Rainwear: Durable Water Repellent (DWR) Care

Published October 17, 2017

This article is part of our series: Rainwear Basics

Three hikers wearing rain jackets on a wet day

Does it seem like your high-performance rainwear is giving you a damp, clammy feeling lately? Don't despair—and don't assume you need a replacement jacket. The fix is likely a simple one: Renew your jacket's DWR and it'll be performing like new again. Get in the habit of DWR renewal and your jacket will maintain peak performance for years to come.

What is DWR? Virtually all rainwear is treated with a DWR, or a durable water repellent finish. While a waterproof/breathable membrane will stop water from penetrating to a rain jacket's interior, a DWR is also needed to prevent precipitation from saturating the jacket's exterior. When the DWR breaks down, the rain jacket's exterior becomes waterlogged and heavy. That can leave you feeling wet and chilled or wet and clammy—and lead you to erroneously conclude that your jacket's waterproof/breathable membrane is failing.

What many people fail to realize is that DWRs diminish in performance for a number of reasons—the buildup of dirt and body oils or because of abrasion. Fortunately, a jacket's performance can be revived with proper cleaning, and can be bolstered by reapplying a DWR with a wash-in or spray-on product, an easy process you can do at home.

How to Test Your Jacket's DWR

Test your rainwear by sprinkling or spraying some drops of water on it. Does it bead up and roll off? Your DWR is in good shape. If you give the fabric a single strong shake, do most of those water drops fly off? Ditto.

If, however, the water sits on the fabric and that section begins to darken slightly, water is making its way into the fibers and wetting the fabric. It's time to revive your DWR.

Good news: Adding a DWR coating does not impair the performance of your jacket's waterproof/breathable membrane. Rather than coating a textile's entire surface, DWR coats individual fibers, leaving the space between the fibers open for breathability.

How to Revive a Rain Jacket's Water Repellency

  1. First step: cleaning. Washing away dirt and oils does much to restore DWR water-shedding abilities. You can usually find care instructions on the label or on the manufacturer's website. Technical fabric cleaners work best for this because they contain no additives that can interfere with garment performance.
  2. Next step: drying. Many jackets can go in a dryer on low or medium heat. Not all can so double-check your care instructions.
  3. Next step: applying heat again. This is key to DWR revival and should be done every time you launder your jacket. After washing, place it back in the dryer on low or medium heat for 20 minutes to reactivate the DWR finish. Warm-iron alternative: If you don't have a clothes dryer or your care instructions require hanging to dry, you can use a clothes iron to revive the DWR. Set the iron on no steam, with the heat setting on warm, not hot. Then iron your garment, making sure you have a thin towel or cloth between it and the iron as you do so.

How to Apply New DWR

If the steps above—cleaning, drying and applying heat—aren't enough to revive your DWR (i.e., rain still soaks into the exterior fabric of your jacket), it's time to apply a new DWR coating.

This step eventually becomes necessary because DWR can be abraded off of high-contact areas like the cuffs and collar, or by the jacket rubbing against natural surfaces like rocks or brush. Your DWR can be reapplied via a spray-on or wash-in product that essentially coats all of the DWR "bald spots" on your rainwear. You can do this as many times as needed over the years.

Follow the manufacturer's instructions for the type of DWR replenishment product you choose. The process often involves washing the jacket with a special additive-free tech wash first, then washing in or spraying on a new DWR treatment. Reviving DWR with heat is also wise (step 3, above) because it restores the performance in areas where the jacket's original DWR finish is still intact.

Newer Gear Needs More DWR Care

As DWR finishes have evolved, they've also improved the chemistry from an environmental standpoint. The trade-off, though, is that environmentally preferable DWRs are also slightly less durable. Thus regularly washing and reviving the DWR on a new jacket is now even more critical to maintaining your rainwear's performance.

How DWRs Work

DWR works by increasing the "contact angle" or "surface tension" created when water touches a textile. Basically, a high angle of contact creates a microscopically "spiky" surface that suspends water droplets on the outer fringe of the fabric.

An optimized DWR keeps droplets in a rounder shape—like a dome-shaped bead. The rounder the droplet, the easier it rolls off the fabric. A low angle of contact permits droplets to assume a flatter shape, one that can spread out like a splotch, cling to the fabric's surface and eventually seep into it.