Waterproof-Breathable Technologies

A synthetic sweater and a poncho are hard to beat – weight wise at least. In most cases, they will be lighter than any rain jacket & fleece combination. But I think there still remains a market for a good, waterproof-breathable rain jacket – storm protection while mountain climbing comes to mind as an obvious application.

As for nothing breathing at a humidity of 100%, this is where eVENT comes in and does its thing. Because it can actually move water vapor as a gas, and because gas movement depends on a difference in vapor pressure, not only humidity, eVENT will breathe even when humidity levels both inside and outside the jacket are 100%, because there is a vapor pressure gradient created by the differential temperature across the shell – warm inside and cool outside.

The solid state diffusion of water, as what happens in a Gore or monolithic PU membrane, may be less sensitive to vapor pressure gradients and more sensitive to humidity gradients, and this may be one reason why an eVENT shell, based on my experience, keeps you drier when outside humidity is 100%.

This makes sense out of the bewildering array of factors presented to us by the industry hype.

Do you currently feel that under the conditions you describe that the increased transfer of eVent will outweigh the downside factors of increased heat retention, increase in sweating, and reduced transfer (as compared to dry skin extreme types of materials).

What might an eVent poncho tarp that could be transformed into a closer fit in wind?

First, an excellent article! Very impressed and I certainly didn’t know that I needed to know that much regarding the various fabrics. My question is why manufacturers don’t compensate for fabric downsides with better venting ideas??

Popular wisdom says that saturated outer fabrics (ie where the DWR finish has worn off) don’t breathe at all well. DWR treatments seem more durable than they once were, but I still use Nikwax or Granger’s treatments once in a while to restore water repellancy. Do the different WP/B fabrics differ much in performance once completely wetted out?

Yes. It is impossible for me to maintain a temperate micro-climate without vents. Deep front zips can be left wide open when the wind is blowing rain on to my back. A lot of sweat exits the jacket when I do this.

Also, deep vents allow garments to be cut close, which cuts down on flapping. Flapping is becoming a real problem as fabrics become thinner and softer.

Best wishes, John

First of all, great article! Being a rather unscientific type, I did manage to get a lot out of it.

I enjoyed the matter of fact summarizations. Combined with the theory, tests results and extended discussions of the various fabrics I find that it helps me to be a more educated consumer.

I do have one comment and request. The article was discussing almost in it’s entirety to the breathable aspect of the various materials. Dare I say, the inside out of it all.

I would, most certainly, have enjoyed a more detailed discussion regarding the Waterproof-ablity of these fabrics as well. For example the references to “x psi” with respect to water pressure a given fabric could sustain before the fabric becomes saturated from the outside in.

The fact and fiction of it all.

How does that relate to real world experiences.

What other metrics are available to aid in intelligent evaluation of the various material’s Waterproofing qualities?

i.e. I’m in a bivy constructed of Epic and I am tarpless and in a raging thunderstorm, What can one expect? What if it was eVent, or GoreTex or even TODD-TEX…etc?

I am particularly interested in comparing eVent and Epic from the W/P side of things.

Regards,
Ronnie

I’m still interested in Paramo fabric; they claim theirs is not only waterproof and breathable, but will also transport liquid water from the inside to the outside.

i read frecuently that there is no gore jackets under 12 oz…. well i have a seam-sealed, hooded, full zippered jacket and weights in size m 275g real(my scale) grams (9.6 oz) made by sweden brand Haglofs (haglofs LIM ultimate jacket Berghaus has the paclite smock (half zipered)under 10 oz too and a full jacket (paclite jacket) under 350 grams ( really long, full zippered ventilated and good hood…)

Some months ago I read an interesting “practical in field” comparative about event and paclite that is really interesting

http://www.outdoorsmagic.com/news/article/mps/UAN/1879/V/1/SP/

carlos fernandez……… spain

I just wonder how the above fabrics compare with the performance of the fabric reviewed in this report?

I am interested in comparing the least breathable windbreakers with the most breathable waterproof/breathable rainjackets. It seems that the gap is narrowing. Wild Things makes a wind breaker out of Epic which is less breathable than eVent. Many people have used Gore Activent as a windbreake–although I thought it made a better rain jacket. Glen Van Peski seems to use a 3M Propore jacket as a combination rain jacket/ wind breaker, if I am understanding his list correctly.

