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# best down jacket for cold temps - Page 2

Quote:
Originally Posted by beyond

Tromano, all for simplified models, but not sure the conduction formula is relevant here. Isn't it primarily for calculating transfer of energy across solid, uniform non-living objects, like heating one side of a piece of aluminum and seeing what the other side's temp gets to? Living systems and their boundaries are all about convection, not conduction. Particles moving through fluids, whether air or water or something else. Think about how massive and dynamic the space is between skin and parka, then between inside and outside of parka, relative to the molecules that are carrying heat away from the body. Not a lot of direct conductance.

IMO, the convection diffusion formula is more what this needs: $\frac{\partial c}{\partial t} = \nabla \cdot (D \nabla c) - \nabla \cdot (\vec{v} c) + R$  As you know, that's stochastic differential calc if I dimly recall where my college math slewed to a halt. But it's used a lot in fields where heat transfer and convection are the issues. Here's an example from architecture: http://www.bse.polyu.edu.hk/researchCentre/Fire_Engineering/summary_of_output/journal/IJAS/V1/p.68-79.pdf, and here's an example from exercise physiology: http://ehakem.com/index.php/IJoT/article/viewFile/231/254

Bob, I suspect research groups at companies that make down/syn fills/vapor barriors routinely do computer models that use the above. I doubt that North Face et al. think about it when they actually make a parka. They just follow the simplified guidelines that filter down from the research groups. But this stuff is real; when I'm wearing a parka, its performance is all about convection, not conductance. That's probably the reason that loft doesn't fully explain why one parka feels different than another.

Convection means heat transported by flowing air. Your shell is wind proof, down jackets are wind proof. When skiing in an normal outfit with a shell over an insulation layer, not much air is flowing through your insulation. That means that convection is not an important heat transfer mechanism inside your insulation layer.

That leaves only conduction and radiation of heat. Heat transfer in an insulator (in heat or electricity),  is all about reducing conduction.

Quote:
Originally Posted by tromano

Convection means heat transported by flowing air. Your shell is wind proof, down jackets are wind proof. When skiing in an normal outfit with a shell over an insulation layer, not much air is flowing through your insulation. That means that convection is not an important heat transfer mechanism inside your insulation layer.

That leaves only conduction and radiation of heat. Heat transfer in an insulator (in heat or electricity),  is all about reducing conduction.

Could not disagree more. First, your conceptualization seems several orders of magnitude off. "Windproof" is a misnomer on a molecular level, because the issue is areas of more dense air molecules adjacent to areas of less. (That's wind, in fact.) Unless you're assuming thick vinyl plastic "parkas" that are literally impenetrable even to oxygen or nitrogen. Nylon allows plenty of molecules to move back and forth. Second, there is plenty of movement of air within the parka, molecules passing from one microscopic trapped air pocket to the next, from inner wall to outer wall. Abetted by your body movement while skiing. Water vapor works similarly. The rate of convection may be slower than that in an external system such as sweaty skin in open air, but it's still convection by any reasonable definition. I wonder if the problem is that the system we're talking about is not a homogenous solid.

I've already cited a couple of documents that show why convection is central to heat flow. One of them specifically addresses convection in insulation that's a whole lot denser than down. I know of no, zero, zilch, professional document that would back up your assertions. Show me, even though I'm not from Missouri.

Edited by beyond - 8/23/12 at 12:36pm
Quote:
Originally Posted by beyond

...I know of no, zero, zilch, professional document that would back up your assertions. Show me, even though I'm not from Missouri.

Wait a minute.  Aren't you still on the hook to prove that there is a significant (as opposed to theoretical) difference between (sticking with the OP) 550 fill power down and 850?  So...?

^^^^ Interesting that I'm on the hook for a conjecture (that it's loft, not fill power) that you initiated. OK, as opposed to those who type in stuff off the tops of their collective heads, here is some research, which you can read.

First, these are a good start: "Gao et al., Structures and Properties of the Goose Down as a Material for Thermal Insulation, 2007,Textile Research Journal, 77:617." and "Gao et al., Explanation of Fractal Configurations of Goose Down Composition, 2009, Textile Research Journal, 79: 1142." (The Chinese do a lot of work in this area since they supply most of the world's down.)

The two articles can be summarized as follows: Goose down has a fractal structure, right through scanning electron microscope levels of resolution, and that fractal structure (ratio of base to branch of 1.73) is in fact nearly the Golden Mean (1.66). This structure allows it to trap air, and compress or decompress, far more efficiently than structures such as wool, synthetics etc. And since it's a fractal, the greater the number of iterations, the more air molecules it can trap. It is this trapped air, which limits convection, that gives down its insulative qualities. The down fiber itself is not an important conductor. However, if down absorbs moisture, the fractal structure breaks down on a micro level, leading to loss of spaces in which to trap air molecules.

