SectionHiker.com Backpacking Gear Reviews and FAQs 
Waterproof/breathable rain jackets are coated with a polymer called DWR (Durable Water Repellency) that makes rain bead up and roll off the exterior surface of the jacket. Many, but not all, DWR coatings are based on fluoropolymers that have a fluorine atom at one end that is highly hydrophobic. Water is repelled by the fluorine atoms resulting in beading which makes the water roll off without wetting the jacket’s outer fabric.
Reduce Abrasion
Over time, that DWR coating wears off in areas of high wear and abrasion. If you’re a hiker or backpacker, this includes all of the places where a backpack rubs against a waterproof/breathable jacket: under the shoulder straps, along the back, under the hip belt, and inside the arms if you use trekking poles.
Other high wear areas include the ends of your sleeves, the inside of the neck, and alongside zippers. The DWR coating can also be degraded if it rubs up against other items in your backpack, especially if you frequently stuff your rain jacket loose into your pack.
It follows that you can extend the life of the DWR coating by reducing the time that your rain jacket is in contact with your backpack by wearing other garments, such as a wind shirt, or an insulated hoodie, instead of a rain jacket to protect yourself from the wind or to stay warm. Storing your rain jacket in its pocket if it’s stuffable that way or in a separate stuff sack will also reduce the abrasion that results from stuffing it into your backpack loose.
Reactivate the DWR with Heat
While you can restore the DWR coating on a waterproof/breathable rain jacket with an aftermarket product like Nikwax or Grangers, it will never be as good as the factory DWR coating when the jacket is new. During the manufacturing process, high heat is used to adhere the DWR coating to the jacket’s external fabric and to optimally align the fluorine atoms in the DWR coating to repel water.
You can reproduce this effect in a clothes dryer when you notice that rain is soaking the exterior fabric of your jacket, called wet-out, instead of beading up and bouncing off. The density of the DWR coating won’t be as high as when the jacket was new, but at a minimum, all you have to do is to throw the jacket into a drier to improve the effectiveness of the DWR coating. You can get an even better result if you wash the jacket beforehand with a special performance soap like Nikwax Tech Wash that doesn’t leave any residue like conventional detergent.
Reapply DWR Coating
If washing and drying your rain jacket doesn’t improve the effectiveness of the DWR coating, you can reapply the DWR coating with an aftermarket product like Nikwax TX.Direct Spray-on or Revivex Durable Water Repellent Spray. Some aftermarket DWR coatings, like these two, do not require heat to be activated, but others do. Read and follow the directions. You will usually want to wash the jacket first using a performance soap like the Nikwax Tech Wash described above first, before reapplying the DWR coating because dirt, grime, sweat, etc. can interfere with its uptake.
Spray-on DWR products are preferable to liquids that you pour into a washing machine because you can control where the coating is applied. For example, you don’t want to spray DWR on the inside of a rain jacket because it will repel and trap water vapor in the jacket so it can’t get out.
How often should you reapply the DWR Coating to a waterproof/breathable rain jacket? Arcteryx is one of the few manufacturers that provides clear directions on this front. They recommend reapplying the DWR coating after 10-12 heavy uses of a rain jacket. By heavy, they mean when used for active sports like hiking or backpacking and not for more casual use around town. If you’re a frequent hiker, that may well require several applications per year or more.
Good advice thanks.
I think the shocking thing mentioned in this article is that Arcteryx recommends restoring the DWR on a rain jacket after every 10-12 uses, where a use equals any time you put the jacket on with a backpack. That equates to 4-6 times per year for me and most of my hiker friends. To make the DWR last, you also shouldn’t use the jacket except when it rains! With that kind of overhead, is it any wonder that many hikers and backpackers choose NOT to use waterproof/breathable rain jackets!
THIS. I moved to a Sil Poly rain jacket with pit zips.
OMG! That explains why every one of my “breathable” jackets have failed. I knew it wore out but didn’t realize it was that it happens that quickly. I’v also read that the chemical is toxic to the environment. I’ll stick to my $20 Frog Toggs.
