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Why do Waterproof/Breathable Rain Jackets Wet Out?

Why do waterproof breathable rain jackets wet out?

The biggest dirty little secret in the outdoor industry is that waterproof/breathable rain jackets won’t keep you dry and will wet out. It doesn’t matter if you buy a high-end $450 Arcteryx Gore-tex Parka or wear your bathrobe, they’ll both Wet Out in continuous rain and leave you soaking wet.

What is Wet Out?

Most 2-layer or 3 -layer waterproof/breathable rain jackets and pants are coated with a Durable Water Repellent (DWR) finish that makes water bead up and roll off without saturating the exterior fabric. The breathable layer is often sandwiched under or between two fabrics that protect it or provide a second surface that moisture can evaporate from. Wet Out occurs when the external DWR coating wears off, the jacket’s outer fabric becomes saturated and prevents the internal membrane from passing out water vapor.

This is a good reason to maintain your DWR layer regularly by washing your rain garments and reapplying a DWR conditioner like Nikwax TX-Direct Spray-on Water Repellent Treatment to restore it, but it doesn’t change the fact that the DWR coating will rub off quickly, particularly on your shoulders where your backpack shoulder straps rub it off. It’s less of an issue for runners and downhill skiers because they don’t wear backpacks like hikers.

Wet Out Mitigation Strategies

If your rain gear starts to wet out, you run the risk of getting chilled or even hypothermic in cooler weather. Here are a couple of things you can do to mitigate this risk and still keep hiking.

  1. Hike faster, keep eating and drinking to keep your core temperature up. Dehydration can accelerate the onset of hypothermia, so keep drinking even if you don’t feel thirsty.
  2. Put on additional base and mid-layers. While these may eventually become saturated, additional layers will help you retain more body heat. They will also disrupt the transfer of cold from the surface of your jacket or pants to your skin. Your layering system should work to keep the layer against your skin dry and move moisture away from your skin.
  3. If you have pit zips on your jacket, open them to help vent moisture. Pit zips are underrated in this era of breathable, waterproof garments.
  4. If you can’t stay warm, set up a shelter and get into your sleeping bag to warm up. It will stop raining eventually.

See Also

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39 comments

  1. After reading your LightHeart jacket review I decided to go that route and have never been happier. Thinking Frogg Togg rain jackets are the same thing except without pit zips, which is probably why they are less expensive than LightHeart. DWR coatings are great new or even refreshed but disappoint eventually. I can see the case for protection and features, and have a few higher end jackets, but seem to reach for the old fashipn silpoly the most.

  2. How do you prevent the rain from coming in the open pit zips?

  3. Great article Phil… been a long time stalker of your page. But haven’t commented in forever. The group I backpack with have a joke that you can only ever get so wet. It just happens to be, whenever I go out on a trip. Great point about looking out for hypothermia. We’ve been out and run across people that aren’t as prepared for that eventual full saturation that will happen, regardless of the $1000 dollar gear or a trash bag with a hole cut in it.

  4. I wear a Simms Guide rain jacket when fishing on a drift boat for 10 straight hours of rain and I have always remained completely dry.

    • But you’re not hiking. Standing still on a drift boat doesn’t really exercise the breathable quality of a 3Layer rain jacket or result in the same level of abrasion that wearing a backpack over a rain jacket incurs. Anybody can stand around in a $450 gore-tex jacket and stay dry.
      https://www.backcountry.com/simms-guide-classic-jacket-mens
      Neat jacket though. Love those chest pockets.

      • No.
        Got hypothermic in a drift boat this year when my marmot wet through. Standing still in rain and plunging conditions is worse because you are not generating body heat. Upgraded to gortex guidewear. Big difference.
        I was okay unil the base layers soaked through. That is even wearing a paddle veat.

  5. I am glad to see that I am not the only one advocating for the use of bathrobes in the outdoors.

    • What i love about a poncho is that they can double as a dining/ reading fly, esp in the northwest…add an umbrella and moving around camp, even in ho rainforest is easy…decades of Pacific northwest hiking, climbing, backpacking, nothing has kept me more reliably dry than a simple, knee length poncho

  6. Do you have any thoughts about the fabrics with the polyurethane layer on the outside like Columbia Outdry? Seems to me that they don’t wet out and may retain some of their breathability during sustained rain.

    I also think that wetting out dramatically contributes to body cooling due to the evaporative cooling effect. All the water that is absorbed by the outer fabric has to dry out at some point and when it is windy will cool you down very quickly. The Outdry fabric doesn’t suffer from this nearly as much.

    The only downside I see to the Outdry is that the waterproof layer is more susceptible to abrasion.