I think this takes care of both the convection question and the reasons behind the relevance of fill#. Higher fill not only is larger physically per individual down cluster, so less is required to fill the same volume, but it has more fractal complexity on the levels that matter to air.

Now as far as your question about "significant" differences, you're the only one who can decide what you mean by the term, and I'm confident you won't budge. But every single source on the web I looked at finds that fill # and loft are co-determinant of insulative quality. This from Wikipedia - which you couldn't have looked up because of your broken fingers  - is illustrative: "The higher the fill power the more insulating air pockets the down has and the better insulating ability. Fill power ranges from about 175 cm³/g (300 in³/oz) for feathers to around 900 cm³/g for the highest quality down. Higher fill powers are associated with a larger percentage of down clusters and a larger average down cluster size."

But in terms of actual tests, there apparently is one gold standard, the International Down and Feather Testing Laboratory. Here's the link: http://www.idfl.com/ You get to join, apparently there's a fee, without which you cannot read the specific tests that are cited all over the web by manufacturers and retail people.

Out...

This is the most boring argument I've ever seen on Epic (and that says a lot). Just get whatever down jacket fits your price/style and get on with your life

Quote:
Originally Posted by beyond

^^^^ Interesting that I'm on the hook for a conjecture (that it's loft, not fill power) that you initiated. OK, as opposed to those who type in stuff off the tops of their collective heads, here is some research, which you can read.

First, these are a good start: "Gao et al., Structures and Properties of the Goose Down as a Material for Thermal Insulation, 2007,Textile Research Journal, 77:617." and "Gao et al., Explanation of Fractal Configurations of Goose Down Composition, 2009, Textile Research Journal, 79: 1142." (The Chinese do a lot of work in this area since they supply most of the world's down.)

The two articles can be summarized as follows: Goose down has a fractal structure, right through scanning electron microscope levels of resolution, and that fractal structure (ratio of base to branch of 1.73) is in fact nearly the Golden Mean (1.66). This structure allows it to trap air, and compress or decompress, far more efficiently than structures such as wool, synthetics etc. And since it's a fractal, the greater the number of iterations, the more air molecules it can trap. It is this trapped air, which limits convection, that gives down its insulative qualities. The down fiber itself is not an important conductor. However, if down absorbs moisture, the fractal structure breaks down on a micro level, leading to loss of spaces in which to trap air molecules.

I think this takes care of both the convection question and the reasons behind the relevance of fill#. Higher fill not only is larger physically per individual down cluster, so less is required to fill the same volume, but it has more fractal complexity on the levels that matter to air.

Now as far as your question about "significant" differences, you're the only one who can decide what you mean by the term, and I'm confident you won't budge. But every single source on the web I looked at finds that fill # and loft are co-determinant of insulative quality. This from Wikipedia - which you couldn't have looked up because of your broken fingers   - is illustrative: "The higher the fill power the more insulating air pockets the down has and the better insulating ability. Fill power ranges from about 175 cm³/g (300 in³/oz) for feathers to around 900 cm³/g for the highest quality down. Higher fill powers are associated with a larger percentage of down clusters and a larger average down cluster size."

But in terms of actual tests, there apparently is one gold standard, the International Down and Feather Testing Laboratory. Here's the link: http://www.idfl.com/ You get to join, apparently there's a fee, without which you cannot read the specific tests that are cited all over the web by manufacturers and retail people.
Out...

Hey no need to get all huffy. I just thought it was kind of eye-ron-ick that when I asked for some proof of significant difference, you had nothin', but there you were asking someone else to back up their assertions. And look, here's an emoticon to help you keep a good humor about things:

Quote:
Originally Posted by JoeUT

This is the most boring argument I've ever seen on Epic (and that says a lot). Just get whatever down jacket fits your price/style and get on with your life

Well, clearly it's no match for back and forth bickering about the cause of fires, but it's all there was. Why, is it time for a helmet thread?
Quote:

Originally Posted by beyond

And since it's a fractal, the greater the number of iterations, the more air molecules it can trap. It is this trapped air, which limits convection, that gives down its insulative qualities. The down fiber itself is not an important conductor. However, if down absorbs moisture, the fractal structure breaks down on a micro level, leading to loss of spaces in which to trap air molecules.

I think this takes care of both the convection question and the reasons behind the relevance of fill#. Higher fill not only is larger physically per individual down cluster, so less is required to fill the same volume, but it has more fractal complexity on the levels that matter to air.

