Forum Index » Editor's Roundtable » Field Testing Air Permeable Waterproof-Breathable Fabric Technologies – Part 2: Are There Detectable Differences Under Real World Backpacking Conditions?


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Chris Townsend
(Christownsend) - MLife

Locale: Cairngorms National Park
Field Testing Air Permeable Waterproof-Breathable Fabric Technologies – Part 2: Are There Detectable Differences Under Real World Backpacking Conditions? on 10/26/2011 13:20:17 MDT Print View

Good test Will. I've not tried all these jackets but I have been using the Rab Neo Stretch since last February, when I used it on a wet two week Southern Upland Way hike, and two Active Shell jackets, the Berghaus Velum and Haglofs Endo, over the summer and autumn, which have both been wet here in the Scottish Highlands. I judge waterproof jackets on how comfortable they are when worn all day, as is not uncommon here. On backpacking trips they are often worn all day every day. The wet, windy and humid Scottish weather makes this a tough place for rain gear. The key is keeping comfortable, which means just warm enough and not too damp. Nothing I've used keeps me dry when moving but some fabrics are far better than others (and of course the clothing you wear underneath makes a big difference too - many people wear too much and then sweat, producing much condensation - that's why I said "just warm enough"). Without doing a direct comparative test like Will's I've found the least condensation in Neoshell and Active Shell garments, with eVent not far behind. All three also dry out from inside more quickly than alternatives. I can get quite damp from condensation in any of them when working hard however. But condensation is warm and rain is cold so the first is preferable.

All that said, when it's cold enough (below 40F for me) Paramo performs better than anything else.

Joseph Reeves
(Umnak)

Locale: Southeast Alaska
Re: rain on 10/26/2011 13:28:09 MDT Print View

Interesting and informative test on the one topic that I really struggle with; trying to stay dry in the rain.

Andrew Skurka nails it with his comment about accepting the rain. I've come to learn that if it going to be p*ss rain here, like it is from September to December I either wear non breathable Helly Hansen and sweat, or get by with an OR gore-tex pro jacket with the zipper system that Eric Chan illustrated above.

Dale Wambaugh
(dwambaugh) - MLife

Locale: Pacific Northwest
Re: Field Testing Air Permeable Waterproof-Breathable Fabric Technologies – Part 2: Are There Detectable Differences Under Real World Backpacking Conditions? on 10/26/2011 13:31:09 MDT Print View

Another excellent test of equipment with real data to compare. I'm glad to see the issue of how a backpack effects rain gear ventilation covered.

The side vents on the OR gear make a lot of sense. With just the front hem free, it allows air circulation between top and bottom. I rarely trap my rain shell completely under my belt, with the front draped up and over for more air. Hiking in moderate temperatures of mid-50F with light precip and high humidity is my challenge. There's nowhere for the sweat go to!

It would be interesting to see the results compared with a poncho and the same data tracking. DriDucks would have made an interesting product to include too.

Thanks for all the hard work and myth-busting!

Edited by dwambaugh on 10/26/2011 13:54:17 MDT.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Marketing departments gone wild on 10/26/2011 16:04:19 MDT Print View

> 2- The marketing pitch for WP/B fabrics hinges on a consumer's belief that they can
> actually stay dry when it's wet outside. My experience is that this is flawed
> expectation.

Right on Andrew!
This is pure marketing spin of the worst sort, and Gore are particularly at fault here for deliberately trying to deceive the public with their 'guaranteed to keep you dry' claim.

My solution in rain is a silnylon poncho and expect to get wet from condensation underneath. But it's warm-wet, not icy-cold-wet. And my pack is waterproof!

Cheers

Oliver Nissen
(olivernissen) - MLife

Locale: Yorkshire Dales
Very thought inspiring stuff on 10/26/2011 18:02:20 MDT Print View

Thanks for the hard work you've put into this, but I have to second Roman Vazhnov on picking up a number of minor issues that need consideration and add a few other points/corrections. I'll try to make this as brief as possible....

