Overview
I needed a new shell and could not find authoritative information anywhere to help me make my choice. I knew from experience that breathability was important to me, so I chose the best candidates I could find, and sent them to the lab for testing. I then took them into the field to see how they performed. This is my report.
Different shells have different specialties. Some are ultralight in weight and pack size, which is ideal for carrying in varied conditions. Wind shells can be more comfortable than rain shells, so there are times for each. Some lightweight shells may not breathe as well as slightly heavier shells (due to differences in membrane or laminate technology), leading to trade-offs. In cooler weather, I may choose a heavier winter shell (about a pound / 450 g) for better pockets, features, comfort, and durability.
This report includes test results, debunks DWR myths, examines rain resistance in wind shells, and presents my experience with some top-performing wind and rain shells. All the shells in this report are made with high MVTR (moisture vapor transmission rate) fabrics. Differences in comfort vary more due to features and fit than to differences in laboratory measurements.
Laboratory Testing
Previous Backpacking Light articles tell us that two components of breathability are moisture vapor transmission rate (MVTR) (the best way to measure moisture movement out of our clothing system), and air permeability rate (APR) which measures how much (or how little) resistance a layer has to air movement (e.g., wind). Few manufacturers list this information, and those that do produce widely varying numbers which make comparisons more frustrating than enlightening. To overcome this, I sent them to a single facility – Stephen Seeber’s independent laboratory in Colorado – to ensure uniformity in evaluation criteria.
As Stephen Seeber recently pointed out, APR often gives us a ballpark idea of MVTR (in garments without membranes), but it doesn’t always correlate. The most interesting wind shell fabrics are the outliers: Those with high MVTR and moderate APR. Furthermore, field testing has more varied results because of other factors such as ventilation features and fit.
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Discussion
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Companion forum thread to: Shell Game: Wind and Rain Jacket Breathability Tests vs. Trail Performance
I sent several top wind and rain shells to the lab to measure breathability and then took them on the trail for real-world testing.
A lot of good information, thanks
Good points about rain jacket should be big so there’s air circulation inside, and front zipper to shed insulation when you start getting warm,…
Too bad there aren’t any neo shell garments available. That’s worked good for me in myog jacket
A complaint about available jackets is they’re too short. If it goes down to about thigh level it provides more protection
Too short and you know where the water goes. I had mine made extra long.
Pass through hand pockets, so I can reach into my hoodie. I can vent without opening the front.
Bill, great article. Thorough, yet concise. I learned a lot.
Any thoughts on the Crest Windshell from Katabatic Gear? I haven’t seen much about this jacket, but it comes from a respected cottage company, and it uses the same fabric (Pertex Quantum Air) as your recommended pick for a summer windshirt (Kor Airshell Hoody) at half the weight.
I have not seen a Crest in person. It appears to be a lighter version of the fabric. No pockets or other features, but very light weight. Dunno about sizing.
Agreed with Jerry and Terran about jacket lengths. I miss the days when parkas were cool.
This is a great article. Thanks for your efforts. This backs up a lot of my own observations. I wish I had the ability to send Stephen Seeger garments to be tested, but that would be a very expensive and time consuming pursuit from New Zealand! Even the availability of many of these garments is limited here. I very much look forward to reading the comments and further test results. Thanks again, Scott
Stephen might appreciate that.
Once upon a time, I seem to recall that Roger Caffin had some sort of pipeline set up to ship from his office to the US BPL offices. As I recall, the purpose was for testing fabrics. Don’t know whether anything like that would be possible again.
Pipeline – that was a very long time ago!
Cheers
Glad you like the Motive. Is the Kor Airshell similar to the Preshell?
Hi, Brett. Yes, you talked me into trying the Motive, and I am glad you did. I do like it.
I expect electrospun membranes like AscentShell (NeoShell, Futurelight, Pertex Shield, etc) to be the next leap forward in 3-Layer WPBs. The main competition is membrane-on-the-outside, like Outdry.
Since I happen to have both, I choose AscentShell in warmer weather and Outdry when serious rain is forecasted. Either works but they are slightly different.
Just a wee note here @Bill Budney – Pertex Shield is NOT the electrospun membrane, that’s Shield AIR – it’s all so confusing….
Cheers, Scott
Yes, thanks for keeping me honest, Scott. I had “Pertex Shield Air” in my head, but it didn’t all make it to my fingers. :)
I suffer that disconnect often Bill! Hope I didn’t sound like a “correcter”?
Keep up the awesome work
It’s all good, Scott. Saves confusion for readers. Thanks.
Anyone know the difference between the Motiv Ascentshell and the Helium Ascentshell other than the Helium is Pertex Shield Air. Then there is the Microgravity Ascentshell.
I don’t have any hard data on them. The Helium AscentShell looks good for warmer weather if you want more features than a Visp.
I was tempted to test one for the article until I found Outdry. My interest in jackets with face fabrics has declined since then. The Motive is slightly more comfortable in warm weather and intermittent rain, but the Outdry remains cozy in cold rain.
There is no one perfect garment — only tradeoffs.
I get a kick out of this guy. Many of his points are true, but his conclusion is silly.
Yes, WPBs are imperfect. As pointed out in the article, expecting a jacket to be comfortable in warm weather is a common mistake — that is time for a more ventilated approach (poncho, umbrella, hat).
