Nearly every piece of technical outerwear today is treated with a Durable Water Repellent (DWR) finish before leaving the factory.
The DWR treatment is the first line of defense against wet weather conditions and prevents the face fabric from becoming saturated. When you see water beading up and rolling off your Gore-Tex jacket or down puffy, that’s actually the DWR technology at work.
DWR is a polymer applied to the face fabric that creates microscopic pegs, or hairs, that protrude from the fabric. (You didn’t know that you were bristling like a hedgehog in your new ski jacket, did you?) These pegs encourage the water droplets to band together and roll off, instead of spreading out along the face of the fabric and soaking through.
In the graphic above, the pegs created by the DWR coating are represented in red above the face fabric. As your can see the water droplets, represented in blue, bead up and roll off the coating.
However, the effectiveness of a DWR treatment becomes compromised over time by exposure to dirt, grease, sunscreen, smoke, bug spray, hair, etc. The little pegs lose their perkiness, and start getting clogged, flattening out, and losing their ability to ward off water. If you notice that rain or snow is saturating your jacket instead of rolling off it, the DWR treatment needs some maintenance. It’s a common misconception that technical outerwear, like Gore-Tex rain pants, for example, should be washed as little as possible; that couldn’t be further from the truth. Regular washing, if done correctly, actually reactivates the DWR treatment so it works the way it’s supposed to.
To clean a garment, place it in a front-loading washing machine (the agitator in older top-loading machines could damage the garment, especially if it’s a down puffy) and set it on a warm cycle with a low spin. It’s important to use the right detergent: ideally, a liquid detergent designed specifically to clean technical garments, such as Nikwax Tech Wash. Commercial liquid detergents will work in a pinch, too, but keep in mind that they may contain perfumes, conditioners, bleaches, softeners, or other waxes or oils that will adhere to the surface of the garment. These residues will attract water and thus limit the effectiveness of the DWR, so be sure to rinse the garment twice to get as much out as possible.
Once the dirt and contaminants have been washed out, heat is required to reactivate the DWR. You can either dry it in the dryer or hang-dry it and then tumble it in a warm dryer for 20 minutes. If the garment’s cleaning instructions prohibit the use of a dryer, you can apply heat by passing a warm iron over the surface of the fabric; just be sure to place a towel between the garment and the iron to avoid damage.
Regular cleaning will help your garment perform better, but there will come a point when you might need to restore the DWR. Wash-in and spray-on products are available that will quickly and effectively get your garment performing the way it was meant to. Simply wash in or spray on, apply the heat treatment, and get outside.