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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Roman Vazhnov
(joarr) - MLife

Locale: Russia
do we need WPB on 10/28/2011 06:33:43 MDT Print View

As everybody knows here, current WPB technologies are not perfect. Nevertheless today practically only WPB (and may be Paramo garments) provides acceptable function balance in certain areas. Of course we can use silnylon ponchos in lightweight backpacking (i use poncho too), but there are circumstances when we can not. For example mountaineering, canyoning, kayaking, biking. And of course there are backpackers who simply don't like to use ponchos. So it is good to know what WPB technlogy is better. And i think that the main focus of this article is to compare membranes and not to make claim that they all are crap. Besides, technologies are not standing still, progress is good.
It would be interesting for me to make this test with really breathable soft\wind shells (something like Dryskin or Pertex equilibrium) and with Paramo. Big thanks again, BPL, i can't buy all such jackets to do the tests by myself :) Though it would be fun.

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: leaky membranes on 10/28/2011 09:05:24 MDT Print View

Maybe it doesn't matter whether it leaks or it's sweat

If it's raining, I'll get wet

Plan B is to wear as little as possible, then when I quit hiking it will quickly dry out

I have found eVent and GoreTex to dry pretty quickly when I get out of rain and quit hiking

Ayumi Obinata
(plassy) - F
Lab Test on 10/28/2011 09:48:48 MDT Print View

This is one of the most interesting WPB test I've ever seen. It's a great start to decipher this voodoo technologies.

As Oliver commented, I also think the test is not perfect, but it seems like there is no scientifically perfect method to test WPB jacket so far anyway. Since the temp and humidity is probably not only affected by membrane by itself but also affected by zipper, size and length (also as Oliver mentioned), and the design philosophy of each jacket seems to be a bit different each other, so I would like to see the pure lab test result of each membrane performance exactly in the same lab condition, although the question is what kind of condition is more practical for lab test.

I also would like to see the lab test result of the endurance of DWR and the zipper/seam leakage of the major players.

Edited by plassy on 10/28/2011 09:59:39 MDT.

Dave U
(FamilyGuy) - F

Locale: Rockies
Re: Re: leaky membranes on 10/28/2011 10:29:08 MDT Print View

"Maybe it doesn't matter whether it leaks or it's sweat

If it's raining, I'll get wet"

There are two types of wet. A warm wet, and a really cold wet. Which do you prefer?

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: leaky membranes on 10/28/2011 11:26:57 MDT Print View

I think the amount of water is so small that the BTUs it takes to heat it up are infintesimal, so it doesn't matter whether it's sweat or rain water.

It takes 1150 BTU/lb to evaporate water from 32F

It takes (85-32) = 53 BTU/lb to heat water from 32F (assuming your rain water is 32F just for example) to 85F (which is what I've measured my skin temperature when I'm cold).

Then it takes 1097 BTU/lb to evaporate water from 85F.

So it takes about 20 times as much heat to dry out your clothes, than to heat up them up from cold rain water.

Conclusion - I don't think it makes much difference whether your clothes get wet from sweat or rain, but drying them out with your body heat will make you cold.

Diplomatic Mike
(MikefaeDundee)

Locale: Under a bush in Scotland
Warm'n wet. on 10/28/2011 11:59:04 MDT Print View

I don't think Dave was commenting on drying clothes. He was simply saying it is more comfortable to be warm and damp, than cold and damp, whilst actually hiking.

And safer.

eric chan
(bearbreeder) - F - M
wet on 10/28/2011 12:04:49 MDT Print View

if yr moving youll heat up quickly anyways

as jerry points out ... its when yr stopped or moving at a very slow pace when yr effed ... the evaporative cooling really takes effect

Dave U
(FamilyGuy) - F

Locale: Rockies
Re: wet on 10/28/2011 12:12:55 MDT Print View

Yes - Mike simplified what I was trying to say.

I disagree that the net effect is the same. Having been in some incredibly cold rain in temps close to freezing, I would much prefer a little bit of warm sweat to deal with. I would have a base layer on wicking up the sweat and although it is always a challenge to maintain core temps in such conditions, the temperature difference between the sweat and cold rain would be noticeable and the net negative effect on your core temperature would be greater. Any sort of arm chair science aside (and I say this in good humor), my experience suggests otherwise.

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: Re: wet on 10/28/2011 12:17:42 MDT Print View

I'll have to weigh my clothes when damp and calculate how many BTUs required

And compare that to BTUs required to stay warm

Are you calling me an arm chair scientist? Well, I am sitting on a couch...

Dave U
(FamilyGuy) - F

Locale: Rockies
Re: Re: Re: wet on 10/28/2011 12:29:08 MDT Print View

I am going to edit that because it didn't come out right. I am the arm chair scientist. And a bad one at that. I can only go by my experience.

Diplomatic Mike
(MikefaeDundee)

Locale: Under a bush in Scotland
Wet on 10/28/2011 12:37:11 MDT Print View

Seriously, hiking in near freezing rain is one of the most difficult conditions a hiker can face. Unless you have dealt with conditions like that for days (weeks) on end, it can be difficult to imagine. A oouple of times in the past i've nearly went down with hypothermia. Luckily i wasn't hiking solo at the time. I've had US family come here on vacation, and they have struggled with the weather. I guess folk from the NW of the US and Canada get the same conditions.
Here in Scotland, we do get the occasional high pressure zone in winter. Temps can drop to minus 29C, and the weather is clear and dry. It is pretty simple to deal with conditions like that.