    Beware, I am biased because I use several different Columbia Outdry raincoats and really like them.

    • Columbia has sharply curtained the availability of Outdry jackets. The problem with Outdry from a hiking perspective is that it’s very thick and very hot, so you perspire much more when you wear it hiking. I’ve also found the hoods of Outdry Jackets to be plain awful. I suspect they’re all sized for ski helmets instead of humans.

      You can prevent wetting out from chilling you with a regular waterproof/breathable jacket by wearing a fleece or wool midlayer. You really only get super chilled if your skin is wet because water conducts cold about 25 times more efficiently than air. A midlayer, as long as it stays reasonably dry on the skin facing side, prevents that.

      • I like my Columbia Outdry, but I use it as a cool weather spring/fall jacket. It’s much too heavy for summer. It would be much improved if it had pit zips.

        For summer, I use either a Frogg Toggs poncho (not the jacket) or Marmot WP/B with pit zips.

        I’d rather spend money on several different inexpensive jackets for a range of conditions instead of one $400 jacket.

  7. Good points about how quickly the DWR can wear off. Between wearing a backpack, wading through wet underbrush, getting sweaty and dirty, I need a jacket that will stay waterproof through all that abuse – I don’t want to have to remember to add DWR treatment between trips.

    I’ve only tried a couple used high-tech wpb jackets and wasn’t impressed, but it’s probably because the DWR was gone. I’ve been impressed with some cycling jackets and a Columbia light winter jacket (don’t recall the name) I bought my daughter that don’t have “crinkly” water permeable layer but instead, I don’t know, feel more like neoprene – they seem to bead water forever no matter how much abuse they get, but are more like a rain-worthy insulating layer (and pretty heavy/bulky in your pack) rather than anything I’d want to wear/carry in summer.

    For summer and shoulder seasons, I prefer an XL Frogg Toggs – covers my pack, ventilates a bit from the bottom, and surprisingly I’ve never ripped on underbrush/branches.

  8. This is why I prefer to hike with an umbrella. I can’t get wet if the rain doesn’t touch me.

    • Kris Whistling Treason

      Where do you hike ? In the UK the rain is frequently sideways.

      • In open terrain, you can tilt the umbrella so that the shaft is parallel to the direction of the rain. In windy conditions, that may be nearly horizontal.

        Umbrellas don’t work well in dense woods or bushwhacking through overgrown areas, though.

  9. I don’t think the outer layer has to become saturated. In a good torrent, a layer of water will flow over the jacket blocking any breathability. Internal water vapour will have nowhere to go, and cause inner layers to wet with body vapour. I suppose with a waterproof breathable fabric, it may evaporate if the weather improves, but I doubt it will dry right up inside without removing the jacket.

  10. DWR = PFAS/PFOS.
    These chemicals are really, really bad.
    Reason enough to avoid current formulations of DWR.

    • Fjallraven doesn’t use a forever chemicals. The wax (extra) rubbed on helps with the wet. the price is off putting. Its a bit of work but worth the slight inconvenience.

      • Not for me. I view the wax as an unpredictable pain in the ass. I’d rather wear something permanently waterproof when I need moisture protection. That way I always know it will “work.”

  11. For years and years, I have been plagued with wet-out; but the cure is simple and cheap. A cape! I have used an old fertilizer sack cut open to give a hood and shoulder cover which to a large extent worked. A tent footprint as a cover-all cape and that though ungainly worked well. Now I have a tape-seamed sil nylon commercially made backpacking cape which doubles as my ground cloth and a pack cover. Now I stay dry and comfortable ……Great!

  12. When I first started backpacking in my youth all I could afford was an Army poncho. When I could afford it I purchased Goretex jackets and always experienced the inevitable wet out no matter how much I treated it with DWR products. As the years passed I tried a poncho again and realized for me that’s
    the way to go. Protects me and my pack. Only downside is in strong winds it can be a bit unruly.

    • Hi Mitch, a length of bailing twine if to be found, a bungy or a designated belt or tie around the waist controls the wind or better still loops inside the poncho/cape that your hand can hold is best. (See large cycle capes)

  13. Ray Jardine, more or less the originator of the light weight backpacking movement, made the same observations in his early books about his experiences on the Pacific Crest Trail, back in the early 90’s, with a bit more focus on the fact that sweat will soak you from the inside, and that’s on top of Wet Out. Maybe his major insight was using a trail umbrella in all “drizzle” conditions, and when that didn’t work, go to full waterproof plastic materials, and wear a little as possible under the plastic. Very lightweight umbrellas are now available. I used one to do the TMB in France, rained nearly every day, worked great, and its an EDC item in my summer day pack in the mountains.

