Durable water repellent (DWR) is a coating added to the surface of a fabric to aid in waterproofing without sacrificing (and usually aiding to) breathability. The most frequent application of DWR in the outdoor gear world can be found in breathable rain gear and breathable water resistant shells. If the surface of the fabric were to “wet out”, breathability through that portion of the fabric would be severely compromised. DWR allows for water to bead and roll off the surface of the fabric, maintaining breathability.

Durable water repellent (DWR) is an application used to help water bead up and roll off of fabric surfaces.

Additional Uses for DWR

DWR is also used for footwear and other outdoor garments, as well as sleeping bags. When used on a non-waterproof product (a sleeping bag, hiking pants, or a hiking windshirt for example), DWR will not make the product entirely waterproof, but when the coating is fresh will make it highly water resistant and even brief light showers can be weathered before the treatment is overcome. This can be helpful when you're caught in a rain shower and it takes some time to stop and get that proper rain gear on. As a further example the DWR on some hiking pants (such as the Zion pants from Prana) will shrug off water from a quick stream crossing and dry faster, and the water from a spilled water bottle can be mostly brushed or quickly shaken off.

How Durable is DWR?

Though durable is in the name, the treatment is not permanent and is degraded by use, dirt, abrasion, and washing (how many washes it will last depends on the manufacturer’s application). DWR can be restored with heat – a clothes dryer or iron at a low-medium heat setting can work well. If this fails to revive the product, or you’d like to apply the advantage of DWR to a previously-untreated item, various spray-on DWR treatments as well as wash-in DWR products are available.

In Conclusion

DWR is an important treatment in regards to the performance of rain gear, and can be helpful when applied to other clothing items or gear as well – a sleeping bag with a good DWR will have a higher ability to stay dry when you get condensation falling on your bag from the top of your tent or brush up against wet tent walls, for example. In recent years manufacturers have begun to move towards PFAS-free DWR due to environmental and health concerns, and a PFAS-free DWR is a feature that may be desired when you're shopping for new gear or clothing that may have DWR applied.

Editor’s Note: This article originally appeared in Issue 5 of TrailGroove Magazine. You can read the original article here.