Why Does Rain Gear Wet Out?

Wet Out despite eVent and Gore-Tex Shell Layers

Wet Out despite eVent and Gore-Tex Shell Layers

The biggest dirty little secret in the outdoor industry is that rain gear won’t keep you dry. 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.

This happened to me (for the millionth time) in heavy rain over the weekend on a I was co-leading for the Appalachian Mountain Club. We ended up walking out because the rain was so extreme and many of our participants were already soaked to the bone. I was nearing my limit as well because my rain jacket, rain pants, mid-layers and base layers had wetted out, and the pace of the group was slow enough that I couldn’t generate enough body heat by walking fast to stay ahead of the chill (see Why You Should Hike in the Rain.)

What is Wet Out?

Wet Out occurs when your rain gear stops venting perspiration because the humidity outside your jacket is higher than on the inside. During sustained rain or drizzle, your perspiration accumulates on the inside side of the your rain garments and will gradually soak your inner layers.  It doesn’t matter if your rain gear is made out of Gore-tex, eVent, Tyvek, Nylon or some other breathable membrane, all rain gear will wet out, sooner or later.

What about DWR Coatings?

Most 2-3 layer breathable rain jackets and pants are coated with a Durable Water Repellent (DWR) finish that makes water bead up and roll off them without saturating the exterior fabric. The breathable layer is often sandwiched under or between two fabrics which protect it or provide a secondary surface that moisture can evaporate from. When the DWR coating wears off, the external fabric can become saturated and prevent the internal membrane from passing water vapor, even if it is not raining anymore, because the humidity on the outside of the middle layer is still at 100%.

This is a good reason to keep 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 perspiration accumulation inside the breathable layer will wet out your garments when it is raining outside.

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 conditions. 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 you 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.

Additional Resources

How to Buy a Hiking Rain Jacket

Mechanical Venting, Pit Zips, and Layering

 

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34 Responses to Why Does Rain Gear Wet Out?

  1. Robin June 6, 2012 at 2:40 am #

    Absolutely right, Philip, no wonder fabric will keep you perfectly dry. If it’s not too windy, an umbrella is a huge help. It means you don’t have to use a hood, great for temperature regulation and releasing sweat. You can even get away with just using water repellant windproof. In most circumstances, I now carry one.

  2. Basti June 6, 2012 at 3:02 am #

    That’s exactly why I rate the design of a jacket (pitzips, long zippers and other options for venting) higher than the used fabric. As long as one is able to move the water saturated air outside using a venting option, the only issue to have with the fabric is that it’s durable enough not to fall apart!

  3. dave June 6, 2012 at 3:46 am #

    The answer is wool. Woolrich, Pendleton or Filson and a good synthetic wicking base layer. Working as a surveyor in the Pacific NW taught me this. Sometimes it takes two Alaska shirts but this system is twice as breathable as Goretex which incidently shreds in the Marion berries. Midwest thundershowers you might as well pitch a shelter and wait it out but when the cold rain sets in wool is best. It is not however, ultralight. It is warm while wet. Above 70 degrees F getting wet most likely will not kill you. 33 degrees you better have wool or polargard or holofill. Fleece is comfy till it is soaked.

    • Steve June 6, 2012 at 6:59 am #

      What Dave said. Wool wool wool. I’ve gotten soaked out before, but my Ice Breaker base and mid layers kept me warm even when at a slower pace.

      That said, don’t do this on a through-hike, cause you’ll have to wait to dry out.

      • Fabian Kall June 18, 2012 at 1:20 am #

        Right on!

    • Ross Gilmore June 6, 2012 at 8:18 am #

      That has not been my experience with my wool clothing. Whenever I have gotten wet, I’ve gotten cold.

      • P. Beauchamps September 11, 2012 at 8:50 am #

        Ross — Check your “wool” clothing for other fibers. If it’s 15% nylon, that’s okay, but be sure there’s NO cotton in it. Cotton is like a sponge — it gets wet and won’t be dry again without long heating. You can freeze to death in cotton. You can be better off naked.