Roman rightly points out the importance of where the humidity sensor is placed in relation to zip openings. I used to own an Arc’teryx Alpha SV jacket, which proved to be useless protection from the cold in anything stronger than a breeze as its storm-flap-less pit-zips offered no resistance to wind penetration (but hey, great ‘breathability!’) On the opposite side of the coin, a big problem with zips is the amount of extra seam-tape they require which locally prevent moisture transfer out of the garment - if the jacket is closer fitting, this effect will be worsened as there isn’t as much air movement inside the jacket.

Roman points to other sets of factors to take into account - aspects of the fabric performance (aside from the membrane) and garment fit make a big difference to breathability and insulation. (Why, you may ask should we separate fabric performance from membrane performance? Well all the branded membranes are offered to brands with a range of different face fabrics, and sometimes different linings too. More on this a little later…) Anyway, here are my points about fabrics:

Firstly, garment fit coupled with fabric stiffness and weight has a noticeable effect. Stiff baggy shells (e.g. shells with laminated fleece linings) hold much of their surface away from the wearer, and with static folds of excess fabric, trap spaces of still air inside the garment - effective insulation. (This is partly why stiff heavy shells are popular in the sailing fraternity.) Of course more insulation = more heat stress = more sweating = humidity. It’d be very difficult to measure this effect, but it’d be interesting to hear if Will thinks this might have been a factor with any of the test pieces.

Still relating to fit, the second factor is garment coverage – how low is the hem and high is the collar? More coverage = more insulation and more area where sweating’s evapourative-heat-loss is hindered = more heat stress = etc. (you know the equation!)

Thirdly, the insulating effects of a shell may go further. If a shell is closer to equalising its temperature with outside cold it will promote more condensation on its lining which will reduce our humidity measurements (though not necessarily improve comfort over the long-run – which depends on what then happens to the condensation – my next point.) It’d be interesting to see the R-values (insulation) of the different text piece fabrics. (I really don’t know how much variation there would be and nor do I know how far this might affect condensation – can anyone enlighten me?)

Fourthly, if higher air-permeability allows wind to rapidly cool the jacket’s internal microclimate, then condensation and attendant higher conductivity and evaporation chill will occur deeper inside a layering system (if midlayers are worn - not in this test) as the dew point moves inwards. (Note that venting after building up a sweat will also have the same effect – so it’s best venting before you get all hot and sweaty in the first place!) This is only mitigated by the fact that as the jacket is so breathable, less humidity will have built up inside it in the first place. Of course this point is part of the common objection to air-permeable waterproofing – it’s not entirely windproof.

My fifth point is how shell linings aid comfort in a way not measured by this test – a good lining will absorb condensation or otherwise make it more acceptable (why 2.5L isn’t as comfortable as 3L). Maybe Chris Townsend’s experience with Neo and Active shells having less condensation than eVent is that they are faster at absorbing and spreading out condensation than the rather run-of-the-mill light grey tricot that lines eVent fabrics?

This brings me on to the sixth and final point. Point #4 in the article doesn't emphasise that any particular membrane will be laminated and sold with a wide range of different face fabrics all with their own varying levels of performance - it's not that one fabric is always mated to another membrane. I’ve seen suppliers’ own lab-test results and the same membrane will have vastly different MVT scores when laminated to different faces (sadly I’m not at liberty to quote figures). To sum it up, there is little consistency for the consumer to rely on and no marketing that one can take at face value - what's new?!

An aside… midlayers and insulated shell technologies can hinder moisture transfer in your layering system far more than the shells that might be worn on top of them. My Mtn Hardwear ‘monkeyman’ jacket is a bad offender. With ‘high-loft’ surfaces on inside and out, it is densest in the middle so capillary action doesn’t work in its favour. It seems to be particularly good at just holding moisture and getting claggy (unless I wear it exposed directly to the wind, in which event I may as well not wear it at all). Other bad offenders are synthetic fibre insulated garments (Primaloft etc) - two windproof layers with a thick still layer entrapped in a hydrophobic mat - all is not good on the moisture transfer front. Warm though! (I’d be curious to see how quilting shell and/or lining to Primaloft might vary breathability - a wind-flapped shell layer could help convect moist air through the otherwise inert fibre mat.)

