Coffee filter breathability test on several wind shirt fabrics

Good work, Wim!

Did you use a Bunn coffee filter, by chance?

Hi Delmar,

"Did you use a Bunn coffee filter, by chance?"

Nope, I highly doubt that Bunn filters would be available in the EU(I live in Belgium). I just used el cheapo filters (supermarket house brand). But Richard Nisley noted that any brand of coffee filter should give similar results (although slightly different).

Wim

I believe Richard tested two brands filters in the thread referenced, Bunn and Trader Joe's. They were similar, so he concluded that any coffee filter is adequate for approximate testing. Maybe he's right, maybe coffee filters have uniform permeability the world over. PM me if you want me to send you a TJs filter for reference; I have those. I'll look around and see if I can find a Bunn.

So, I make a windshirt out of coffee filters, I doesn't matter what brand I use? :)

Wim,

Great contribution to the forum… thank you!

Of your available options, the RAB Alpine wind shirt is optimally balanced for UL backpacking in the mountains. The Pertex Equilibrium material may test differently in other garments.

Some supplementary information:

-There are both Pertex Equilibrium and Pertex Equilibrium Eco fabrics available
-There are (were) 8 different weights of Pertex Equilibrium available
-RAB specs their material, via ASTM D737, air permeability as 10 cc (SI). The equivalent ASTM D737 imperial value is 19.69 CFM. Many Internet references (see below) incorrectly state the air permeability as 10 CFM
-The lightest windshirt using a Pertex Equilibrium variant fabric is the Westcomb Crest hoody at 5 oz.

This information is invalid:

It's too bad the Rab Alpine Jacket weighs between 8 oz – 10 oz.

Richard,
can you give a range for the different Pertex-variants ? I ask because for Polartec Alpha, which Polartec claims is more breathable, at first notice they use the same fabrica as for the usual puffies.

Tom,

The Polartec business model for Alpha is to just sell the insulation, without any face-fabrics. Each manufacturer then laminates whatever face-fabrics they choose.

I haven't tested any of the Pertex Equilibrium variants.

That's exactly what I mean. Polartec only sells the Alpha-insulaton and most manufacturers use stuff like Microlight or Quantum. Now, I'm just curious if they use the same fabric as for their puffies or are they using (a lot) more breathable variants despite the fabric-name ?

What does the material used on the Rab Alpine jacket feel like? Is it basically a nylon?

It's interesting to see that Rab lists the air permeability for the Boreas at 8-10 CFM (or about 4-5cc) and for the Alpine jacket at 10cc. I wonder if you can tell the difference when hiking?

I currently have the Boreas and a Montane Mountain Star jacket. Montane lists the Mountain Star at 4.5cc max (not sure what the max part means) and I have not been able to tell any difference in breathability between the twos when hiking or walking. My medium weighs 6.8oz and seems to have a decent DWR, so maybe a lighter alternative for people.

Very nice tests.

I have the Rab Alpine Jacket and the Boreas.
When I did a quick personal breath test I thought the Boreas was slightly more breathable than the Alpine Jacket but I will do it again to check. The Boreas doesn't work so well for me because it gets wet/dries slower I think because of the higher lycra content.

The Alpine Jacket is the best wind jacket I have ever seen. The fabric is amazingly breathable but also doesn't hold any moisture, or hardly. I never really notice it. Apart from that the design of the jacket is great with good coverage and the typical superb Rab hood, vent mesh in pockets etc.

I would not want a lighter item for trading in these features. This is a garment that I typically do not take off, unlike my other lighter wind shirts (mainly Montbell Tachyon). So for wearing it the whole day I don't mind the weight. I wouldn't mind a pull-on non full zip version and smaller zips, and I wonder how it would be if it would have a full side pit-zip like the Arcteryx Alpha SL Pull-on – but as it is it's by far my favourite clothing item.

"What does the material used on the Rab Alpine jacket feel like? Is it basically a nylon?

It's interesting to see that Rab lists the air permeability for the Boreas at 8-10 CFM (or about 4-5cc) and for the Alpine jacket at 10cc. I wonder if you can tell the difference when hiking? "

The RAB Alpine certainly does not feel like the usual lightweight hard shell fabrics but has a more soft paper like fabric. Also, the fabric is not entirely flat, with very small dots on the inside (I suppose that might slightly help to (keep your base layer) dry when the shell wets out). The outside has a very small grid pattern, which probably contributes to its breathability.