        Anyway, wool does insulate when wet, but it should be obvious that it doesn’t insulate as well as when it’s dry. You may have to wear multiple layers of wool, or have a windbreaker over the wool, or other tricks. Wool “keeps you warm when wet” COMPARED to cotton and other such fibers.

        In all cases, the “warm” comes from you. If you sit around in soggy wool, you’ll get cold. Get active — walk — and you’ll warm up if you’ve got anywhere near sufficient insulation.

        BTW, it’s my experience that getting cold and wet makes me depressed. This might just be S.A.D. (which affects me) in another guise. So I TEND to just sit around under such conditions. Not good. Ya gotta get moving!

  4. Marco June 6, 2012 at 7:22 am #

    Philip,
    “The breathable layer is often sandwiched under or between two non-breathable fabrics which protect it or provide a secondary surface that moisture can evaporate from.”
    I think yo made a slight error there, but I understand the meaning. two layers of NON-BREATHABLE fabrics???? All the layers need to breath, else it is like putting on a sheet of plastic. I think you mean non-waterproof. Breathability is how the WPB’s work.

    Wet out occurs from the outside as well as the inside with WPB clothing. This is not changing the normal operation of the WPB layer. WPB’s generally move humidity from high concentration to low concentration. Not a violation of physics, of course, it will maintain your bodies wetness at or about normal when you use it. (It does slow venting *out* of perspiration a lot, hence feels a bit warm.) When the weather side gets wet, it still moves from high concentration to low. The inside (you) happens to usually be lower than the outside so it will allow water to penetrate.

    The second thing that happens is that the outside protection layer (mostly against dirt and oils) will wet out, even with a good DWR. This will prevent operation of the WPB because there is no longer any breathing space. Moisture will typically act like a non-breathable film (surface tension) over the WPB layer…turning off any venting in that area. If it cannot breath, it doesn’t work. Think of an old canvas tent, works fine till you touch it, breaking the srface film.

    In escence, this means that in short rain showes, it works very well. In longer showers, it fails because the DWR fails and you could wet out quicker. Any DWR coating needs to be maintained over the WPB to stop *filming* and *water take-up* by the WPB material. As you say, it is very important to keep this layer well maintained and seperated from actual water. I agree 100% that this is the key to WPB fabrics. I am amazed at the number of people that do not understand this. DWR and WPB layers work together. The inside layer often gets dirty from body oils, also making the WPB layer fail. While less important than the outer layer, it is necessary to launder the jacket periodically, and, restore the DWR. Usually once per week or less if you wear it a lot.

    A simple vinal jacket works almost as well, except, it allows NO breathing. You eventually wet out from the inside. A pancho works best since it is open and allows a lot of ventilation (yes, it flaps around a lot and *can* trip you up.

    • Earlylite June 6, 2012 at 8:56 am #

      Good catch marco – you understood my intent. Removed the word. It is amazingly difficult to explain this in laymans terms.

  5. Rob June 6, 2012 at 9:50 am #

    I haven’t wet out in a while (yeah frog toggs!), but that’s been more matter of luck than the inherent excellence of the gear.

    I carry a spare pack liner – mostly for use in clothes washing and as an extra containment bag. In a hypothermia situation, cutting neck and arm holes in it, gives you an extra vapor barrier and warm up clothing. (I’ve used this more often with young scouts than myself).

  6. Scubahhh June 6, 2012 at 7:01 pm #

    A big part of the problem is overdressing, which gets you sweating big-time in the first place. Say you’re cruising along comfortably in your U60 tshirt and Zephyr zip t-neck. It starts to rain, so you put on your jacket, which is another layer of insulation and makes you too warm, so you start to sweat (more) and ultimately get too cold. Makes more sense to lose the Zhyr or the t-shirt when you put on the jacket doesn’t it? Works for me… Sort of!

    • Timrules June 10, 2012 at 11:37 pm #

      I live in a proper rainforest (North Vancouver, BC, Canada) and this has definitely been my experience.

