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

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 …

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.)

" 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.

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.

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

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?

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.

"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.

'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."}

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

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.

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.