Finally those (slighly anal) corrections I promised:
As Roman pointed out, GoreTex membranes generally aren’t air permeable (Their tent membranes are and perhaps Active Shell is too?!)

“A plain woven fabric without any membrane or coatings can be very breathable... but not water-resistant” - I dispute that. A dense weave/non-woven fibre mat + DWR, or Ventile can be highly water resistant.

“A polyurethane membrane requires two phase changes (vapor to liquid to vapor) to vent moisture” - true for hydrophilic PU membranes (and also that famous polyester-polyether block copolymer membrane- Sympatex), but there are also hydrophobic microporous PU membranes too. These act much like ePTFE. I suspect Neoshell is one of these and as I’ve hinted above, Gore’s Active shell maybe a combination of ePTFE + microporous PU, as opposed to their usual ePTFE + hydrophobic PU lamination, but I might be wrong?

There... I'm done! :)

Edited by olivernissen on 10/27/2011 15:57:29 MDT.

George Matthews
(gmatthews) - MLife
Re: Field Testing Air Permeable Waterproof-Breathable Fabric Technologies – Part 2: Are There Detectable Differences Under Real World Backpacking Conditions? on 10/26/2011 18:09:10 MDT Print View

Great article and great comments. Both make BPL worth the dimes.

eric chan
(bearbreeder) - F
Re: Re: Field Testing Air Permeable Waterproof-Breathable Fabric Technologies – Part 2: Are There Detectable Differences Under Real World Backpacking Conditions? on 10/26/2011 19:53:50 MDT Print View

The side vents on the OR gear make a lot of sense. With just the front hem free, it allows air circulation between top and bottom. I rarely trap my rain shell completely under my belt, with the front draped up and over for more air. Hiking in moderate temperatures of mid-50F with light precip and high humidity is my challenge. There's nowhere for the sweat go to!

dale ... for those conditions i heartily recommend OR's torso flo system

as long as you are wearing quick drying synth base layers, and not over dressing ... even the rain which gets through the open zips will dry fairly quickly with yr body heat pushing out the moisture ... or at least get less damp

the key with the OR system is that you can fully ventilate the sides so that it acts as somthing like a running jersey, or a poncho ... you can also open up the front different ways as it has a double zip ...

its also quite useful for high exertion as you can open it all up when moving, and then close it all up at stops ...

as with anything else you WILL get wet if it rains enough, but IMO ORs system allows enough ventilation and temperature control that you have many options ... and im a very sweaty pig ...

Warren Greer
(WarrenGreer) - F

Locale: SoCal
Extensive Effort on 10/26/2011 20:12:42 MDT Print View

Will, thanks for that. Now let the manufacturers come and analyze that. They probably know this stuff already, but now its more in the public domain. And it sure fly's in the face of all their outrageous claims.

Further, it just shows that this technology is in it's infancy and there's a very long way to go. Hopefully there'll be some significant break throughs in the next few years because of the attention that Will and BPL bring with these reports.

I would also like to know how DriDucks fits in here. It sure breaths much better than my Marmot Aegis.

Finally, rain jackets aren't just for rain. Many of us live in drier climates where we don't see much rain. We carry them just in case. But we also carry them to trap heat in the morning/evenings or to provide additional warmth in our sleep systems. Having a fabric that breaths well in those situations is also very attractive.

Samuel C. Farrington
(scfhome) - M

Locale: Chocorua NH, USA
Part 2 on 10/26/2011 20:21:11 MDT Print View

Thank you so much, Will, for this article. It is going to save me umpteens of $, and a lot of disappointment!