      Your body is sweating in an attempt to cool itself – if your body is trying too cool itself in the rain, either the temperature is very warm or you are overdressed.

      Wetting-out is inevitable at times (b/c your body is ‘trained’ to sweat when it starts working, ‘expecting’ to need to cool), but this can be greatly reduced by wearing less … I think of my shell as a thick sweater, knowing that I won’t get the venting/cooling that I would get if it were dry … I always take a touque (and often a down sweater even in relatively mild temperatures), but I save them for when I’ve stopped moving & sweating – makes a huge difference.

      When I’m really working (trail running, skiing, snow shoeing or carrying a pack in rough terrain, that kind of stuff) a technical T-shirt and shell is good to about +5C … long sleeve + shell is good to probably -5C, as long as you have the warm stuff for when you stop … above about +15C just accept you’ll get wet on the move and save your fancy rain gear and a dry set of clothes for camp: when it’s that ‘warm’ your body is going to get wet (either through sweat or rain) – why get all your clothes wet as well?

      Otherwise, it becomes a bit of a mug’s game: every time you stop, you add clothes to stay warm, but then you sweat them up and they end up cooling you as soon as you stop, so you add more clothes to get warm, sweat them up, and so on …

      Half the idea of “layering” is to trap insulating air between the layers, but the other half is to be able to take off the layers to regulate your temperature according to the environment and what your body is doing … take the layer off BEFORE you soak it in sweat!

      Finally, when in doubt – merino wool (Smartwool, or whatever).

  7. Tom Murphy June 6, 2012 at 9:25 pm #

    When then temps are lower than say 70 F, I hike even slower when I put the rain gear on in an attempt to prevent from overheating.

    When it is warm out I don’t put the rain gear on. Just make sure I have dry clothing for camp.

  8. Pam June 6, 2012 at 9:58 pm #

    Hiking in a rain jacket (at least in the Whites) seems like a choice between getting wet from the inside (I sweat a lot) — or the outside (as in not wearing a jacket at all). I haven’t used a poncho hiking (sometimes I use my jacket like one though) or figured out how to use an umbrella and use poles at the same time. Speaking of, it would be great to see a post devoted to trekking umbrellas — what kind to use, can you attach to pack etc.

  9. Earlylite June 7, 2012 at 8:58 am #

    Hey Pam – I’m not an umbrella kind of guy. But if someone wants to write a guest post….

  10. David June 7, 2012 at 4:45 pm #

    How do you feel about the Poncho?

    Breathable to avoid interior humidity – while some moisture may leak in its not a “downpour” and generally weighing in around 10 oz for a technical Sil Poncho brings down your total “raingear” weight (Jacket, Pants, Waterproof Shoes, Pack Cover) by several pounds.

    Works great for me – especially during more grueling hiking trips.

    • Earlylite June 7, 2012 at 4:49 pm #

      Bad memories from my childhood. I also like pockets, lots of chest pockets. Never say never, though.

  11. john pasmore June 7, 2012 at 10:12 pm #

    I’ve tried to find gear that works across sports hiking/sailing or even kayaking but it’s tough.

    Sitting on watch sailing in a driving, north east november rain in a Marmot Gore Tex Jacket was not fun. It wet out. And with spray off bow you get a salty covering that totally negates “breathing” – scrapped breathable for sailing and don’t get why they even attempt to make these.

    That said, like the poncho option, nylon, like brands like Pearl Izumi that makes running/cycling gear out of polyester that has good venting. Totally agree with wool as the other issue about fleece and sailing/kayaking is that it will absorb LOTS of water and would be dangerously heavy in the unfortunate event of falling out/off boat.

  12. Chas Fisher June 8, 2012 at 4:47 pm #

    Full and up-front disclosure: I am employed by Nikwax, which makes products for re-waterproofing “waterproof-breathable” (W/B) materials.

    Nice post! In the waterproofing business, we typically use the term “wetting out” to refer to the condition when the outer face material of a W/B laminate becomes saturated with water, thereby rendering the “breathable” function of the technical fabric inoperable.

