Hi all,

I saw so many people here praising their wind shells. Just wondering how breathable they are compared to latest hard shell like Gore active shell, event or dry Q. Like 10%, 20%, 50%? I am thinking if wind shells only offer a little bit (around 10%) of more breathability then I probably will not get one.

In fact I already got a Montane pertex wind shell. I used it several times but it seems there was not too much difference with my event shell. I meant when I work hard I sweat anyway. Or when it's not that windy or even sunny I probably will just hike in my base layer. And in winter or cold days I have no problem wearing my event shell all day with only my base layer or a synthetic jacket/vest (I have both). And since my synthetic jacket is wind proof, I sometimes just wear it without a shell. Moreover a hardshell provides much more breathability when the underarm zip is open. So I ended up using the wind shell only for cycling in cold days because it's guaranteed to have lots of wind chill and it's more slim than my event shell. At this point I'd ask is wind shell really necessary when you have to bring a hard shell anyway because I will bring a hard shell anyway since I am the type of always preparing for the worst. And my hard shell is sub 300 g (westcomb specter lt), it's really not a huge difference in terms of weight with most wind shells.


But I saw so many people praising their wind shells about breathability etc, I began to wonder are their wind shells much more breathable then my Montane pertex? If yes, does it mean it's at the cost of windproofness? If there is a windshell providing 'significant' breathability then my event shell and still is wind proof or very much wind resistent then please enlighten me.

NZ

Nian,

A hard shell made with a porous membrane, such as eVent, provides “worst case rain protection” in combination with air permeability as high as .53 CFM. This is what I measured on the Integral Designs Thru Hiker. I measured the air permeability of the Rab Boreas windshirt, which Dave C. gave the highest rating in his recent SOTM report; at 68.69 CFM but with no external moisture protection. THE DIFFERENCE is 68.69 / .53 = 1,296%.

To put the windshirt air permeability spectrum in perspective, the most breathable windshirt I have measured is the Acteryx Squamish at 100.59 CFM. The windshirt that will achieve the optimal balance point, for most people while UL backpacking, is the Houdini.

I measured the older Pertex Classic fabric and it was 3 CFM. Assuming this is the Pertex fabric used in your windshirt, it is a very poor choice for use while UL backpacking. I also measured the North Face Verto windshirt using the newest Pertex GL fabric and it was even worse at .53 CFM, the same as the Thru Hiker eVent. I then had a forum member, who purchases a lot of Pertex fabric, contact his rep. The rep's spec for the fabric was less than 1.97 CFM.

At a 7 MET exertion level (UL backpacking average), in average summer mountain temperatures and wind conditions, most people find the Houdini air permeability the optimal windshirt available. I measured the spring 2012 version of this windshirt at 35.8 CFM. The reason its air permeability is optimal is that this is the level of air permeability that will JUST PASS the AVERAGE EVAPORATED SWEAT moisture while UL backpacking. More air permeability than provided by the Houdini is not a wise choice for most people.

As air permeability goes up, wind resistance and external moisture protection goes down. More air permeability than is required to pass through your sweat is not a benefit. The key to selecting optimal windshirt air permeability is matching the air permeability that will just pass your average evaporated sweat level without venting. Venting can then be used for augmentation.

A windshirt that would never limit your maximum possible work potential requires ~400 CFM air permeability and would be worthless for protecting you from any wind or moisture. It is a balancing act.

Edited by richard295 on 05/28/2013 11:03:22 MDT.

@richard
by any chance did you ever measure the Montane Fetaherlight? is there a post here with more data RE other designs apart from the Houdini and Boreas?

10x
Mike

Mike,

I didn't measure the Montane Featherlight air permeability. Any article and most forum posts I have seen on BPL has provided only subjective windshirt air permeability ratings. Unfortunately, most manufacturers also do not provide air permeability test data.

You can roughly ball park a relative position estimate by comparing the windshirt you are interested in to one of the three low, medium, and high references, that I provided, using a “air suck test”.

Edited by richard295 on 11/26/2012 14:05:24 MST.

@richard - unfortunately no real access to that type of gear here in israel :(

RE pertex - Montane uses "pertex microlight" - is that the classic?

RE Houdini - i assume that is the older model...i gather the new one is less permeable
Is the driclime similarly specd?

M

Richard,

Very interesting figures, you are a scientist :)

My pertex shell is Montane feather light smock. If it's only 3 CFM then may be it's not enough for me. Saw that Houdini a lot, maybe will get one. Do you by any chance test other material like Marmot driclime?

Thanks for those figures, very informative.

Nian

It should be breathable. I wear my sierra designs kenosha wind shirt while sleeping and I never wake up with damp clothes. I can't say that about sleeping with a rain jacket on.

I am going to pass on creating forum posts dealing with the testing of the less mainstream windshirts that were released in various years.

I tested the Houdini versions for these years:

2008 Houdini = 47.01
2009 Houdini = 43.85
2010 Houdini = 38.12
2011 Houdini (Military Special Edition) = 35.42
2012 Houdini (Spring Version) = 35.80

I tested the Marmot DriClime for only one model year:

2010 DriClime = 24.25

Both of these windshirt brands are near the sweet spot of air permeability required for UL backpacking but, the fixed thermal insulation layer of the DriClime limits its versatility.

One thing clear to me is the term "windshirt" is very nebulous without knowing the model / year / and its respective air permeability.

Edited by richard295 on 11/26/2012 16:54:30 MST.

I thought that Dave did a good job on his two windshirt SOTM articles but, based on the published Boreas material specification; it was too porous, too heavy, and too prone to snagging to garner an "A" rating, for most people, in the spectrum of UL windshirts. I acquired one and lab tested it to see if how it compared to my preconceived notions.