Just a couple points:

" ...fabrics such as event are not worth the extra $ ..." (posted above).
How funny that I reached just the opposite conclusion about eVent from your article.
Just goes to show we all look at things from different perspectives.

I am partially color blind, so much appreciated the notes that reviewed and explained the graphs. Made it all work for me.

The post about the absence of rain raises a good point. The quality of the outside DWR treatment probably plays a big role, and may explain why I'm wedded to my Patagonia Specter after years of hiking in the rain with wetter and heavier GTX.

So, in part 3 do you run on treadmill under an industrial strength shower nozzle? (Sorry, couldn't resist.)

Edited by scfhome on 10/26/2011 20:23:06 MDT.

Tom Kirchner
(ouzel) - MLife

Locale: Pacific Northwest/Sierra
Re: Re: Re: Field Testing Air Permeable Waterproof-Breathable Fabric Technologies – Part 2: Are There Detectable Differences Under Real World Backpacking Conditions? on 10/26/2011 20:24:42 MDT Print View

"The one material/jacket I would love to see added to this would the the lightest driducks or or rainshield 02 which gives surprisingly good performance, especially in view of cost."

+1 Particularly for trail hiking.

Tom Kirchner
(ouzel) - MLife

Locale: Pacific Northwest/Sierra
Re: Marketing departments gone wild on 10/26/2011 20:32:39 MDT Print View

" Backpackers need to get over this idea that you can be immune from your environment -- when it's wet, you should expect to get wet, because you will. It's much more fruitful to focus your attention on how you can minimize the effects of being wet."

A huge +1, as in staying warm.

Mark Handy
(mhandy)
quantitative versus subjective on 10/26/2011 20:57:27 MDT Print View

So do these numbers square with BPL's consistent opinion that eVent keeps one significantly drier? In particular, Will, did the humidity numbers square with your subjective experience of the jackets?

I am inclined to doubt the humidity numbers and trust the subjective opinions. Commenters have already mentioned the issue of the location of the hygrometer. Another hypothesis: There is some kind of steady-state effect that keeps the humidity inside the jacket pretty constant, despite real differences in how much moisture various jackets let out. In that case, the effect of increased expulsion of moisture might be found in the shirt, not in the air inside the jacket. Did your shirt feel less soggy in some jackets than in others?

If this idea seems right, here are two tests that might put numbers on the subjective impression that eVent is better than old-fashioned Gore-Tex: (1) wear the hygrometer inside your shirt, instead of inside the jacket, and see if there is a bigger humidity difference nearer your skin (which is what you care about, after all); (2) wear a water-absorbing shirt, like a heavy cotton T-shirt, and see if there is a significant difference in how wet it is, say, ten minutes after the end of the sustained uphill walk.

Mark

David Chenault
(DaveC) - BPL Staff - F

Locale: Crown of the Continent
WPB v. coated on 10/26/2011 22:13:19 MDT Print View

This spring I tested a coated shell (a packa) back to back to back against a PU and G-tex shell. This gave me a whole new appreciation of what breathability means, as the difference between the packa and the others was quite drastic over several hours of sustained hiking in the rain.

I'll gladly deal with current WPB tech. Now if we can just get manufacturers to take hood design more seriously.

Eric Blumensaadt
(Danepacker) - MLife

Locale: Mojave Desert
Undulating Hikes on 10/26/2011 23:25:50 MDT Print View

Thanks Will, for a very good review and clear, graphic charts.

Now I see why my REI Kimtah eVent parka has worked so well both as a wind jacket and as a rain parka.

MOST hikes are undulating and according to your charts and my own experience eVent seems to work in that situation of heating up and cooling down repeatedly.


P.S. (WPB STANDARDS) Is there SOME way we consumers in the hiking/backpacking community could pressure the WPB garment industry to publish "waterproof" and "breathability" figures based on INDUSTRY STANDARDS? Eddie Bauer does it with their B 200 WPB parka, why not everyone else?

