how breathable a wind shell is

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    nian zhang
    BPL Member


    Hi Richard,

    It's interesting to know the Squamish has similar breathability as a normal shirt. Does it mean they have similar wind resistence? If it's the case, does it mean I can just use base layers to achieve the same effect? E.g. begin with a T shirt, if windy put on a long sleeve shirt. Can you test the CFM of a two bases combo like this? I am asking because I also always bring two base (T + long sleeve).


    Richard Nisley
    BPL Member


    Locale: San Francisco Bay Area


    I am confused by the technical terms you mountain climbers use to describe air permeability. How does "quite breathable" compare to "windproof",” “wind-resistant,” and “breathable”? (smile)… just kidding.

    Richard Nisley
    BPL Member


    Locale: San Francisco Bay Area


    I most recently answered your question on combining air permeability layers here:

    The Squamish I tested would have similar wind resistance (aka air permeability) to the main nylon fabric used in either summer shirt I mentioned. The summer shirts have an open mesh panel on the sides to achieve more air permeability and the Squamish has a deep center zip.

    Brendan Swihart
    BPL Member


    Locale: Fruita CO

    Thanks for all the info, Richard; it's appreciated.

    I'm curious if there are different types of CFM measurements…in the post you just linked (from 09) you list the Houdini as 5 CFM compared to the 40+ in this thread (including model yrs 08 and 09). Are those different types of measurements?

    Roman Vazhnov
    BPL Member


    Locale: Russia

    Richard, yes i understand that the same model may have different fabrics from year to year, even fabrics with the same name can have different characteristics within the family. I wanted to say (+1 to Brendan) – may be there are different methodics? Because this numbers (around 100 for windshirt) are rather great. People used Squamish for winter backcountry travel and so on, and reviews said that air permeability was on pair with similar windshirts.

    For example this are the numbers from your post in 2009:
    "Polartec Windbloc 0 CFM… PU layer
    Gore Windstopper <2 CFM Porous Teflon membrane without the Gore PU layer
    eVENT <2 CFM Porous Teflon Membrane (hard shell product for ref only)
    Driclime windshirt 3 – 5 CFM
    Patagonia Houdini windshirt 5 CFM
    Polartec Powershield 8 – 16 CFM Perforated Membrane
    Polartec Windpro 60 CFM
    200 wt Fleece 200 CFM"

    Which numbers are correct? Maybe the numbers from the table above are from manufacturers, not from independent test?

    Another assumption – was it (Squamish) new? Maybe PU coating inside was worn out?

    Richard Nisley
    BPL Member


    Locale: San Francisco Bay Area


    There is only one standard for air permeability. In contrast, there are a large number of different MVTR breathability standards. When comparing windshirt fabrics to eVent fabrics only air permeability is relevant.

    In '09 I didn't own an air permeability tester. I purchased it in 2011 and tested the Houdinis from prior as well as subsequent years. In that old post I used the Patagonia Houdini air permeability specification that was in a Patagonia Power Point presentation that Mark Verber posted. Hopefully Mark can tell us the year of origin for that presentation.

    Richard Nisley
    BPL Member


    Locale: San Francisco Bay Area


    I 2009 I didn't own my own air permeability testing equipment and had to rely on vendor specs. In early 2011 I purchased an air permeability tester and since then I have used the old "trust but verify" approach to vendor's air permeability ratings (smile).

    Roman Vazhnov
    BPL Member


    Locale: Russia

    Thank you, Richard. Can you consider the opportunity to post the table with cfm for all garments you have tested?

    James holden
    BPL Member


    well richard …

    if im soaking in sweat more than a balding middle age man in a vegas porn convention … it aint breathable ;)

    absolute "windproofness" isnt usually an issue as youre putting on a belay jacket when not moving anyways … and you may also have a light synth puffy when moving over technical terrain

    Eric Blumensaadt
    BPL Member


    Locale: Mojave Desert

    I'm not balding and I'm well past "middle age" but I DO live in 'Vegas. You mean they have porn conventions in 'Vegas? Geeze, now THAT would make me sweat so maybe I shouldn't wear my windshirt when I go.

