If you’re buying waterproof apparel, or clothes advertised as water resistant, you may have come across the abbreviation DWR. Those uninitiated in the minutia of outdoor fabric science may think it is a style code or some clever attempt at a brand for people who do things. But in reality, DWR stands for Durable Water Repellent, and it’s a finish that helps keep clothes dry. To learn a bit more about DWR, and how best to take care of clothing that uses it, we spoke with Ben Gerding, lab developer at Specialized.
DWR is not a fabric, but rather a chemical treatment that is applied to the exterior of waterproof, breathable fabrics. It “helps them bead up moisture and keep that top layer of fabric as light as possible,” says Gerding. “The goal of a DWR is to change the surface area of the exterior fabric at a micron level so as the water hits it, it has a more spiky shape so it beads up rather than dispersing and flattening out.”
While waterproof membranes like Gore-Tex live as a layer within an article of clothing, DWR lives on the exterior fabric. But since it is a treatment rather than a fabric, it can wear out. “Over the course of many years, the DWR washes out, it wears out. You’ll see the water start to penetrate the three top layers of fabric,” says Gerding, “It will start to look like it’s getting wet. Consumers will get concerned and think the waterproofing isn’t waterproof anymore.” In reality, the interior membrane that is actually doing the waterproofing is still working well, just the protection of the outermost layer has worn out.
If you hate this wearing out process, and how it makes moisture bleed out across the top layer of your jackets, and weighs the garments down, there are steps you can take to increase the longevity of DWR, and even ways to revive it.
First and foremost, avoid washing it. “You don’t want to wash your waterproof garments all the time; [the DWR coating] will wear out over time,” says Gerding. “You’ll see numbers like 80:20, something like that. That’s saying that after 20 washes it’s still 80-percent effective. Meaning 20-percent of the chemistry has broken down.”
The best way to avoid this is to avoid washing, which means making smart choices to keep your garments clean. “I’m always making sure I’m wearing something underneath a jacket, like a base layer or jersey top, to keep sweat from getting to that jacket as much as possible,” says Gerding. For bigger messes, consider spot cleaning. “For mud and things on the exterior the best way to make it last a really long time is to get a wet cloth and wipe it off.”
But it’s a fine balance. The DWR will also not work nearly as well when the jacket is properly dirty. “You’ve got oils and dirt and things that start to build up on the exterior face, and that starts to change the structure of the DWR,” says Gerding. “It makes it less slippery. The chemical finish starts to work a little bit differently.” Translation: your jackets start to get more wet.
So when your jacket starts to look a bit grimy, that’s when you want to give it a wash and a dry. And that dry cycle can even help revive a low performing DWR on a clean jacket. “The low dry cycle helps with the chemistry to reset it,” says Gerding. “Typically for me with my DWRs, if I’m starting to see that the fabric is starting to wet out or it’s not beading up after a few months of wear then I’ll go wash it and put it in the dryer.”
Not only will this help your jackets work better, it’ll help them last longer. “It can help extend the longevity, especially (important) with people trying to be as sustainable as possible,” says Gerding. And that’s something we can get behind.