William,

No single test type, such as breathability, will allow you to understand which is the BEST option for ultra-light backpacking. The problem is FAR more complex than what $50K of test equipment will answer.

BREATHABILITY
You said, “BPL needs to flip the market upside down and come up with an objective breathability test for WPB fabrics”. Roger correctly answered that there are many “standard” breathability tests. Natick labs believe that the DPMC is the most telling of the standard breathability test options. $50K MIGHT cover the cost of building and executing a DMPC test of the UL options. This test will tell you that eVENT (ePTFE) is best and the hydrophilic PU coatings, favored by UL backpackers for their light weight are the worst.

To really understand the true relevance of breathability tests also requires an understanding of metabolic rates, perspiration production, and vapor permeability requirements.

If you are selecting a bivy or protective garment to wear while sleeping, you only need a WVTR of ~600 g/24h/m2. Any DMPC tested material is generally adequate for this environment.

If you are selecting a protective garment to wear while sitting around camp, you need a WVTR of ~1,300 g/24h/m2. Any DMPC tested material is generally adequate for this environment.

If you are selecting a protective garment to wear while walking around the city, you need a WVTR of ~2,500 g/24h/m2. The top 50% of the DMPC tested garments are generally adequate for this environment.

If you are selecting a protective garment to wear while backpacking in the mountains (6 – 8 METS), you need a WVTR of ~8,000 – 10,000 g/24h/m2. The most breathable option, eVent, only provides ~5,000 g/24h/m2.

To not have WPB garment breathability limit your work output potential, it would have to have to be air porous with a rating of approximately 400 CFM (loosely woven cotton shirt and pants). The most breathable WPB, which is truly rain proof, is .84 CFM, to put this requirement in perspective. Once air permeability gets beyond this general area they are no longer rain proof.

RAIN
None of the standard breathability tests measure breathability in the rain. If you do a Vidybel (2 hour flex test in simulated rain) you will find out that the best and worst WPB options, from the breathability test, are reversed when it comes to leakage from light rain.

If you do a P. Salz test (1 hour in simulated rain without movement) you will find that the breathability of 2-layer eVent actually goes up, 3 layer eVent is only slightly reduced, and the hydrophilic PU coatings reduce their breathability to 19% of their dry value.

If you do a J.E. Ruckman test (1 -30 day simulated rain) you will find that the breathability of all garments varies dramatically based on temperature of the rain hitting them. You will discover that 5.6 mph wind combined with rain also further reduces the breathability of all WPB types. You will also discover that after 24 hours of simulated rain that eVent breathability drops approximately 10x and then stops breathing completely after 7 days. The hydrophilic PU has the same breathability as eVent after 24 hours and maintains this level of breathability through a 30 day test.

DURABILITY
If you conduct ISO 6330 Wet-Flex tests you will find out that PU garments wear out and leak in the range of 100 - 250 hours of use. In contrast, both eVent and Gore-Tex last more 500 hours before they begin to leak.

SUMMARY
No one test is adequate to evaluate WPB materials. Most people use WPB for lower MET activities and they periodically reactivate the DWR in a dryer; it works adequately for those environments. No WPB material is close to adequate for mountain backpacking in the rain. In other words, it is exactly as you postulated, "There just seemed to be a lot of things missing, unless the motto at BPL is all WPB suck which should be stated..."

Edited by richard295 on 06/01/2012 22:57:53 MDT.

Hi William

> Testing to see how waterproof something is shouldn't be as difficult.

There are several problems here, some of which Richard covered (very nicely too) in his posting:
What weather conditions do you need to handle?
What face fabrics do you want to include?
What period of prior use do you want to specify?
What damage and dirt will you allow on the fabric before testing?
What amount of flack do you want to handle from rival companies?

Each of these questions has a potentially infinite range of responses. One could spend a lifetime and a fortune trying to cover all of them completely. This may be summarised thus:

* How can you objectively test a range of different products on different days under different weather conditions on different people working at different rates and hope to get any scientific results?

But, out of this mess, we can reach a couple of conclusions very easily:
* There are no really good WP/B fabrics in existance.
* All WP/B products have very serious limitations.
* Everyone wants a slightly different combination of properties.
* You are guarranteed to get wet (to paraphrase Gore).

What is the point then of a SOTM report on rainwear? It reminds people of some commercial options and it reminds people of the range of problems, because some people keeping asking the totally unanswerable question of "what is the perfect rainwear?". Alternately, we could just say "Ain't no such thing", but that might be boring.

> what would you do with 50k toward developing an objective test?
Are you offering $50k? Seriously?

Cheers

I wonder how comfortable it would be to wear Paramo garments "while backpacking in the mountains" in the rain?

http://www.ukclimbing.com/forums/t.php?t=434540

> But, out of this mess, we can reach a couple of conclusions very easily:
* There are no really good WP/B fabrics in existance.
* All WP/B products have very serious limitations.
* Everyone wants a slightly different combination of properties.
* You are guarranteed to get wet (to paraphrase Gore).