Edited by Danepacker on 11/02/2011 12:02:22 MDT.

Mark Verber
(verber) - MLife

Locale: San Francisco Bay Area
Re: quantitative versus subjective on 10/27/2011 00:49:55 MDT Print View

Mark suggested:

> wear a water-absorbing shirt, like a heavy cotton T-shirt, and see if there is a significant difference
> in how wet it is, say, ten minutes after the end of the sustained uphill walk.

This was something that Alan Dixon did in 2001 and wrote up in the BPL article High Exertion Moisture Accumulation in Rain and Wind Shells

Richard Gless
(rgless) - MLife

Locale: San Francisco Bay Area
Field Testing Air Permeable Waterproof-Breathable Fabric Technologies – Part 2: Are There Detectable Differences Under Real World Backpacking Conditions? on 10/27/2011 01:02:16 MDT Print View

>"The one material/jacket I would love to see added to this would the the lightest driducks or or rainshield 02 which gives surprisingly good performance, especially in view of cost."

I agree. I would really like to see how this material does in comparison with the more expensive materials. In my limited experience it appears to do well.

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
DWR coating on 10/27/2011 08:20:36 MDT Print View

If the DWR coating wets out, then the WPB membrane quits working.

In that case, why even bother with the WPB membrane? Just get a good DWR.

Everyone talks about the technology behind WPB membranes. Maybe what's important is the DWR coating? What is the technology behind that?

I have noticed that with a DWR coating, if there is something that absorbs water touching the inside of the fabric, water will be wicked through the fabric into the absorbtive material. Maybe you need a DWR coating, and then a hydrophobic material inside?

Marco A. Sánchez
(marcoasn) - M

Locale: The fabulous Pyrenees
Re: Marketing departments gone wild on 10/27/2011 08:29:28 MDT Print View

A must-read about what to expect from rainwear:

FAQ - Rainwear - parkas and trousers, etc

Cheers

Steven Schaftlein
(sschaftlei) - MLife

Locale: Mid West
Re: Field Testing Air Permeable Waterproof-Breathable Fabric Technologies – Part 2: Are There Detectable Differences Under Real World Backpacking Conditions? on 10/27/2011 08:30:05 MDT Print View

Another well done article based on good science and practical experience. "Miracle Fibers" are only one part of maintaining comfort. Along with the proper choosing of insulating layers, toboggan hat, and neckie, the unzipping of the front of the jacket is a key method of controlling comfort, temperature, etc. A willingness to adjust all of the above helps a lot. (In colder weather I will add a layer when descending a long distance and remove a layer when ascending a long distance.)

Goretex was a great step forward when it first came out. It provided another option for individuals to choose. These new fibers with their ability to breath before temperature and humidity reach the level of "vapor" are definitely an improvement.
They provide additional options. Each person needs to discover and utilize what he or she finds most comfortable and affordable.

Wool, leather, canvas, and cotton were once the standard for outdoor clothing. Then nylon and other synthetic materials came along. Similar advances continue to be made in all aspects of outdoor equipment. Our menu is no longer limited to a few choices. We have an ever growing buffet of possibilities. We should not be afraid to taste the new recipes.

Chris Townsend
(Christownsend) - MLife

Locale: Cairngorms National Park
DWR treatment on 10/27/2011 09:40:21 MDT Print View

"If the DWR coating wets out, then the WPB membrane quits working.

In that case, why even bother with the WPB membrane? Just get a good DWR."

Not quite correct. When the DWR treatment wets out the WPB membrane doesn't breathe as well so condensation build-up inside is greater. But the WPB membrane remains waterproof. In most garments with just a good DWR you will get wet in heavy or prolonged rain (except with Paramo or similar two-layer garments. In dry areas with only occasional rain just a DWR treated garment may be fine, and will be more breathable than any waterproof, but in wetter places a fully waterproof is needed if you are going to be out in the rain for long.