It never occurred to me to put a rain jacket in the dryer, I would have thought the heat could possibly damage the material. Are there certain guidelines regarding this such as using low, medium or high heat, how long to leave it in for, etc? In case it matters, I have a Montbell Versalite.
From Montbell
“To dry your Hardshell place in a dryer on “low” heat, at the end of the drying cycle, you may increase the heat to “warm” and dry for an additional 15 minutes. Do not line-dry or air-dry your Hardshell. DWR finishes are heat activated and if the item is not exposed to “low” and/or “warm” heat for at least 45 minutes, then the DWR finish may not be restored. Heat is critical in bringing the DWR finish back to life. After drying is complete, remove the item at once; do not allow the garment to remain in the dryer, as burns may occur if the item sits on the hot metal of the dryer.”
https://www.montbell.us/customer-service/maintenance/
Wow. I had no idea. Yet another reason I subscribe to your website. Thank you!
For rain jackets from other manufacturers – their websites usually have similar instructions.
I much prefer using a spray on DWR as the wash in ones don’t seem to be effective and often there is a very vague instruction as to how much and how long you wash the garment with the DWR solution for. I have machine washed two seam sealed jackets over the years and found the sealing tape lifted off the garment, this was on the warm wash cycle. Throw outs they became. Be careful washing your jacket. I only do this gently by hand theses days. I would be very careful with a tape sealed jacket in the dryer as well. as too much heat may have the same result and render your favorite jacket useless.
Most of the wash-in DWR treatments end up going down the drain, which really can’t be good if you think about it.
I’m glad people are mentioning that. Some of that stuff also washes off into the ground while the jacket is being worn in the rain, probably a lot of it after a reapplication of DWR. The fluorine compounds (PFOA,PFAS) are very persistent after release in the environment. Not every locality samples and analyzes for those chemicals, but it is found pretty much nationwide, including areas known for there outdoors activities. It certainly doesn’t do any good.
That makes sense. I’ve never used spray on DWR. Is there a particular brand that has worked well for you? I see NikWax and GearAid both make them.
I still have some DWR rain jackets but like others I have moved to a Sil Poly rain jacket with pit zips. I’ve tried every method in this article to renew/restore the DWR coating and none have worked.
I went with the same type of rain jacket. I avoid DWR unless it’s a clearance item.
I’ve used Star Brite waterproofing on items that I have otherwise given up on. It is a solvent based PTEF (known usually as PTFE, which is also sometimes referred to as Teflon). It’s highly flammable until dry, especially the sprayed mist. Also if applied too liberally it will detach tape from taped seams. I have yet to see it harm a PU layer applied to the other side of the fabric. When dry it is slick like silnylon. I have used it on items like a Sierra Designs poncho, a GoLite rain jacket (did not delaminate inner layer), Tyvek groundsheet (made it too slick), a 30 year old tent fly and inner (beaded water like new after application), a map… It works better, lasts longer, than the wash-in stuff in my opinion. I don’t believe it has the permanence of silicone. Relatively low cost, can be purchased by the gallon, I use a hand pump garden sprayer in the backyard when applying.
Silicone is not a coating. It permeates through the entire fabric.
and that brand is? thanks
so why bother with a $200 Montbell, instead of a $20 Froggtogg?
Because the Montbell will last much longer and doesn’t have to be thrown out when it gets ripped to shreds because you walked through some tall grass. I’m not a huge advocate for waterproof/breathable jackets but most people still buy them and this article is to explain how to take care of them so they function as best they can.
I am super glad I read about the shortcomings of DWR (Drenched When Rainy?) here, before my thru hike last summer.
My Lightheart gear jacket worked well, and was lighter and more compact than the expensive DWR jacket I had planned on.
Thanks Phil!!
Perhaps making exterior shells of WPB parkas in a material that holds the DWR much better is an answer.
I would think (guessing here) that a shell with a “rougher” finish would do that better than a shiny shell.