So...

I have been using waterproof ponchos for years. I can vent them and they cover my upper legs. Also no pack cover or liner needed. Can also double as a shelter or occassional ground sheet if my foam pad isn't adequate for the ground. Great for an awning when resting during the heat of the day in deserts. Can also be used as a vapor barrier in my bag/quilt as an emergency measure. Once used a poncho as a solar still to collect water. They are inexpensive.

I have tried all sorts of rain gear and always go back to a poncho. I am done searching for the holy grail of rain wear, although I recently bought some cuben rain chaps that I haven't tested yet.

I have a different conclusion, not that I won't change my mind in the future

WPB isn't perfect but a little better than totally non breathable fabric when exercising

With a poncho, if it's windy, it blows around too much, and rain blows in. If I have a loose jacket, I can unzip front when it's not too windy and get benefits of poncho. Occasionally I pull my arms out of sleeves.

Worse points are shoulders and top of head where the fabric pushes against skin

If I quit exercising, then I'll dry out after a while with WPB, not with waterproof

Thank you both very much for your responses. I realize my comment about how BPL should devise a test might have been taken the wrong way and I apologize for that. I know it's not a novel idea, sorry if it came across like that.

So if there are physical limitations (of the fabrics) to achieving the breathability required, is there a test that could approximate the relative crappy-ness of a fabric for mountain use? Or are the 2 layer, 2.5 layer a 3 layer fabric all the same? I know there are some minor functional differences depending on the layers (ie proshell is more comfortable than precip, to me at least). Are all 2.5 layers the same?

I understand that each environment, metabolic rate, wear, etc will all affect the garment. It just seems like we didn't get any of that information in the report, which is why I was questioning it's value. I can also understand not wanting re-hash all this with each report, but if it's pretty much a fit guide to some pants, why not include measurements?

Does BPL have to worry about flack from companies? Or were you referring to if one of the manufacturers was designing the test?

Haha sorry Roger I don't have 50K to donate to the cause, just curious as to what you think a good test would be. Never know what could come of it.

Richard, could you please tell more about J.E. Ruckman test?
At first Event has full breathability (=1). After 24 hours it has 1/10 of full breathability. After 7 days it has 0 breathability.
Questions:
- after 24 hours hydrophilic PU has 1/10 of full breathability of Event? (And at first hydrophilic PU had, let's say 1/2 of full breathability of Event). Then it maintains 1/10 of breathability for 30 days? What happens after 30 days? No breathability too?
- What causes Event to stop transporting vapour after 7 days?
- Why does hydrophilic PU last longer?
- Is there some data for new hydrophobic PU membranes, for example Neoshell?
//excuse me for my english.

> Does BPL have to worry about flack from companies?
I think the question might be better worded as 'Does BPL worry about what reaction the companies might have if we are critical?'

I can tell you quite positively that the answer is NO. BPL does NOT worry. (That's one reason BPL does not carry the usual ads from companies: we are independent.)

Realistically, as long as we review the product, that seems to be enough. That gets Google hits.

Cheers

OK, nobody in UL backpacking likes to carry the "extra weight" of rainpants. That's a given, evidenced by all the alternative solutions like rain kilts, trash bags, bare legs, Cuben fabric rain chaps, etc.

My "forced" solution, for budgetary reasons, is Cabela's PacLite rainpants. Light "enough" at 15 oz. and very packable into their own hip pocket. They have protected me well in high Sierra and Rocky Mountain downpours. I got 'em on sale for $79. + shipping. I also have the companion Cabela's PacLite GTX parka at a great price as well.

THEN... last year I bought an REI Kimtah eVent parka, on sale, because it is the breathability of the parka that is really most important. Torsos seem to produce more "noticable" perspiration than legs. Plus parkas are used much more often than rainpants and I could justify the cost. (Even gearheads try to justify purchases!)

So with eVent parka and PacLite pants I have a fairly good WPB combo - light but not UL light, but durable AND within my budget.

P.S. Much like an earlier "REVIEW" of State-of-the-Market of mid cut boots this article is NOT subjective, and certainly not helpful as too few products were reviewed, let alone actually objectively tested.
BPL has put out some excellent test articles and reviews but the kind of chaff as seen in this article we can do without.

Edited by Danepacker on 06/11/2012 14:36:28 MDT.

Hi Jeffrey, Re your query, I'm in the same boat, in my case 6'4" and an inseam of 36" on pants. With hiking pants though, you'd normally not want them dragging, so I'd look for a 34" or 35" inseam. The only ones I've found that fit me well were from Arcteryx. The Alpha SL's use Paclite, are quoted at 9 oz. and come in a normal inseam which is 31" but also in a 34" inseam Tall. I had to look for Tall's for quite some time before I found them, so when I did find them, I bought two pairs (and haven't regretted it! Enjoy.