Field Testing Air Permeable Waterproof-Breathable Fabric Technologies – Part 2: Are There Detectable Differences Under Real World Backpacking Conditions?

[Addie Bedford]

Companion forum thread to:

Field Testing Air Permeable Waterproof-Breathable Fabric Technologies – Part 2: Are There Detectable Differences Under Real World Backpacking Conditions?

[George Matthews]

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

[James holden]

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]

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.

[Sam Farrington]

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.)

[Anonymous]

"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.

[Anonymous]

" 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]

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]

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]

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?

[Mark Verber]

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]

>"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]

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]

A must-read about what to expect from rainwear:

FAQ – Rainwear – parkas and trousers, etc

Cheers

[Steven Schaftlein]

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]

"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.

[Diplomatic Mike]

"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."

A windshirt would be just as good, if not better, in those circumstances.

[Greg Letts]

Thanks for the detailed report. It verifies a similar conclusion I had come to after years of wearing Paclite and switching to an eVent jacket last year. I could definitely feel almost a cooling effect inside the eVent piece.

The point about darker colors changing performance deserves more attention at retail.

[Dale Wambaugh]

'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.'

"A windshirt would be just as good, if not better, in those circumstances."

I've sat on that teeter-totter so many times with clothing selection (or gear selection in general). If I were going to take the absolute minimum number of garments, a rain shell trumps a windshirt for handling harsher conditions. It is an easier choice if the forecast is for rain– the windshirt can stay home. The real quandary is whether you should march off into the backcountry with no rain shell if the weather is good. IMHO, that is where a DriDucks jacket comes into play.

Of course what everyone wants is a 4oz rain shell that breathes like a windshirt. {up music, Jimmy Cricket singing "Wish Upon a Star."}

[Diplomatic Mike]

I was simply replying to Warrens post, Dale.
Due to the unpredictability of the Scottish weather, i always carry a rain shell. I always carry a wind shell too. As Chris posted earlier, being damp in Scotland is usually a fact of life. Staying comfortably damp is the ideal.
I try to wear my rain shell as little as possible, and the windshell is worn on nearly every trek i'm on.
The only time i leave the windshell at home, is if i'm wearing Paramo in winter. My Aspira smock goes on at the start of the day, and stays on.

[James holden]

im sure not too many people here are fans of mister gryllls

there was however this one episode where they simulated hard windblown rain and bear did his best to survive it overnight under a tree branch shelter … they used a heat camera to record his temps … he was wearing no rain gear, just DWR and standard outdoor clothes

he basically went hypothermic in short order

now you may think hes a showman or "fake" … but theres no denying that he is a very fit and mentally strong person, more so than the majority on this site

if theres only one shell later i NEED to bring … its a waterproof

[Dale Wambaugh]

"im sure not too many people here are fans of mister gryllls"

Jeez, Eric, that is like going to the Cable Guy for computer support ;) I value your experience and opinion far more than the PT Barnum of Survival!

If you want to get wet and cold, the west coast of Canada is a good place to start, seconded by my climate 100 miles south. Rain gear is mandatory. I have allowed myself to take a DriDucks UL poncho when going on day hikes on August; the rest of the time, I'm ready for a deluge– or 24 hours of drizzle and wet brush.

[Buck Nelson]

Thanks for all the hard work on the testing.

Finally, rain jackets aren't just for rain.
Absolutely. Usually when I'm wearing rain gear it's NOT raining hard. I too am usually wearing it for a wind shell, for warmth, or even while doing laundry on a long hike. A good breathable will do these jobs as well as serving as rain gear.

…it is inevitable that sweat will condense on the inside of the shell (which is cooled by the outside ambient temp). Some mistakenly think this condensation comes from rain leaking in." I agree.

I also agree that it's important to accept certain discomforts that are unavoidable, like a certain amount of wetness when it's really rainy, but the gear we use and how we use it can make a big difference.

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."

I agree.

Mark referenced this article: High Exertion Moisture Accumulation in Rain and Wind Shells

In that test the breathable shell resulted in 6 oz. of sweat in the base layer, and non-breathable, 10 oz. I consider that to be significant difference in comfort. Since this forum is all about lightweight backpacking, carrying an extra 4 oz. of sweat, and presumably 4 more oz of water to replace that sweat, is worth considering.

[Diplomatic Mike]

Another thing to think about.
Like many on here, i don't carry spare clothing (apart from an insulating layer), and sleep in what i am wearing. I include my clothing as part of my sleeping system. If i allow myself to get more than damp, i could be in for a cold night.
I realise that this probably sounds stupid to folk who hike in dry climates.

[Oliver Nissen]

Finally fully updated the comments I posted earlier. I went on a bit eh!?

Conversation does seem always to go back to what is best practice… and everyone reverts to their anecdotes. As I'd suggested before, I'd like to see more hard data being gathered to give us a better idea of what's going on.

The question that vexes me the most regards the wideish range of temperatures recorded inside the jackets. Is that purely caused by lower breathability putting greater heat-stress on Will, or do some of the jackets naturally have higher internal convection, radiative heat transfer, etc. (in the ways I suggested in my previous comments), or are other factors at work I've missed out?

Without improved understanding of what's going on fabrics and membranes might get better but product design isn't.

[Author]

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