    Technical W/B laminates work very well under ideal conditions, but it’s vital that the outer material repel moisture, or you might as well be wearing a plastic garbage bag!

    So my professional and personal advice would be to take care of your gear:
    1) Clean when dirty, or when the face fabric obviously wets out. Sometimes all it takes to renew the DWR is to clean the garment/footwear with a non-detergent technical cleaner!
    2) If the garment/footwear still wets out easily after a good clean, revitalize the waterproofing with a product such as our Nikwax waterproofers (of course there are other brands too)
    3) When not using your gear, make sure it’s clean and dry and stored properly to avoid mildew and/or bacteria build-up.

    thanks, and stay dry!

    Chas Fisher
    President, Nikwax North America

  13. Jeff June 9, 2012 at 4:06 pm #

    If the weather is reasionably warm, 60+, why not just use a pancho and shorts if you are going to get wet anyway.

  14. lostalot June 11, 2012 at 4:24 pm #

    60F is far from reasonably warm for a wet person and the rain is typically a lot colder; add some wind….

  15. Illimani94 June 24, 2012 at 11:03 pm #

    My experience

    Keeping shell gear clean and refreshing the DWR are both really important for helping the waterproof/breathable gear waterproof AND breathing. Learned that one the hard way.

    I used to think WHICH waterproof/breathable didn’t matter that much, but

    For staying dry from the inside, appropriate layering and pacing are the key. Last autumn trip to the Cascades we had rain and wet snow, temps in the 30s and 40s. I hiked most of the time in a long-sleeve Capilene 1 shirt, a short-sleeve Cap 2 shirt over that, the shell, and a baseball hat. Once I did have to hide in the shell the pace slowed down so that I wasn’t making more heat than I could dump via the partly unzipped front and the pit zips. When we reached camp i ducked under a tree to add a Driclime windshirt under the shell, a fuzzy hat, and eventually the Primaloft sweater as well. The same layering scheme served me well through our hike of the Wonderland Trail.

    If you’re in a place where it’s going to rain long and often, one really helpful shell layer is a lightweight tarp. If it’s relatively easy to set up you can arrange someplace dry to change layers or take a rest break. The “bothy bag” appears to be an easier-to-use, but less versatile, take on the same concept. The important thing is to have some type of shelter where you can adjust layers without getting everything wet, or take a break without risking hypothermia.

    I’m not a wool fan, but then I get the itchies from it pretty easily. I stick to the synthetics if I want to remain comfortable. In the days when I did wear a wool shirt, I found if it got wet it was not that warm, and a lot harder to dry than a fleece sweater. Wool is definitely sturdier than any synthetic fabric I’ve used.

    Ponchos. I’ve used one, with rain chaps to keep my legs dry if things got windy. Too much flapping for me, but I did stay fairly dry and had few condensation problems. Plus you can change layers inside a poncho, which is more than I can say for my shell jackets.

  16. Scott July 9, 2012 at 11:31 am #

    A quick solution to the safety issue in this case is to put a vapour barrier next to your skin, say a garbage bag with holes for head and arms, then a dry layer from your pack, then another vapour barrier, say a 100% water proof shell. As long as the dry layer is a good insulator and stays dry, then hypothermia (and hence safety) should not be an issue. The key is keeping the insulating layer dry, not keeping you dry (even though the original objective at the start of the hike was to keep yourself dry!)

    You might be wet on your skin. You might even chafe. But you will be warm.

    • Hillwalker October 30, 2012 at 3:42 pm #

      Hey Scott:

      I’ve always been intrigued by vapor barrier stuff.

      I know this, I put those grocery store bags over my feet, feet into socks, another layer
      of grocery bag over the sock, bag into shoes. Shoes get wet, my feet get ‘damp’ and the sock stay dry. Not ideal, but when i pull my wet shoes off, I’ve no trouble keeping my feet warm.

      I own a fair amount of Stephenson’s Warmlite gear. I use it only when things are really really cold. I trust it implicitly.

      here’s what they have to say on the subject of vapor barrier stuff:

      http://warmlite.com/vapor-barrier

      And for the record, they consider all this talk about ‘breathable waterproof’ and such to be a lot of marlarky, marketing hyperbole.
      I’m not sure they’re wrong.