I think a graph comparing the highly calendered microfibers used by GoLite, Marmot, Patagonia and others, with eVent and Entrant GIIXT might be suprising.

Ryan Potterton

In a few of our recent Outdoor Retailer Dispatches (http://www.backpackinglight.com/cgi-bin/backpackinglight.com/outdoor_retailer_news.html) we reported on the coming availability of two new eVENT shells – both in the 10 oz range – by Integral Designs (due out in 4 weeks) and one by Montane (due out Spring 2005). And, don’t forget 6-7 oz waterproof breathable shells from Patagonia and Montane, and a sub-8-oz shell coming from Outdoor Research…

Considering that full zip, hooded wind shirts range 3-6 ounces, and that WPB technology will continue to evolve, let’s consider the scenario where a wind shirt weighs the same as a rain jacket, then…will this change anyone’s clothing gear list? Will you ditch the wind shirt in lieu of a highly breathable jacket made of eVENT? Will those of you (us!) that historically use wind shirts and ponchos sneak a 3-4-5-6 oz rain jacket in there now?

Yes, I would definitely consider ditching my windshirt, but, while Integral Designs has taken a good step, why not at least add some pit zips (even if they are short)? Yes, I know they add some weight, but the gain in ventilation capability far outweighs the little extra weight. I generate alot of heat while hiking, and ventilation is critical to my moisture management and temperature regulation. If they’d added pit zips, THEN they would have made a jacket that I’d consider buying as my single wind/wp garment. So close, too bad they didn’t get it right. So, I’ll have to wait until they (or one of their competitors) make one that meets my needs. I was hoping it would be this one—so, yes, I’m disappointed. As a business person, it is always curious to me why a producer introduces a new product that is short of its capabilities.

Bryan, you have a point in that an ID eVENT Jacket with pit zips just might be the ticket to ditch the windshirt, at least in cold conditions. There is still quite a breathability gap between eVENT, and say, Quantum, but it’s small enough to make one think a little harder about it.

I just may hack up an ID jacket, put some monster pit zips in it, and see what happens. It will cost me an ounce, but if I’m saving three…

Ryan,

Let me know if you do that. In the meantime, do you have someone at ID you could encourage to add pit zips. As I said, it is a shame they didn’t get it right this time. Someone else will, and ID will have lost the advantage of being first.

My guess is they wanted to have the “lightest.” While there is marketing advantage to that moniker, I’ll bet that pit zips would have produced more sales in the long term. I’ll not buy the coat without them, and I’ll bet others won’t either.

Great article,
but as Ronnie Cusmano mentioned earlier, it only focuses on the B side. More info on the WP should be interesting also.
Kind of related do this, I was wondering what the real difference is in technology between GTX XCR and GTX Paclite ? Both are Gore products so based on PTFE-PU technology. But while XCR has an RET of 5-6, Paclite has an RET of 4, while XCR has an hydrostatic head of 80.000 mm, paclite ‘only’ has 30.000 mm. Why is this ? AFAIK, the obvious difference is that paclite uses a carbon layer instead of a liner and that the outer fabrics are usually lighter. But I would be very surprised that this explains the difference in both breathability and waterproofness. So how then can these differences be explained ?

as you noted, our interest is in the b of wp/b fabrics. for folks not being sprayed by firehoses most wp/b fabris are plenty wp :)whether it’s 80.000 mm or 30.000 mm it isn’t going to leak any appreciable amount in the field. you’ll likely see more leakage from construction such as seams, zippers, hoods, pockets, vents etc. thus our focus on the b where there are discernable field performance differences.

without contacting gore engineers directly i couldn’t give a definative answer. one guess is that the ptfe layer on the xcr may be thicker and therefore create a greater pressure head. it’s also possible that the pu membrane on the xcr may be thicker with similar results. possibly both contribute to the final pressure head difference.

also i don’t know where you got your rets from: but in the range of 4,5 or 6 (or 40, 50 and 60 us) it makes little difference. unless you use very precise equipment (most aren’t) the sweating hot plate test can’t resolve these ‘minor’ differences in breathablity. the test wasn’t designed to measure fabrics in this super breathable range. nor would these b differences be discernable in the field. one explanation: possibly the carbon protective layer partially blocks some breathabilty of the paclite membrane while the tricot liner on the xcr s ‘completely’ breathable. again without talking to gore engineers i couldn’t give a definative answer.