Its air permeability tested about half way between the Houdini and Squamish. At that air permeability rating, its equivalent breathability competitors were the myriad Polartec Wind Pro jackets. Since those jackets weigh at least 2x more, I was forced to acknowledge that it could conceivably be considered UL relative to them with comparable weather resistance.

There is no magic windshirt; as air permeability goes up, external wind and water resistance goes down. Whichever windshirt just barely achieves the necessary moisture transport for your average MET (7 for backpacking) is the optimal solution.

For my personal backpacking use, a layered Houdini (with Velcro added to fix the big wrist problem) gets my A rating. The material used is an EPIC process which keeps the DWR active for the life of the garment. At 7 MET (backpacking average) it needs to transport ~8,000 – 10,000 g/m2/24 h which it does. In contrast, an eVent jacket can only transport about 5,000 g/m2/24. If you are a jock like Dave C. your average MET would be higher and hence the attractiveness of a garment like the Boreas.

For highly aerobic activities such as jogging, a layered Squamish would get my A rating. This option passes transports more body moisture and has better external wetness protection. The material is a weave in contrast to a knit like the Boreas; as a result it is much less prone to snagging during bush walks.

Thanks for the fantastic post, Richard.

Yet another example of "there is no single best ______ for ______".

Far too few product evaluations acknowledge the variability between individuals and also variability between different conditions. This one goes out of it's way to hilite those differences.

edit: "shoot first, aim later ... kinda;-)" after posting I took the time to peruse the entire thread and ... Richard has more than one post here that rates my appreciation.

Edited by jcolten on 11/26/2012 18:07:55 MST.

"For my personal backpacking use, a layered Houdini (with Velcro added to fix the big wrist problem) gets my A rating. The material used is an EPIC process which keeps the DWR active for the life of the garment."

What do you mean by a "layered" Houdini? It is a term am unfamiliar with. Also, is the Houdini made with an EPIC style encapsulated thread?

Many thanks for your input.

Tom

In comparison to Richard's testing, after trying both the Houdini and Boreas, I found that I consistently overheated in the Houdini in moderately cool and windy temps. On the other hand, I have found the Boreas to be a perfect top for wearing by itself or layering while climbing, hiking, or running. Like Richard mentions, I think this is where personal preference, body chemistry, and climate come into play, as I run a little hot and don't choose a windshirt for its DWR.

Edited by aaronufl on 11/26/2012 18:34:11 MST.

Thanks Richard, I'm not a numbers guy (obviously), so your thoughts are highly valuable.

I did give the Houdini an A-, which I'd change to an A if the stock shell fit like my modified one. Having both is a nice quiver. The Houdini gets used a lot this time of year. A wool t-shirt, Cap 4 hoody, and Houdini is great for steady work in mixed weather (e.g. snowbiking and XC skiing during an intermittent snowstorm this weekend).

Pertex Classic (aka Pertex 5 or 6) is a lot heavier, and I assume less breathable, than either Microlight or Quantum. Good to do your research here.

Edited by DaveC on 11/26/2012 18:46:45 MST.

Tom,

I used the term layered to differentiate the Houdini use from the DriClime in my prior post. I meant that I layered a different base layer under it based on the expected conditions versus always using a moderately thick layer under it like is built into the DriClime.

See http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=6696&skip_to_post=47736

Back in 2007 I first pointed out that my micrograph indicated that the threads were encapsulated as they are in the EPIC process.

I can post again - cool.

Personally, I find Gore-Tex to be one of the biggest scams around. It's breathable compared to a cheap PU coated raincoat, but it's not very breathable compared to a soft-shell. I've never been impressed by W/B fabrics since their inception in the late 1980s. My W/B jacket/pants stays in my pack and is only used when/if the weather turns foul.

I bought a Patagonia Houdini wind shirt in 2010 and it's probably the most versatile piece I own. It's DWR finish is excellent - will handle mist, very light rain, and snow. It's extremely breathable so you don't get hot and clammy like you do while wearing a W/B shell. For me, it excels when I'm doing things like climbing up a mountain on skis, where I need to break the bitter wind, but Gore-Tex will just roast me. It's the perfect garment. On a day where I'm doing a lot of up-hill climbing on skis or mountaineering, I'll wear Patagonia Guide Pants, syn underwear, syn base layer top, and the Patagonia Houdini jacket. When I stop, I'll toss on a parka.

In the summertime, if the weather window is looking decent, the houdini is all I'll carry for wind.

Edited by redpoint on 11/26/2012 19:31:37 MST.

"I meant that I layered a different base layer under it based on the expected conditions versus always using a moderately thick layer under it like is built into the DriClime."

This and the link make things perfectly clear. As always.

Thanks again, Richard.

Thanks for the post Richard! I find myself needing to replace my Houdini. I was thinking about getting the Squamish from a feature perspective, now that I see the higher CFM, I am sure the Squamish will be my next windshirt given past experience comparing your and my comfort set point.

I don't suppose you have the CFM for Equilibrium used in the Rab Alpine Jacket Pullover?

--Mark

Mark,

Pertex specs that fabric at 10 CFM. The other Pertex fabrics I have tested were close to their specs.

Knowing how little insulation you require compared to me makes me think you would be happy with the Squamish.

> Pertex specs that fabric at 10 CFM.

Hmm... what confuses me is that my memory is that the Equilibrium in the Rab Alpine was more air permeable than my Houdini. Alas, I can't verify my memory because I sold my Rab Alpine and haven't yet purchased the smaller size yet.

--Mark

Richard,
Is that CFM for the current Squamish? Looks like there's a couple different names from different years of the fabric used (gossamera, luminera) and I'm wondering if it's still that breathable...