A Visual Paradigm for Windshirts – Multiple Axis of Understanding.-Rev 0

[Nick Gatel]

How important are ALL four components?

We can't have everything at the same time — or you can't have your cake and eat it too :)

For me (1)breathability and then(2)durable are most desirable.

(3) Next comes weight.

(4) Water resistance is last, because it will suffer if my first two items are of most importance.

I like the latest axis chart, which shows the older Houdini meets my important criteria, which I can anecdotally confirm.

[Richard Nisley]

Jeff correctly pointed out that the Rev. 2 chart could be interpreted that an item has more water resistance as it gets lighter.

This was a limited data set artifact. The simplest clarification was to add the Wild Things WT 1.0 EPIC fabric windshirt.

[David Chenault]

Thanks Richard, keep up the good work.

I do wish Wild Things would put a more refined hood on the tactical windshirt.

[Richard Nisley]

David,

Thanks for the positive feedback.

For bushwhacking in perpetually damp conditions, I have found the WT 1.0 fabric without equal. If a fabric doesn't test well for my intended purpose, I just get rid of the garment. If I keep it, then I inevitably find a few tailoring issues to moan and groan about. After that, I make the DIY tailoring changes to optimize the garment for my needs.

Tailoring Issue 1: Like you, I found the hood lacking. It’s only cut for "under helmet" applications and there are no options to adjust its volume or head position. To correct this, I always wear a wide brim hat with it; the hat has an internal adjustable head band size. It allows me to customize the WT 1.0 hood volume and position the way I want it and keep it in place under the hat.

Tailoring Issue 2: I want to close the wrist aperture when heat needs to be retained and loosen it up, along with the neck zip, to facilitate chimney effect cooling when needed. I rarely take off my pack to make clothing adjustments. I added Velcro wrist closures.

[Paul Hatfield]

Graph of Air Permeability (CFM) x Hydrostatic Head (mm H2O) for the garments that Richard tested.

This is my take on interpreting the data.

[Ken Larson]

This data might interest some:

The Alpine Start is at 40 CFM

FROM:
Brad Curkendall
Black Diamond Equipment

[Richard Nisley]

Ken,

Thank you for the information!

Needless to say but, the CFM spec is near optimal for aerobic activities; what is the companion HH spec?

Also please inquire if both of these specs are based on Black Diamond's tests or Scholler's tests?

[Ken Larson]

Richard …..I did not inquire, an over sight!

[Paul Hatfield]

I received this response from Black Diamond:

---

Thanks for getting in touch with us. The jacket is 40 CFM (cubic feet per minute) which is technically 40 CFM/M2 (cubic feet per minute per meter squared) but the industry simply refers to this as CFM. This is testing done by Schoeller and tested by BD. It is a stretch fabric and should increase the CFM slightly when stretched.

The hydrostatic head is approx 500 mm. It is treated with Nanosphere but does not have any coating that is generally required to get higher hydrostatic performance.

Kim Hall | Black Diamond Equipment

[Richard Nisley]

It is false that, “40 CFM (cubic feet per minute) is technically 40 CFM/M2 (cubic feet per minute per meter squared)”

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."

Kim may have the English representations and the SI representations mixed up. If so, a 40 SI value equals a 78.74 CFM value. As a general rule, EU companies (Schoeller is Swiss) spec their values in SI format.

[Wim Depondt]

I owned a Black Diamond Alpine Start Hoody but returned it. Black Diamond needs to work on its fit: the diameter of the neck area was so small that, during a hike, the jacket slowly but certain became uncomfortable to wear when fully zipped up (read: the zipper constantly pressing against my Adam’s apple). I normally wear a size medium but this problem also occurred wearing a size large.
I found the RAB Boreas and RAB Alpine significantly more comfortable to wear: the Boreas has more stretch and the Alpine is less athletic (which I find a plus).