a few years ago i would have agreed that all wp/b jackets needed pit zips. with the new 3-5 oz water-resistant windshirts, i’m not so sure.

with the use of a very light and water resistant windshirt like a marmot chinook or a montane speed lite with shield i can get by in moderate or intermittent precipitation.

by the time i am ready to put on my ‘real’ rain jacket it is is either wet and/or cold enough that i am unlikely to use the pit zips, especially it it as breathable as eVENT.

for now the combination of a windshirt (or even the new Montane 1.9 oz wind vest) and eVENT jacket seems close to ideal for me and i’m not missing the pit zips.

guess it depends on how comforatable you are with the softshell technique of using a windshirt for moderate precipitation. if you buy in to it, you can probably get by without the pit zips. if you feel you need a jacket for even light rain in warm conditions then you’d probably be happier with pit zips.

hi-
although designed for cycling, Gill offers an eVENT jacket (the Adrenaline model) with pitzips-the only eVENT jacket w/ pits I’ve come across. Although no hood, this jacket otherwise might work as a “crossover” for activities like X-C skiing
tom

(wt listed at 387 gm’s)

We are awere of the Adrenaline jacket have tried a couple of times to get Gill to particpate in our review program. They have some trepidation since it is a cycling jacket and we are a backpacking publication. It would indeed be an excellent choice if used in combination with a had like the seattle sombrero.

Although as I pointed out earlier the windshirt and non-pit eVENT combo may have more utility for those that are comfortable with softshell tecniques for moderate precipitation.

Alan, I agree that initially differences in wp don’t matter. But doesn’t this play a role in the long term durability. I mean, eVent seems to be much more breathable than any of the Gore technolgies. But what about durability. I once asked the guys at Arc’teryx, a brand which is generally aknowledged to be innovative and looking for the highest performing technologies, why they weren’t considering eVent. They told me they tested the technology but they found it not durable enough (propably commercial reasons played an important role too). Tests with tent fabrics have shown that some loose up to half of their hydrostatic head in a period of just 6 months. I can imagine that this can work in the same way for wp/b technogies.

OK. First, eVENT is a newcomer and until very recently it’s been used limited ways in very expensive equipment—mostly climbing tents, heavy duty climbing jackets, and specialized climbing bivy sacks. Integral Designs has been an innovator with eVENT in North America. From all these applications, I haven’t heard anything negative about the durability of eVENT. All I’ve heard is raves about its breathability. As noted earlier, its high performance at low humidity levels is ideal for use in tents and bivys.

As eVENT enters into the more mainstream market with proletariat designed and priced gear like ID’s eVENT Jacket, Gaiters, etc (Montane too will likely enter with a backpacking/general use style jacket and pants this spring) we’ll see a lot more field use and abuse of the fabric. This may provide more information on the long term performance of eVENT. With 3 layer eVENT in the weight range of 2.5 layer PackLite, one might assume that eVENT may have the durability edge in the 8 to 10 oz jacket range.

For the time being I’d be skeptical of high end competing manufacturer’s that are heavily vested with WL Gore. As you point out this is hardly an unbiased opinion.

Also I am not one to get overly concerned about ‘minor’ leakage in either tents or shells. (Not implying in any way that eVENT leaks!) I use a BD first light with EPIC fabric. It is not entirely waterproof but works well enough for my purposes even if it does ‘leak’ a bit in sustained downpours. The fast pitching and stability of the freestanding wedge tent, its breathability, and its 2 kilo weight, more than make up for a low pressure head of the fabric. JMO.

For the time being, the combination of a light windshirt/vest and the eVENT Jacket is the bee’s knees IMO.

An alternative eVENT jacket with pit zips is the Rab Latok Alpine jacket (www.rab.uk.com, Quantum range).

Just looked at RAB’s website. Unless I’m missing something, this jacket does not have pit zips. Maybe the heavier version does.

It appears to have features similar to the ID eVENT jacket, possibly a nicer hood, but weighs about 75% more. 440g vs. 250g.

You’re absolutely right. How did I miss that ?
Following brands have eVENT with venting options but they’re not really light:
http://www.klattermusen.se/eng/products/index.shtml
http://www.vaude.de
I’m not sure if the new Helly Hansen and 66° North jackets have venting options.