  14. OR AscentShell (Pertex air-permeable membrane) is super abraaion-resistant and breathable. I’m never going back to Gore-Tex, I’d rather wear a contractor bag and save $497. Wore my AscentShell from 13k feet to the summit on Rainier and did not overheat. Then got caught in a snowstorm on the way down (started nuking at the summit) and it did not wet out. Great shell. I would not be wearing a LightHeart jacket high up on a real mountain, that’s for dang sure.

    • I’d wouldn’t recommend a lightheart jacket except for lower elevation hikes. When I go high, I also wear a heavier and thicker and much more technical waterproof/breathable jacket like an OR Foray or a 3L Goretex I have. They work a lot better in cold weather when there’s a bigger temperature gradient between the inside and outside of your jacket. But i also only buy ones with torso zips or poit zps at a minimum to dump extra body heat so I don’t perspire.

      • To my surprise (since I run hot), the OR Helium Ascentshell doesn’t have pit zips yet follows through on the marketing hype that it breathes so well it doesn’t need them. Air-permeable fabrics are where it’s at for me. LightHeart is a nice easy hike emergency jacket to have though :)

  15. Mark’s comments – “DWR = PFAS/PFOS. These chemicals are really, really bad. Reason enough to avoid current formulations of DWR.” have put into print my concerns which have left me not recoating my rain wear, not buying new rain wear and being ok with getting wet. Do you have anymore info on rain gear that does NOT use the forever chemicals ruining our water & possibly our back country?

  16. Hi Philip. Very interested in your article and trying to understand what I can expect from my Berghaus storm cloud jacket. I have cleaned and re proofed using a wash in DWR product. I was pleased with the initial beading but after 30 mins the jacket had wetted out.

  17. Hi Philip. Thanks for the reply. Sorry but I am a little confused. The article suggests even the best jacket will wet out but also that wet out occurs when the DWR coating wears off. Do you have any stats as to how long a jacket should withstand constant rain for? Ie in my case the re proofed jacket can only stand 20 mins. So what is the benefit of re proofing if the the jacket only beads for 20 mins?

  18. Hi . Can anyone please help me out on this with some advice. I feel as if the industry has taken me for a ride. Jackets that don’t keep you dry and re proofing products that appear to be useless. This article states that wetout occurs when the DWR coating wears off. Ok that makes sense. So when you re proof how long can the jacket repell the rain before it wets out? My case around 20mins in light rain. Re proofing is not cheap so what is the point if it can only give you 20 mins. Or is that just supposed to be enough time for you to run back home or find some cover. Neither of those are the reasons why i have spent the money I have. I want to enjoy the great outdoors come rain or shine. Thanks Mark

  19. Brilliant to read this, Philip! I work in building science, and the same dirty secret is at action in many of the dumb things we currently do in construction and repair.
    It’s all basic physics in action, but alas today the principles at play are but little understood in our tech-obsessed societies, where we think the solutions always lie in the future rather than the past…
    The reason woollen ponchos (and jumpers, and best of all greatcoats and tweed jackets) work so well is the same reason ‘traditional’ buildings made of porous materials keep the rain out: raindrops are held in the surface pores, and the air they are trapping in the deeper pores prevents the water penetrating further. The only way for a raindrop to get in is for it to hit a water-filled capillary opening out onto the surface, and that is vanishingly rare unless the materials is already wet (for a coat, say by soaking it in a bucket – and that will take some time! Or for a building by a plumbing or gutter leak or something like that). So for the most part the raindrops are held on the surface and then evaporate before they can do much harm.
    By contrast, the modern obsession for clothes and buildings is with ‘waterproofing’; which means trying to keep the water out by using largely impermeable surfaces like plastic (or for buildings glass and metal and cement). These don’t have pores that hold the water, but instead they allow it to bead, collect and then run down under gravity. Then, when the flowing water hits a joint or a seam, capillary action will wick it through like a siphon.
    The other important aspect of the physics is that, despite what manufacturers maintain, vapour cannot travel through porous materials (and that includes goretex): it can only travel effectively through a permeable material as a liquid. Materials like membranes actually function – for a while – by exploiting exactly that process: their odd pore structure seems to encourage condensation of vapour in a way that quickly creates a few liquid flow paths from the outside to the inside, and these allow some liquid moisture to travel through – at first mostly sweat, travelling outwards. But after a while, if there’s a lot of moisture about, you just get too many water-filled capillaries, and the system fails. (It’s also why vapour transfer tests give such odd results, by the way.)
    … so that’s (some of) the science behind why Icelandic farmers and North Sea fisherman have always loved their knitted jerseys, and old building surveyors their tweed jackets! Eee by gum, they weren’t stupid in the past…

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