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DWR, dirt, oil, and why you care about them

having spent most of a very rainy sunday outside, it occurred to me that it would be worth discussing this.

DWR stand for 'durable water repellent.'  most nylon shells available today have some kind DWR coating that helps make the fabric more resistant to water.  all clothing with a waterproof/breathable membrane has the coating.  in practical terms, a jacket with functioning DWR will, at least for some period of time, have rain or water bead up and roll off, rather than absorbing the water. 

DWR is durable but doesn't last forever.  over time, washing a garment will remove some of the DWR.  so will chafing/abrasion, like you would get from contact with rocks or from a backpack hip belt and shoulder strap. 

The DWR plays an important role in a waterproof/breathable garment's ability to allow moisture to escape.  when water hitting the surface of a jacket beads up and rolls off, it keeps the pores of the membrane clear and able to allow smaller water vapor molecules to escape.  when the DWR stops working, the outer surface of the shell gets wet - and that can compromise the fabric's ability to allow moisture to escape.   

waterproof/breathable fabrics also become less efficient when exposed to dirt, or when they accumulate oils from a person's body through wear (which is inevitable over time, even if you aren't wearing the shell directly against your skin.

happily, there are pretty easy solutions to this.  periodically, wash your shell pants or jacket in a machine.  most detergents are probably fine; i use nikwax's tech wash because i think it is more gentle and less likely to remove the factory-installed DWR.  Usually, washing a garment and drying it (i hang dry all shells with waterproof/breathable membranes) restores much or all of the DWR properties and the ability to let moisture escape through the pores in the waterproof/breathable treatment or membrane. 

Much more occasionally, you may want to restore DWR by re-applying the coating.  There are products you can spray on or wash in.  when in doubt, follow the manufacturer's instructions for doing this.  for example, Gore recommends spray-on DWR treatments rather than wash-in.  (i prefer the wash-in because it's easier).  sometimes, a small amount of heat also helps restore DWR, like a short run through a dryer on a low setting, but some manufacturers frown on using dryers.  you could also apply heat with an iron, but that's risky b/c it can damage the fabric.

REI has a more detailed explanation of this:

Good tips!

Apparently, the cleaner you keep it, the better a DWR coating works. That being said, in heavy rain or a long, steady drizzle, I have yet to find a DWR fabric that will be absolutely waterproof without some kind of extra waterproof membrane underneath it.

One note; many of the DWR restoring wash-in formulas are severely affected by residual soap. Before using the chemicals, you'll want to rinse a number of times to get rid of any traces of soap. Then wash with the DWR solution and let the washing machine spin that out, but DON'T let it do a rinse cycle.

Toss straight in the dryer and bake for a while. 


Oh, good topic, thanks for bringing this up.

I have a Gore Tex TNF jacket that I bought in 1998.  It's in (it appears to be in) great shape, except that it seems to absorb water, rather than repel it.  I recently washed it with Nikwax Tech Wash, followed by a washing/soaking in the Nikwax Wash-In repellent stuff.  I'm less than satisfied with the results.

I would have followed the instructions, but there weren't any.  So I just filled a bucket with warm water, added "some" (no idea what the "right" amount is) of the Nikwax stuff, and sloshed it about for a while.  I used a light scrub brush for cleaning action with the cleaner.  For the wash-in repellent stuff I just sloshed it about, then let it soak for about 15 minutes.

Then I let it drip dry, and then ran it on low heat in the drier long enough to warm it up a bit.

I wore it in the rain later, and saw a slight improvement in repellency, but nothing like the "every drop beads up" effect I expected.

Were my expectations unreasonable or did I just do it all wrong?


one of the reasons i use tech wash rather than regular detergent is that i think it rinses easier and more thoroughly than regular laundry detergent.  also, re: 'baking' a waterproof/breathable jacket in the clothes dryer, check the labels.  i'm confident that the people who make eVent recommend against using a clothes dryer, whereas Gore says tumbling on warm is OK. 


you might want to try again.  and by the way, Nikwax isn't the only option; Tectron and Granger's also sell DWR spray or wash-in treatments. 

first of all, the instructions for Nikwax appear underneath the label, which you can peel back via one of the bottom corners.  fair to say the instructions aren't readily visible.  Second, if you bought the large "economy"-sized tech wash and tx direct, they don't come with the handy cap that helps measure the amounts.  however, the instructions give you exact amounts to use and how many garments each application can handle.  the instructions strongly imply that you should wash the garment in a washing machine rather than soaking in a bucket; same deal for washing in the DWR.  if you prefer spraying on, i'm not familiar w/that.   follow their instructions:   

tech wash instructions:

tx direct instructions:

tx direct spray-on instructions (Gore recommends this method rather than wash-in):

i cleaned and washed-in DWR to my Marmot jacket (5 year old gore tex pro shell) last night because it got pretty muddy yesterday and wasn't really beading up.  this morning, water was rolling off the jacket almost like a freshly-waxed car.   

Thanks, leadbelly, I'll look into this again.  I never thought to peel back the label for the instructions, quantities, etc. - good tip! :).  Not sure why I didn't find the info on the website though, d'oh!

As far as the 'baking' goes, I'm pretty sure I read (on here) that it's a good idea to tumble dry Goretex (on low heat, not hot) after using the wash-in water repellents - something about getting it permeate the fabric.  This jacket is old school Goretex, not eVent etc.

Thanks for the tips!

I have been treating hte many Gore-Tex products I have for years and some have now lasted 10+ years, though looking a little old.

Picked up the Grangers XT last night. Looks like you wash in tech wash, then spray on while it's wet. Next, you toss it in the dryer, still wet, and bake it.

I'd love to restore my old Sorel jacket; sure hopes it works.

update ?

peter1955 said:

... Next, you toss it in the dryer, still wet, and bake it.

 I knew I had seen this somewhere! :)

bheiser1 said:

peter1955 said:

... Next, you toss it in the dryer, still wet, and bake it.

 I knew I had seen this somewhere! :)

 Yeah. I actually read the instructions for a change!

It turns out I did most of what the instructions indicated, except I used warm (not hot) water for the TX. I will try it again with hot water and see how it goes.

careful with over washing.  This, the agetation, can prematurely wear the garmet.  Maybe wait until next time after the next trip.

January 20, 2021
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