Yep. We are good.

Quote:
Originally Posted by Bob Lee
Well, clearly it's no match for back and forth bickering about the cause of fires, but it's all there was. Why, is it time for a helmet thread?

Looks like that one might be rearing its head again

A little early for a helmet thread, I'd say, but a wilderness user group debate seems like it'd be topical. I saw a thread over on MTBR about electric bikes and how they should be classified in terms of trail use. Had potential, but we'll need to throw in some anti-MTB hikers to give it legs in the more general environment here.

Quote:
Originally Posted by Bob Lee

I just thought it was kind of eye-ron-ick that when I asked for some proof of significant difference, you had nothin', but there you were asking someone else to back up their assertions. Yeah, most folks disagree about what proof is. To a physicist, it can be 100% math, to a psychologist it can be 100% self-assessment. Good thing Epic never descends to the schoolyard, "you started this, no you started this," level...

Why, is it time for a helmet thread? Absolutely. And if we have another crappy start to the season, I plan to start my own helmet thread by January, with detailed discussion of the molecular structure of EPS, mandatory exams every Friday.

Since 80% of heat loss occurs through the head (yes there is scientific proof, but it is top secret government stuff) I don't even know why anyone is talking about jackets

Down-filled liners for helmets is where it's at!

Awesome thread, I enjoyed that.  Epic Ski to never fails to deliver when I need my fix of pompous, over-analytical, over-complicated, self-amused and generally masturbatory responses to simple questions.

Regardless, here's a real-world comparo of 2 ultralight insulating jackets.  I own and wear both under a GoreTex hard shell unless there's no wind and no weather at all.  I'm in the layering school.  The combo of base layer + fleece + jacket + shell is good for pretty much any temp and any amount of wind (vary the weight of base layer and fleece). IMO neither jacket would be great for skiing without a shell - if you snag on a tree or take fall they're going to get shredded.  Anyway....

1.  Mtn Hardwear Compressor:  Primaloft.  Super light, very warm.  Great for sweat-producing activities - hiking, skinning, skiing.  Continues to function well when damp.  I sweat like a pig on the up, even if everything is completely unzipped, so I at times l get damp and this dictates clothing strategy.  With the Compressor it doesn't matter.

2.  Mtn Hardwear Ghost Whisperer:  850 fill down.  Super-mega-ultra light.  Astoundingly warm (though that's partly a perceived effect since it's virtually weightless).  Great for activities standing still - belaying, hanging out.  Maybe skiing too if you're the type that stops so much that you never really get warm.  When it gets damp it's done, game over.  It's so thin it doesn't take much moisture to kill it.  It's worth noting that the GW textile (and similar products from patagonia etc) has a moisture resistant coating to keep the down from wetting out.  The same coating also inhibits sweat dissipation and they can be clammy.  The point is, don't use these jackets for stuff that makes you sweat hard.

NB:  The performance of something like the Ghost Whisperer and similar jackets is NOTHING like heavier down puffies (Mtn Hardwear Absolute Zero parka).  They transmit moisture much better.

Hood or hat?  Personal preference, I prefer hat.  Both are proven technologies supported by over 10,000 years of development.

Now back to TGR for more concise and opinionated commentary on other topics............

Quote:
Originally Posted by kletter1mann

Awesome thread, I enjoyed that.  Epic Ski to never fails to deliver when I need my fix of pompous, over-analytical, over-complicated, self-amused and generally masturbatory responses to simple questions.

I personally own a FlyLow Iceman.  700 fill goose down, 2 layer, fully taped, 10/10K rating.  I live in CO and rock this coat at resorts when temperatures drop way below 0°.   Works great and I would recommend this coat for what you are looking for.   Prior to this I owned a Salomon Pocket Rocket down jacket which was insanely over kill.  Don't remember the specs.

Touring, slack-country, and mixed days that are cold I rock a FlyLow Higgins and either a Rab Micro Light or a FlyLow TC Vest.  If you are on a budget and can't afford a quiver of apparel this is the path I would recommend.  Solid bomb proof breathable shell with a couple of mid-layer options.

Most days I rock a hat versus a helmet.  Helmet is reserved for CB, A Basin, gnarly exposure, or when the traffic is high.  Basically I think ski helmets suck balls and are way over rated and If I am wearing one I get cold.  If you want a helmet that will actually provide a real world level of protection if the shit hits the fan you should buy a moto helmet.  Ski helmets suck at what they are suppose to do.  Marketing bullshit!