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: wet on 10/28/2011 12:59:39 MDT Print View

"I am going to edit that because it didn't come out right. I am the arm chair scientist. And a bad one at that. I can only go by my experience."

Don't worry about it, you didn't say anything offensive : )

Anyway, not possible to unring a bell.

Dale Wambaugh
(dwambaugh) - MLife

Locale: Pacific Northwest
Re: Re: Re: wet on 10/28/2011 13:12:09 MDT Print View

It seems to be a consensus that there is no magic with rain shells. It looks similar to waterproof shoes to me, with the industry leaning heavily to the marketing hype.

Okay, assume you will get wet under your rain shell. You stop hiking and there you stand, it is 45F and you are tired and wet and starting to get chilled. Assuming that it isn't pouring, you get a dry layer out of your pack.... but UL principles lean to not carrying spares, or mid layers that might be base-layer substitutes. Oops! Many UL gear lists would have something like a Thermawrap or a light down sweater for insulation, with no spare base layer. I don't like that idea.

This is one of those scenarios where I think light fleece or other stretchy synthetic mid-layers are great. Power Stretch is my favorite, but there are tons of options, from basic 100w fleece to R1, Capilene 2/3/4 and so on. If I have stopped and find my base layer beyond redemption and I am cold, peeling and using my mid-layer for a long stop or camp would be my plan. The base layer might dry if I can get it under cover and a breeze, or a little warmth off a fire if possible. If it isn't soaked it will dry from my body heat-- if I don't get too cold trying to do that. Having a second base layer might be in the works too.

My point is that the rest of your clothing should assume that your rain gear isn't going to keep you completely dry, particularly in those scenarios where you are exposed to hours of cold drizzle and high humidity. Remember that long-term cold drizzle equals no direct sun, perhaps for days, so there is little opportunity for drying anything.

What is your solution?


Typical PNW weather: Lake Annette, Washington, July 4, 2010, 2PM PDT, elevation 3600', 49F, 95% humidity. There was a heavy rainfall a couple hours later, followed with hours of light drizzle and cold air from the snow fields above.
Cascade un-sun

Dale Wambaugh
(dwambaugh) - MLife

Locale: Pacific Northwest
Re: Wet on 10/28/2011 13:18:20 MDT Print View

Mike Reid wrote about Scotland: "I guess folk from the NW of the US and Canada get the same conditions."

Aye, it is a cool, dewy wonderland :) I think the Scots have more exposed conditions, whereas I can often hide in the trees. You must need some tough tents in Scotland!

Edited by dwambaugh on 10/28/2011 13:19:55 MDT.

David Olsen
(oware)

Locale: Steptoe Butte
Re: Re: Re: Re: wet on 10/28/2011 13:20:07 MDT Print View

What is your solution?


Typical PNW weather: Lake Annette, Washington, July 4, 2010, 2PM PDT, elevation 3600', 49F, 95% humidity. There was a heavy rainfall a couple hours later, followed with hours of light drizzle and cold air from the snow fields above.

After hiking is done?

1. Put up tarp

2. Change base layer and add other layers over.

3. Start stove or fire

4. Eat, and drink hot drinks.

Diplomatic Mike
(MikefaeDundee)

Locale: Under a bush in Scotland
Wet again on 10/28/2011 13:25:45 MDT Print View

Good post Dale.
I often read on the forum about folk getting wet, then drying their gear later. Sometimes i have to laugh! How do you dry your gear in continuous rain?
Fleece is hardly mentioned on here, but it is a mainstay of a Scots hiking gear. It doesn't absorb water, and it doesn't collapse when wet.

Dale Wambaugh
(dwambaugh) - MLife

Locale: Pacific Northwest
Re: Wet again and fleece on 10/28/2011 13:33:36 MDT Print View

Same with sleeping gear-- people writing about laying their down bag out to dry on a break. HAH!

Fleece (aka pile) was developed for North Sea fishermen to wear-- under non-breathable rain gear too. It is a mainstay of NW hikers as well. The weight isn't so bad, but the bulk is a pain.

Diplomatic Mike
(MikefaeDundee)

Locale: Under a bush in Scotland
Fleece on 10/28/2011 13:42:51 MDT Print View

Fleece was actually developed for North Sea oil workers to cope with the wet/cold. Probably because it was cheap. Fishermen used to supply the stand-by safety boats, and wore them too. I used to work on the North Sea oil rigs, and was very popular amongst my hiking friends. :)
It was originally only available in a dark blue colour. I assume that was the colour it came out in 'the mix'.

Diplomatic Mike
(MikefaeDundee)

Locale: Under a bush in Scotland
Fleece and beer on 10/28/2011 13:45:37 MDT Print View

My apologies for drifting the thread.
My excuse is the time difference. I've had a couple of beers. )

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: Re: Wet again and fleece on 10/28/2011 13:50:10 MDT Print View

"What is your solution?"

I have hiked in the PNW many times where I was somewhat wet after hiking - worst case is 32F and raining (and windy).

Wear base layer and eVent jacket while hiking that get somewhat wet inside.

Get tent up. Get inside. I'm pretty dry within one hour, during which time I have residual heat which keeps me somewhat warm. Also, I'm still moving around setting stuff up, eating. At some point put on insulated vest, hopefully my other stuff isn't too wet at that point.