FWIW:
– The ‘suck test' revealed the wind shirt to be in between the RAB Boreas and the RAB Alpine (RE breathability) But it is a close call – lab tests will certainly be more conclusive.
– The DWR finish is superb – the best I have personally ever seen. Most probably as a result of the Nanosphere finish. Superior to both the Boreas – which by default doesn’t have any DWR – and the RAB Alpine. I am very curious how durable this DWR would be as a result of both frequent washing and abrasion. At first sight, it seems Nanosphere is just a coating ( a special coating though as both fluorocarbons and nanoparticles are used to enhance repellency). Quid ‘Nanospere coating’ = as durable as ‘Nextec EPIC encapsulation’? I personally have to little knowledge to answer this question.
Patent information on the Nanosphere coating can be found here:

https://www.google.com/patents/US20080214075?dq=patent:20080214075&hl=en&sa=X&ei=m9QRU_i9M5KM7AaCr4GIBQ&ved=0CDUQ6AEwAA

– The RAB Alpine and – certainly – the Boreas start leaking faster than the BD Alpine Start under modest rain. But I would be surprised if HH would be around 500mm (as apparently claimed by a BD rep). I would rather settle for double or triple the HH of the RAB Alpine (anecdotal & arbitrary assessment). My cheap nylon Decathlon wind shirt certainly has a higher HH than the BD Alpine (but crap DWR).
– The BD Alpine Start has a 2-way stretch fabric and is – as is the Boreas – clearly less fragile then the RAB Alpine (the RAB Alpine is certainly not designed for lengthy sections of bushwacking).. The RAB Alpine has virtually no stretch.

Interesting to note: while the BD website state the fabric is 93% nylon and 7% elastane, the tags of the jacket tell otherwise: 93% polyester and 7% elastane. It was difficult to assess which statement is correct.

I will continue to use my RAB Alpine wind shirt. It remains a notch more breathable and is significantly more comfortable than the BD Alpine Sport. Compared to the Boreas, the RAB Alpine withstands drizzle and short rain showers but is still breathable enough to quickly ‘belay’ my rain jacket over it when it starts wetting through (which I find a very big plus in miserable weather).

edit: typo

[Eric Blumensaadt]

I have never used a "wind shirt" and never intend to. The extra weight is not worth it for something so specialized.

Instead my eVent parks is my wind shirt if my long sleeved poly or nylon hiking shirt can't protect em enough. It's about "dual purpose" gear to lighten the load.

[Richard Nisley]

Wim,

Thanks again for a very comprehensive and interesting review!

You have really piqued my investigative interest.

[Bill Segraves]

I'm late to this party, so please feel free to redirect me if this has been covered fully elsewhere, but what is the relationship between the wind resistance and water vapor diffusion rate? Does CFM tell us everything we need to know until we get down to windproof, or might there plausibly be differences in water vapor diffusion among fabrics with similar wind resistance? Within some relevant range?

Thanks much!

Best,

Bill S.

[Richard Nisley]

Bill,

Rain-proof shells have a requirement for a minimum hydrostatic head of 1,500 mm H2O; they are not required to move aerobic level moisture levels to the outside. To achieve this, the most common alternative is to use a nonporous lamination or coating. They utilize the polymer's molecular movement (micro Brownian movement) to efficiently absorb perspiration vapor and disperse it throughout the fabric but, have an air permeability of 0 CFM. The more expensive and efficient alternatives utilize micro-porous coatings or membranes but they are limited in air permeability to a maximum of about .5 CFM in order to fulfill the HH requirement. Moisture vapor transmission tests are the only way these two broad classes of technologies can be compared. There are many different tests used and results from different tests are not comparable.

In contrast, non-rain-proof shells (windshirts/soft shells/etc.) have the primary goals of moving internal aerobic level moisture levels to the outside, adding warmth, and protecting users from the wind as their primary goals; they are not rain-proof. There is a general but, not universal, inverse linear correlation, between CFM and HH. They are primarily compared using their CFM and HH values. There is only one universal test to determine each value and so they can be accurately compared.

[Bill Segraves]

Thanks for your reply, Richard. I think I must not have phrased my question right, or I'm missing something. I'm not wondering so much about the relationship between HH/rainproofness and CFM (though it's important, of course), but about how directly CFM tells us how well sweat will get out (the water vapor transfer rate). Will a 15 CFM garment dissipate 5 times as much sweat and insensible water loss as a 3 CFM garment? Will that 3 CFM garment dissipate 9 times as much as a 0.33 CFM propore garment? Will all 3 CFM or 15 CFM garments, for instance, be about the same? (If I understand correctly, *not* all garments of 0.33 CFM would be expected to be the same.)

Best,

Bill S.