OTOH, they are more comfortable than straight waterproof when exercising in weather cool enough to want a jacket. The tech may be pricey and over-promoted, but it isn’t a scam, and it isn’t confirmation bias. It’s science.
WPBs do require a vapor pressure differential in order to function. However, just because it is raining does not mean that the outside air is saturated. Unless you are hiking in a cloud, there often is a differential.
Do WPBs need ventilation? Absolutely. Why? Because weather varies, and ventilation works better than breathable fabrics for some conditions. Your garment will handle a wider range of conditions if it can do both.
It’s a cute video, but hopefully we treat the subject with a little more insight here.
Bill – even if all that is true, they still fail to be waterproof AND breathable as soon as the face fabric wets out. You admit this yourself – that you prefer Outdry to traditional WPB jackets. Watching the whole video, my takeaway was that his conclusion was similar: GoreTex is overhyped. My biggest complaint about Columbia Outdry jackets is that the tailoring often seems “off”.  If they had a well tailored Outdry jacket with big pit zips it would be a winner, at least to me it would. I own one of the older Outdry EX Lightweight jackets. My old Marmot Precip is my casual, “around town” jacket, and despite re-treating it with DWR, it wets out quickly. My Outdry Ex jacket goes in my pack if i’m expecting significant rainfall. I still have a traditional Goretex shell for mountaineering, because that’s what “mountaineering” people are expected to wear when you’re with a guide.
And Steven’s attitude towards WPB jackets isn’t any different from Andy Skurka’s
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I’ve found that some WPB fabric keeps me dry for long periods, as long as it’s cool and I don’t have too much insulation for the temperature and exertion level
Jeff: Over-hyped, yes. Not a scam, not confirmation bias, and there is nothing to “fall for” — only nuance to understand better. Most of the detail in the video is pretty good, actually — it’s just those conclusions that are, themselves, over-hyped and misleading.
I don’t recall Skurka ever discussing membrane-on-the-outside.
I understand your point about fit. I kind of like the baggy fit of my Outdry jacket: it is not unlike Frogg Toggs in that the extra fabric promotes air movement. I wouldn’t want any shell to fit “right”, if “right” means trim and good-looking. That’s probably in the HYOH category.
And, yeah, pit zips! Or, really, more like the torso zips on OR Foray or Timmermade MegaZip. I’m in favor of adding ventilation when it is missing. Most of my rain gear has been altered in some way.
Agreed about DWR wetting out, regardless of re-applying it. I think that’s a red herring promoted by marketers. I ignore DWR performance — none of it works well enough for me to care about it. I just assume it is going to wet out in heavy rain. I don’t bother re-applying it.
Also agreed that membrane-on-the-outside is The Way for serious rain protection. Personally, I’m OK with sacrificing a few points of MVTR in return for that MVTR never being impeded by wet out.
As you say, don’t expect any membrane-with-face-fabric to be waterproof and breathable at the same time — that’s a misunderstanding about how they work, other than the few minutes when DWR is active. Yes, they are over-hyped.
Question: Does the DWR on your Gore-Tex jacket perform any better than your Precip? I’m curious about the Yamatomichi hypothesis.
Jerry: I’m with you about some of the electrospun membranes. They are nice in some conditions, and I agree that wet out’s effects can be managed when it does happen. It isn’t as dire as some people seem to think.
Skurka talked about Shakedry & Outdry here  with lots of references to previous thoughts on traditional WPB.
GoreTex’s marketing slogan is literally, “Guaranteed to Keep You Dry“. Is Steven over-hyping a bit, too? Of course. It’s youtube. He’d competing with the likes of Dan Beckers Outdoors and a bunch of other people. At least he makes an afford to objectively test gear. The average consumer is going to “fall for” the marketing slogan “Guaranteed to Keep You Dry”, because it’s literally on the hang-tags for their products. No sales person is going to come up to a shopper and take the time to explain the nuance and caveats, that “dry” doesn’t include your own sweat if you’re a backpacker on the move while it’s raining, is subject to outside humidity, and so-on.
Adding full length pit zips – I should actually look into how hard it would be to add those to my OutDry jacket. I’ve done some sewing, so it wouldn’t be too much of a stretch for me.
GoreTex – it’s new enough that I haven’t had it out in bad conditions yet. I’m taking an Alpinism 1 class with American Alpine Institute on Mt Maker starting July 20, so maybe that will be the first real test of it. (Though I’d rather we have blue skies for the duration of our guided course.)
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Adding ventilation: The hardest part, for me, is cutting up a perfectly good jacket. :)
I’m tempted to add a pack cover to the back of my Outdry jacket to make a mountain poncho that breathes in heavy rain. I made a Frogg Toggs prototype that almost works… still needs some tuning.
There’s YouTube hype and then there’s marketing hype. After you’ve been around a few years, you sort of learn to ignore it and look for the meat. I find pockets help. I can push the fabric away from my body or create a pumping action for air exchange.
Yes, and there is also just plain wrong. That’s the part I object to. Agreed about looking for the good parts. Pretty sure I acknowledged those above. Dunno why we’re still talking about it. :)
Mesh-backed pockets are great, yes.
For rain gear, I’d like to see forearm vents, or just over-sized sleeves, like a wizard. Like poncho sleeves, but longer — the idea being to keep rain off while allowing air movement underneath. Of course with a cinch to button up when it is cold.
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