  17. Hillwalker October 30, 2012 at 3:31 pm #

    Good day all:
    Some intelligent stuff here, and I was hoping to actually learn something I didn’t already know, and I guess I have, but I still remain confused.

    I live in the mid-atlantic region of the US, and the weather here is pretty mild to moderate,and the part I have the most trouble with, like many of us, is that weather in the 50s to mid 30, very high to fully saturated humidity, and drizzle to downpour rain.

    If I wear stuff you can’t walk in, like industrial construction grade foul weather gear, I can stay warm. If I wear ‘lightweight backpacking’ rain gear, I can’t. Not for long anyway. eventually the outer skin of whatever the garment will become soaking wet, waterlogged, what I suppose you are calling ‘wet out’ and that starts stealing my heat, and I go heat negative. When I get to shelter, I can peel off a bit, find that I’m mostly dry, just really cold.

    Let me give an example.
    I’ve got this fancy patagonia thing, has those nifty ‘waterproof’ zips. It has an external pocket with a waterproof zip. I can put my cellphone in there. Hop on my bicycle in a downpour, ride into town, about 5 miles away, get cold in 40 degree driving rain, arrive, strip out of the jacket, which is now totally soaked. I’m mostly dry, but cold, and I take my cellphone out of that external pocket (which is separated from me, double layer, the pocket is external remember) and the cellphone is wet. No, it’s not my sweat, it’s not condensation. If it were condensation, then when I put the same cellphone in a ziplock, then it would still get wet, but it doesn’t. The ‘breathable waterproof’ fabric, once soaked, is just that, it’s soaked. Water comes through, yes it does.
    I like the garment, and I’m considering treating the front of it, and across the shoulders with thinned down silicone to actually waterproof this ‘breathable’ fabric.
    I’ve owned a lot of goretex stuff since I first saw it on the market in the mid-70s, and in the snow, it’s fantastic, I love it. But for that low temp wet cold, , man, I’ve just never had any luck at all. I’m told, like everyone is told, that I can re-invigorate the dwr layer by low temp ironing, or tumble drying at a low temp. But this jacket, I’ve had for a year, I’ve used it less than a dozen times, and I treat it with the utmost care and I’m just not satisfied, and I’ve never been satisfied with any ‘breathable’ lightweight stuff in these low temp, rainy conditions. Old school waterproof stuff seems to work okay.

    Clarlification,
    External pocket, is a second layer of the same shell fabric laminated on the shell, with a waterproof zip. The side of the cellphone facing the exterior of the shell is the side that gets wet. If it’s in a bag, the side of the bag facing the exterior gets wet, the phone doesn’t. Condensation? really? if so, then why doesn’t it condense on the side facing me?
    Because the side facing me is at a temp above the dew point, due to body heat, so the outside is below the dew point, so any moisture condenses out. okay, I get that, so why doesn’t that same action occur in an external pocket of a grundens foul weather parka?
    Note: The grundens foul weather parka can be toweled dry, because the fabric absorbs little to no water, because it’s not ‘breathable waterproof’. The breathable cannot be toweled off, because it’s *not* waterproof, but absorbs water. IM-well considered-o (and experience).

    • Daydé October 30, 2012 at 4:29 pm #

      just a thought, but perhaps the water vapor from your breath while riding on the bike puts a high amount of water vapor heading back into your jacket. just a thought but seems plausible as you are breathing harder while biking and the vapor of your breath is blowing in the wind directly back into your jacket/chest pocket (I think you were trying to imply the water vapor should be coming from your chest outward but this would be inward accounting for the vapor on your phone. not a scientist, just a super smart guy :P but really i think in the situation you are describing you dont need lightweight gear and might as well go with something fully waterproof/not breathable and expect to get a little sweaty on the inside (just like you do on warm days in the spring). if you are really concerned with staying dry with lightweight gear, you are unfortunately required by the current offerings in the lightweight WP (perhaps not with Polartec’s new offering), to understand more about your “patagonia thingys” individual best practices, as well as what keeps you personally warm and comfy from the wool/fleece/synthetic layer combos available for under your shell… and both of those things require you to use your garment repeatedly, without it working, until one day you just seem to be able to stay warm and dry through *nearly* all storms. if you are outside all day with lightweight WPs, and its raining, you should expect to get wet though

      • Hillwalker October 30, 2012 at 7:28 pm #

        Hey Dayde`

        It’s a thought, it’s an interesting thought.