[Richard Nisley]

William,

The answers to all of your above questions is "Yes" up to approximately 400 CFM. Furthermore, the porosity (CFM) and the associated convective permeability are more predictive of the capacity of an ensemble to support evaporative cooling than diffusive permeability (MVTR).

[Bill Segraves]

Thanks, Richard. That's helpful. It seems pretty clear why that would be the case wrt the maximum water vapor transfer rate that can be sustained without getting any significant condensation. But when I'm not venting adequately, I almost always first start to build up condensation on the inside face of my garments. Once that happens, the other properties of the fabric might make a *lot* of difference, right? Potentially the difference between whether I can stay just a little bit damp (MVTR approx equal to perspiration and insensible water loss rate) or instead get drenched?

My questions are partly just out of interest and trying to understand whether there's potentially another relevant dimension for your model, but also motivated by trying to understand why some low porosity garments actually seem to perform decently wrt water vapor transfer.

Cheers,

Bill S.

[Roman Vazhnov]

"The ‘suck test' revealed the wind shirt to be in between the RAB Boreas and the RAB Alpine (RE breathability)".
Wim, can you please clarify the ordering: Boreas < Alpine Start < Alpine ?

[Wim Depondt]

Yes, but I have to admit I now have second guesses and I can’t redo my ‘suck test’ anymore as I have returned the BD Alpine Start.

I can recall with much certainty that the RAB Alpine is more air permeable than the Alpine Start. But I now started doubting whether the Alpine Start is more breathable than the Boreas or vice versa. Maybe BPL member and staff David Chenault might be able to confirm/correct the order of breathability (I think he still owns the Boreas and has recently purchased the BD Alpine Start).

Wim

[Serge Giachetti]

I breath tested the alpin start vs. Rab alpine & found the alpine start to be more air permeable than the alpine. I have a Boreas which i'll check it against later. I like the fabric of the alpine start but the fit is weird around the neck & hood so I'm returning it. I need to put a cap on my windshirt collection anyway.

[Richard Nisley]

This update is a result of ground work done by both Ken Larson and Woubeir (from Europe). Ken provided information regarding his discussions with Schoeller Corporate and Black Diamond Corporate about Alpine Start fabric specs. Woubier provided information regarding the value of incorporating iClo comparisons to better understand windshirts.

Ken’s input, along with other forum members, is included in the following summary BD Alpine Start specifications:

Woubier’s input, incorporated into my BD Alpine Lab test results, is as follows:

[Paul Hatfield]

Thanks for taking the time to test the the Black Diamond Alpine Start and give us some hard numbers. According to your measurements, the Schoeller fabric used in the Black Diamond Alpine Start seems to expand the envelope of breathability vs. water resistance.

[Wim Depondt]

Hi Richard,

Thanks for taking out the time and energy to do this and previous tests. Invaluable information for hikers in need of a good windshirt.

So, the fabric is indeed polyester/elastane (and not nylon/elastane as provided on BD's website)?

Wim

[Paul Hatfield]

The tag on the Black Diamond Alpine Start indicates polyester/elastane. This is in disagreement with Black Diamond's web site.

The Scholler fabric in the Black Diamond Alpine Start is a 2-way stretch fabric. The orientation on the stretch is horizontal in the torso of the garment (This is in contrast to the Outdoor Research Ferrosi Hoody, which orients the stretch vertically.)

Via breath-testing side-by-side on new jackets, in my opinion, the Schoeller fabric has slightly higher air permeability than the Pertex Equilibrium of the Rab Alpine Jacket. This is in contrast to Richard's measurements on a new Black Diamond and *used* Rab.

If not using a helmet or hat, the brim of the Black Diamond hood needs to be rolled back. Also the hood does not want to turn with your head. The hood on the Rab Alpine Jacket is better sorted out, in my opinion.

The front neck area of the Black Diamond is on tight side when fully-zipped. It might not be comfortable if fully zipped. Zipped down 3 or 4 inches, it is fine for me.

The zipper of the Black Diamond works well and doesn't catch on the zipper flap. (The zipper on the Rab often catches on the zipper flap, at least just trying it out in the house.) What is the purpose of a zipper flap on a wind jacket anyway?

The Rab has a lot of extra fabric in the chest and torso for me. I suspect the MEC RD Windshell might be better fitting for me, though I haven't seen one in person.

Perhaps Rab should consider making their Alpine Jacket out of the Schoeller fabric.

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