With LOTS of imagination: think of the concepts of the Capeline 4 shirt fabric, recycled into a wind shirt.
– impression of the inside of the fabric: http://www.outdoorsmagic.com/reviews/jackets/softshell-jackets/rab-alpine-pull-on/gallery/37243.html?GalleryMediaItemId=9186#gallery
– impression of the outside of the fabric (the inside fabric on the right side this picture is NOT pertex quilibrium, but a tricot liner): 4.bp.blogspot.com/-f09Bx54WUVY/UdxDYSywvSI/AAAAAAAAFLQ/Q72l11yFE9M/s1600/pertex-equilibrium-vapour-rise-technologie.JPG

I haven’t been able to use the Alpine. It’s brand new and I am going to send it back to get it exchanged for a smaller model (fyi: I am 178cm, 79kg, male: the large is to baggy for me – I should have known: my RAB Tee & Boreas both are mediums).

Two close ups from Rab's Alpine Jacket (Pertex Equilibrium). Note that these are quite extreme close ups. When you wear it it just feels like smooth/flat fabric. Like Wim says though, I do think the small grid pattern adds to the breathability.

Thanks for the description and pictures. That raised grid pattern is cool for a shell fabric.

I've also been searching for a wind shell and layering system I can wear all day and I'm glad to see it can be done.

I apologize if I'm being dense here …

Does CFM mean cubic feet per minute as I've been assuming? If so, shouldn't there be additional units specified … like area maybe?

Jim,

Yes, CFM is the abbreviation for cubic feet per minute. Regarding area, the third implied term is /ft2.

Per section 11.1 of ASTM D737:

"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."

"I've also been searching for a wind shell and layering system I can wear all day and I'm glad to see it can be done."

This is the closest I have found. Depends of course on climate and activity context. I can't wear this in the hot very humid summer or when going very hard in 20~25˚C.

But yes, with the right base layer, this is the wind shirt that I can almost wear all day, all the time.
Compared to the Boreas you don't feel it as much when your back does get wet from sweat. I would have that quite often. I don't with the Alpine Jacket. But I don't really know if the Boreas, or the Alpine Jacket is actually slightly warmer (but better venting) while wearing it. In the end though, the Alpine Jacket works better for me.

Anyway, can highly recommend trying one out to see if it works for you.

Thank you Richard, I was expecting that there'd be something about area there … just wasn't sure what the units would be since we're talking about fabric … where more than one units of area is used.

followup question … from what I've read, a Frazier test machine is capable of measuring at different pressure differences across the fabric. I'm guessing that a fabric's CFM is different at different pressure diffs. The Frazier operates via vacuum rather than pressurized air so the possible range would be limited to 0

Good thread Wim. I have some updates on windshirts I need to put together soon.

Wim,

Could you elaborate a bit on how you use the filters?

Do you suck through them and then suck through the garment and keep adding filters until you subjectively think they are about the same?

Do you plug your nose when sucking?

Hi Daryl

"Do you suck through them and then suck through the garment and keep adding filters until you subjectively think they are about the same?"

Yep.

"Do you plug your nose when sucking?"

Good point. No, I did not plug my nose. But I just tested my breathing anatomy: it doesn't affect the 'sucking resistance' (but that's just me).

Wim

"Good thread Wim. I have some updates on windshirts I need to put together soon."

here is an idea: a kickstarter money collection to finance the airfare for David to team up with Richard Nisley for a State of the Market update on windshirts. Fair chance that might end up in the best BPL article in years.

Oh, we could do the same for Amy Lauterbach to finance a couple of RTW-tickets, in return for a dozen of her state of the art trip reports :-)

> "Do you plug your nose when sucking?"

I think it's important to get a good air seal around mouth and nose when sucking in air. Think of how a respirator fits. I make a (sort of) diamond shape with my fingers that seals around nose and mouth, then pull in as much air as I can. While my nose isn't obstructed, it isn't really used, either. Air goes in the mouth much faster so the nose just hangs out and watches the show.