        I think Scott’s concept above might bear on this as well, I might experiment
        with VB, and see i get similar results, if i do, I’ll know it’s the garment.
        It’s not so much as staying dry, as staying warm. And not even comfortable,
        but not going heat negative. I’m okay with cold, and I’m okay with wet, I’m
        just not okay with miserable. :)

        fwiw, I just did the same ride, just now. in the rain, 92% relative humidity, 36 degrees, and light rain, using a trashbag VB, and I was much warmer, if not
        too warm, and the inside of my jacket was still lightly damp, but nowhere near as ‘wet’. So, maybe condensation after all my protestations to the contrary. would still be nice to just shake most of the water off the garment when coming inside.

        Thanks for the input.

        • Earlylite October 30, 2012 at 7:40 pm #

          I’m glad you both has this conversation today. I went and bought some VB socks and gloves from Warmlite. Incidentally, I also spent the day wearing a pair of vapor barrier socks in my new mountaineering boots. My feet were dry when I took them off despite being too warm all day.

          • Daydé October 30, 2012 at 9:15 pm #

            i very much like the poncho for the venting + WP and have used it well in a variety of situations. I wear the poncho over the backpack in light wind so as not have to deal with the heavy pack or wear it under the pack in strong wind to secure it down a bit more and keep it from blowing all over, as I also line my pack w/ a trash bag in order to keep my down garments warm and dry for camp in the event of strong wind.. paired with a fleece (r1) or a more breathable softshell w/ DWR under the poncho and mountain hardware outdry (epic) gloves, i stay dry enough to not be “miserable” as I completely agree is the improper way to be in the mountains. id like to start incorporating VBL socks for rain/frosty mornings over breathable shoes but havent yet – the warmlite seem like a good option tho. id also like to look into the chaps to compliment the poncho that a few lightweight companies offer to address leg warm but dont generally feel it necessary when I’m hiking to keep my legs warm until full on snow season requires the hardshell bibs and snow boots.

  18. jeremy martin December 9, 2012 at 6:32 am #

    well my response is you dont know i live the west coast been here 45 years now…well my age too but grew up on the waves of long beach tofino bc im a faller on west coast and of yet i have never or yet have the best raingear in town you will always get soaked trick is wear base clothing and some light to medium wool clothing have a plan and pack spare clothes… and pack light i stilll get soakead to the ass in extreme rain well live it love it until those clothing manufactures can come up with something ill try it on till then here is too the rain jeremy martin skull lake falling west coast bc port alberni bc

  19. Bezmozgliy Baran January 10, 2013 at 1:51 pm #

    Yes, even 30 min bicycle ride to school makes my “waterproof” wear wet out. I figured that the garment must have as many vents as possible to simulate an umbrella: rain does not penetrate, but body gets all the wind it can get (to carry away the moisture). So, I set out to modify my rain gear. Currently it only has vents on the back. I will get plastic vents which are holes with little cap-visor (or sphere visors) over them. They are either glued or stitched over the holes made in the garment. I read the vents must be under arm pits, but I will also make them everywhere on top of the sleeves, shoulders, etc, so to create a chimney effect: hot and moist air will be drawn out to the top through them. So far I am searching for those vents. I got two, from some very undersized trashed clothing and that’s where I got the idea.

    • Bezmozgliy Baran January 10, 2013 at 1:54 pm #

      Oh, I just saw other options: poncho, etc. I will try anything to keep me away from rain and prevent wetting out the clothes.

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