I make my apparel decisions based on feedback from people I trust and personal experience just like I do with skis.  Apparel marketing mumbo jumbo bullshit is pretty deep.

My 2¢'s.

Quote:
Originally Posted by PCLMS

If your not set on down jackets, synthetic is good too i find: the patagonia nano puff is good for just walking around. Arcteryx atom lt is good for when you are active.

I bought a Mammut Rime Pro jacket that uses synthetics instead of down.  It's pretty warm, and I live out here in the midwest.  used it for my ski trip last week, and it works great. Mammut also makes a non-"pro" version that is hoodless, if hoods are not your thing.

Bob Lee,

I don't have a scientific equation to help answer your question about whether a higher fill is actually warmer. But I can speak from experience.

I wrote a review a little while ago about the down that I use. If you look at the member review called KUIU Layering System. In a quick summary, I use the KUIU Super Down. It is 850 fill with real down feathers. Most down jackets with real down feathers are rendered useless if they get wet. The feathers in the Super Down have been treated with a DWR finish which makes them waterproof. The outside of the jacket also has a DWR finish. Therefore even if this down gets wet it will still retain heat. It is made in an athletic cut, it has both a hooded or zip t version. It is made with 2 way stretch material so the jacket can move and stretch with you. It is extremely light (hooded 10 oz, zip t 7 oz). It is also very breathable and moves moisture well. Another nice feature is that if you do get too hot, you can take it off and it folds into its own chest pocket. When completely compressed it is about 7 inches long, 4 inches wide, and 2 inches tall. It fits easily in my camelback that I bring with me on the slopes.

I know some of you are concerned about over heating with a 850 fill and skiing but for me the 850 fill has been perfect. If I am really getting after it, I do get warm, and when that happens I open up the pit zips on my outer layer, unzip my front zipper a little and I am fine. Then when I get to the bottom and have to wait in lift line / sit on lift I am always comfortable and never cold. On really cold days I also use the Super Down pants which are fantastic as well.

Before I had the Super Down, I had a North Face Landover down jacket. This jacket weighs in at 28 ounces which is 18 ounces heavier. It is 550 fill down so not as warm. Its appearance and feel are bigger and bulkier than the KUIU. But from testing in the field, KUIU has kept me warmer. It is also made with real goose down, but this goose down has not been DWR treated. The North Face down does have a powder skirt which I liked. The KUIU does not have a powder skirt, but it does have an elastic draw cord around the bottom that I synch up tight and it does the same job as a powder skirt. I have not had any problems in deep powder with snow coming up underneath.

As far as prices go:

North Face Landover costs:                      $249.99 KUIU Super Down Hooded Costs:$249.99

KUIU Super Down Zip T Costs:                 $199.99 KUIU Super Down Pant:$199.99

So in my opinion, you are getting a lot more bang for your buck from KUIU. When I tell my buddies about the gear they always ask why its so cheap, "if it's that cheap there must be something wrong with it!" The reason they can sell a more expensive product for a competitive price is because they only sell online at wholesale, which I learned from reading their blog. The blog is very detailed and gives you info on everything from why they select certain materials to how they run the business.

This is just my 2 cents. I prefer the 850 fill over the 550 fill I had before.

Quote:
Originally Posted by bomber5

Bob Lee,

I don't have a scientific equation to help answer your question about whether a higher fill is actually warmer. But I can speak from experience....

Since I have a lot of experience, that's where I quit reading.

fair enough, cheers bob

Quote:
Originally Posted by huhh

800+ fill down is WAY to hot to ski in.  The max a guy should need is 600.  You're skiing not standing around doing nothing, your body will produce heat.

I have an 800 fill down jacket (Marmot Quasar) over a thermal base layer, underneath a soft shell, and am only barely warm enough on 15 degree days.  I would be really cold if it were Rockies or Quebec arctic temps!   Some of us get really cold easily, and I am not burning many calories riding a lift.  Of course, for skinning, I would be plenty warm with that, probably too warm....

Quote:
Originally Posted by timo

I'm looking for warm down jacket for skiing in Breckenridge. Any recomendations?

Hi, Il keep it simple.

I shopped around for a warm ski jacket with the right features and down insulation and found the Outdoor Research Stormbound jacket. I have used it quite a bit and its my go to ski jacket when skiing in temps of 15F and below. I have used it in temps of -5F~0F with great results with just a baselayer and light fleece under. As it gets warmer the pit zips help a lot in controlling the temperature.

I think there are a few other similar options out there from other manufacturers.

Most down jackets are NOT made for skiing and do not have a durable enough outer fabric so they can rip after a fall or two.

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