    "Seriousnessly", when hiking in mountains I always wear a long sleeved poly or nylon shirt for UV protection. That shirt is the only one I carry other than two poly T-shirts. Thus no DEDICATED windshirt. Of the four shirts I have the "511" brand nylon shirt is the most windproof and the polyester REI Sahara the least. The altitude and season dictate which one I take.

    But still they provide enough protection that I can wear a medium weight (200 wt.) polyester fleece vest beneath them on cool, windy days and be just fine. Their vented backs are covered by my pack. Around camp the eVent parka goes on.

    Mark Verber
    BPL Member


    Locale: San Francisco Bay Area

    > that old post I used the Patagonia Houdini air permeability specification that was in a
    > Patagonia Power Point presentation that Mark Verber posted

    it was 2005. The Patagonia windshirt back then was called the dragonfly. My memory is that the first generation houdini which came out in 200? used the same fabric but a slightly different cut / zipper configuration.


    Peter Fokkinga


    Locale: the Netherlands


    Do you intend to test the new autumn 2012 version of the Houdini (1.2-oz 10-denier fabric) as well?

    I fear its "blocks more wind than the previous version" feature, in combination with the slimmer fit, could mean it is actually a step back from the previous version :(

    Richard Nisley
    BPL Member


    Locale: San Francisco Bay Area


    I will test a Autumn 2012 when I get access to one. I don't have a scheduled date.

    Michael Cheifetz
    BPL Member


    Locale: Israel

    So I wrote pertex directly and Montane as well and received the below answers (that I am not sure about…)
    Thanks for contacting Pertex®
    Air permeability of Pertex® Microlight is less than 3cfm.

    The figures we have from Pertex for Microlight are 1.0cc max (JIS L 1096/ ASTM D737).

    anyone can figure this out? how does it sit within the scale @nisley measured the Houdini??

    there is also this post by @nisley

    Quoting 15.59 for the same pertex

    Richard Nisley
    BPL Member


    Locale: San Francisco Bay Area


    The ASTM D737 standard on page 3 says, "11.1 Air Permeability, Individual Specimens—Calculate the air permeability of individual specimens using values read directly from the test instrument in SI units as cm3/s/cm2 and in inch-pound units as ft3/min/ft2, rounded to three significant digits.”

    Pertex’s response of <3 CFM is the air permeability reading using the ASTM D737 imperial representation and the Montane’s response of 1.0cc max is the equivalent ASTM D737 scientific representation which is 1.97 CFM; they are effectively equivalent values.

    15.59 CFM is what I measured for the Microlight fabric used in the Montane Lite-Speed version that Ryan Jordan, Roman Dial, etc. selected for use in the 2006 Artic 1000 trip. The hang tag on the fabric I tested said, “Pertex Microlight E.B.P. Fabric for Body”.

    Also in 2006 Pertex sold the company to Japan based Misui. At the time of the sale there were at least 9 Quantum variants and 5 Microlight variants with different weights and air permeability ratings for each one. The Quantum variations offered a smaller air permeability range than the Microlight variations. Your 2012 Pertex Microlight product specification is different than the 2006 variant that I tested.

    The ASTM D737 standard tests I conducted, for multiple years of Houdinis, use the same CFM test value representation as Montane and Pertex.

    O S


    Locale: SF Bay - East Bay

    Just found out the new Houdinis (as of mid 2012) aren't siliconized, they are treated with a DWR. (probably still done in the Epic process, i.e. woven from preg'd yarn)
    Might look the same under microscope, but it's not silicone.
    It does contain some flourocarbons, so I opted to avoid it.

    Simas Peciura


    How did you find that out?

    Rob P
    BPL Member


    Don't laugh….I have 2 of these!

    I keep the blue one for the most part in my golf bag, folded into its chest pocket. It is a "stretchy" material. I also have a blaze orange one I like to wear for fall hiking (keeps me visible in case hunters are around)…It is clearly a different material…less stretchy and more like a traditional "windbreaker".

    Richard, If you have any interest in testing these different materials, let me know.

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