft is not always the best determinant of warmth.
If you have two quilts of the same specs, differing only in their insulation, can you find a somewhat objective way to test how well they retain heat? I remember reading about some homebrew test where a heating pad was heated to a known heat, placed under a sleeping bag and the pad was measured periodically to see how much heat was reatined over time…
I am sure a good test will be trickier than I propose, but people on this forum are bright, they can come up with something.

Thomas, I'm not an expert by any means, nor have I done any MYOG projects involving these two insulators, nor have I even seen or felt any Climashield in person. Take what I say with a grain of salt.

Insulation is not all about trapping dead air. Ultimately, it's about stopping the progress of heat transfer via radiation, conduction, or convection. Trapping dead air is a decent way to do this, for sure, but it's not necessary. Aerogel, for instance, doesn't trap any dead air, as far as I know. It's a solid (the world's lightest, actually). Aerogel's wonder is that if you have a sheet of the stuff and you apply heat to one side, it takes an awfully long time for that heat to transfer through to the other side. This is of course what allows the famous pics of Aerogel plates with a blowtorch hitting it on one side, and a box of matches or a human hand on the other side. No air is trapped here, it's just that heat isn't getting through the material.

Ok you probably knew all of that, but think about Climashield. If it's better than Delta at stopping heat transfer (due to, I dunno, the particular kind of material that it is?) there's no reason why it would need the same amount of loft. I'm sure you know that a similar warmth could be provided by our benchmark Aerogel in a much, much thinner, less lofty thickness, right?

That's my $.02

If I may add a bit to the discussion. When you build a house you have to consider how the materials that you use will affect the insulating abilities of the house. If you build two walls of the same thickness, one made of stone, one of wood, the one of wood will make the house feel warmer. This is because of the convective value (R value) of the materials. That's why when you stand, with the ambient air temperature the same in both rooms, in your bare feet in a room with a stone floor and one with a wooden floor you will feel warmer in the room with the wooden floor.

The same must surely go for fabrics. One of the interesting things about wearing the Mont Bell Thermawrap jacket from 2005, with its thicker outer nylon shell and the Thermawrap jacket from 2006 with its thinner nylon shell is that the 2006 jacket feels colder not so much because of the thinner shell (the insulation is the same in both cases), but because the thinner shell, when you place your hand on it while walking in the cold outside, actually acts as a heat sink, feeling much colder to the touch than the 2005 nylon shell.

Certainly my Pertex Microlight shell feels much warmer than the MontBell Airlight shell when I touch it outside in the cold.

Climashield must somehow work on this principle, the material of the fibers itself drawing less heat than that of Polarguard. And I think that when making insulated gear with a shell and insulation fill it is probably important to think of the heat sink value of both the insulation and the outer shell.

Here is a great article linked on the Mammut site about sleeping bags and temperature ratings. Includes info on history, tests, and suggested clo to temp comparisons. The most informative part for me was on the testing using copper and brass dummies and thermal imaging. Basically, CLO is a pretty decent objective way to compare insulating capabilities.

Article URL: http://www.mammut.ch/mammut/uploadedFiles/Sleep%20Well_Pt1_E.pdf

Edited because I forgot to paste the URL.

My guess as far as reviews about the Aerogel sleeping pads not seeming warmer than thermarests is that both have fairly high R values. In most cases a Thermarest is more than sufficient. In those conditions the Aerogel pad would not be of any benefit, a la no noticed difference. Just a possibility. In addition Aerogel is a solid, but from what I can gather, Ian, it is trapping air… micro pockets of it that used to be occupied by the liquid that made it a gel.

Thomas, you mention that higher fill powers of down provide more warmth for the same loft. From what I understand about down, this is not quite right. 800 fill power means that one ounce of that grade of down will fill 800 cubic inches I believe, whereas one ounce of 600 fill power will fill only 600 cubic inches. However, if you take the two and make a 2" loft sleeping bag the result will be that the 600 fill power bag will be warmer and heavier but the 800 fill power bag will be cooler and lighter. The actual comparison is between weight and loft, not warmth for loft.

The thing is, down is very compressible, so volume changes easily, thereby altering density. Density of down is much more of a factor of how the bag is manufactured, how much down is stuffed into the given space of the baffle tube. Higher fill powers allow for less dense and lighter bags I believe because the down feathers themselves are less dense.

This is at least how I understand down insulation to work based on the info I've read.

As far as how well this translates into synthetics? From personal experience, equal thicknesses (lofts) of Primaloft are much warmer than equal thicknesses of other synthetic insulations I've used. This goes right along with your ideas of less dense = more loft… I just wonder, as you do if loft is all there is to insulating value. Primaloft is more dense I guess, but still more efficient based on warmth/weight according to the CLO tests. This is most noticable with Primaloft One which is the synthetic with the highest CLO/oz value of .84 but is way way thinner at all of its weights than comperable insulations. This is only my own subjective findings though.

As far as your thoughts about breathability.. that is an intersting point. I would be very interested in getting some info on how breathability affects insulating ability.

I am also curious about the sudden disappearance of Polarguard, so if you find any more info on that, or do find that it is warmer, please do post your findings!

I have long taken issue with the "loft=warmth" line that so many people tout.

If that were true, the warmest sleeping pad would be a 6" air mattress. This is hardly the case.

There are lots of articles on here measuring a product's loft, or its' ability to regain loft. I believe that there was one comparing down and synthetic vests where they actually use "loft" and "warmth" interchangeably.

I think that then relationship between loft and warmth is more variable than that, and has a lot to do with the insulator. I think that some insulators need more "loft" to produce an equal amount of insulation, and that some insulators are not 50% less insulating when they've collapsed by 50%.

I'd love to see BPL test that with a copper dummy, actually.

Hey good point, I remember the article you're talking about, where they soaked some down and synthetic jackets or something to that effect. That article did definitely equate insulating power to loft, as I recall. Or if it didn't equate them explicitly . . . it gave my un-expert mind that distinct impression.

Hm, this could be kind of important.

Thomas & Ben,
There seems to be some confusion about down fill ratings vs warmth…

Warmth for a down bag boils down to warmth per inch of loft only because the feathers used in all down bags are "pretty close" to the "same" material – from a heat-transfer and air-trapping insulation perspective. (Actually, the Clo value of 800 fill weight down should be SLIGHTLY better (and therefore warmer) per inch of loft than 600 weight down since 800 weight down has less thick feather "branches" between the "down duff" than 600 weight down.)

A down bag with 2" of loft using 600 weight down will have the same temperature rating as a down bag with 2" of loft using 800 weight down – the bag using 800 weight down will just be lighter and more compressible. The extra compressibility of 800 weight down would theoretically make the BOTTOM of the bag very slightly cooler AT THE CONTACT POINTS (such as hips and shoulders). However, in practice, 600 weight down compresses so much it's also almost fully compressed (ie: non-insulating) where your body's contact points press unto the sleeping pad hard. (Both weights also seem to fill in the hollows between contact points just fine). So the real practical difference between down bags is still just that the 800 fill bag weights less (usually about 1/2 – 2/3 of a pound in a 20 degree bag).

Hopes this helps.

Thanks for the info on down insulation John! So basically with down, unlike with synthetics, the material is essentially the same, therefore loft is what determines warmth?

Hi Ben,
For practical purposes, Yes – with Down: Loft equals warmth. 600 versus 800 weight down only effects the weight of the bag if the two bags have equal lofts in inches.

(For "theoretical" purposes: 800 fill "should" be a tiny bit warmer than 600 weight down per inch of loft due to less stiff feather "branches" holding up the down "duff" in 800 weight down).