DWR: What is it and how does it keep you dry?

One of the terms that is DWR, has become something of some unique specifications and selling points from shoes to wear gears and what not in the recent years. But the questions that arises in our minds are like, what is DWR coating? What does DWR actually mean? Is DWR waterproof or water resistant? And whatever DWR is, do we need it or not?

In the article below, we will try to answer all the questions above and provide further information about the workings and usefulness of DWR, why you need it, how it’s measured, and how to care for garments with a DWR.

What Is DWR?

The abbreviation of the term DWR is exactly “Durable Water Repellent” and it also belongs to a layer that is applied to any product that needs to be made water resistant during its production to add water resistance properties. DWR is usually used in combination with waterproof breathable coatings such as Gore-Tex or an Event layer on the interior, a DWR finish is expected to prevent the exterior of any product that is developing saturation and thus inhibiting the garment’s overall breathability and water-resistant properties.

A Very Brief History Of DWR

DWR finishes or coatings is not something that is considered as a new idea and it was found from some past ancestor in the grease form taken out from the animal fats and oils such as linseed oil that was used by early hunters, fishermen, and tribes such as the in units to apply coating to the tents, sails, and clothing etc.

But if we talk about the modern chemical-based DWRs they are slightly different then the traditional ones, they were first used right after the introduction of GoreTex in 1969, when it was revealed that the waterproof lining in any three or two-layer garment would perform way better if it is used in combination with an exterior coating that was used to prevent the outer layer that was becoming soaked with water.

How Do DWRs Work?

The question in everybody’s mind is what does water repellent really mean and how does DWR defend you from the elements? DWR fabric actually work by letting the fabric on which they are applied to not soak liquid but to shed it upon applying. From the direct eye, this effect seems like water droplets beading up and rolling off the surface of the material.

With a more detailed and microscopic level, this process is far more elaborate, and this process totally depends upon the angle of contact between water or any other wet substance and the DWR applied fabric. For a person who does not know much about this process, a DWR layer increases the contact angle between the fabric’s surface and dampness, it is seen that the higher the angle of contact the better and low contact angles result in the drop that is spreading out on the surface and soaking into the fabric, on the other hand with a higher angle of contact the water forms into a round bead or droplet and rolls off.

DWR Ratings

In case you want to evaluate the ratings for the DWR you will have to do the simple spray test which may sound fancy but is the simplest test among all. For this process you have to follow the simple steps like, water is sprayed onto the fabric and then the degree or level or water repellency is evaluated visually by measuring the quantity of the water that is still standing on the fabric’s surface. Ratings or scores are produced in points established by the percentage of fabric with no water sticking to it. For instance, a product with a 90 point rating means 90% of the fabric had no water sticking to it after spraying.

If you want to test durability of the DWR, the same spray test is repeated after several numbers of washes, which is suggested in the second number given in any rating. For instance, a rating of 80/20 shows that the fabric retained an 80-point rating after 20 washes, or it was 80% water-free in the spray test following 20 washes.

What DWR Rating Do we actually Need?

It is quite different from hydrostatic head, DWR ratings, if given at all, are usually contained in the small print of a product’s measurements.

Below is a guide to interpreting any ratings you must know for your knowledge.

  • 80 points/10 washes – The bare minimum for classification as DWR in most outerwear
  • 80 points/20 washes – The usual DWR rating for water-resistant products for most outdoor industry brands
  • 80 points/50+ – Extraordinary water repellency, usually used in either very high-end waterproof products or garments which lack a waterproof membrane and depend on only on DWR for water resistance.

Problems with DWRs

All of the people that are planning to buy DWR products should be well aware of the fact that these also comes with many disadvantages, most commonly the use of chemicals, high maintenance issues, and the necessity for reapplication of the DWR coating. ​

Chemicals that are being used in DWR.

Even Though past few years many of the companies committed to completely removing or decreasing the use of many toxic and harmful chemicals from their garments, but a recent study issued in 2015 found that 36 out of 40 outdoor products do contain toxic and harmful per fluorinated compounds (PFCs) in them.

Per fluorinated compounds, which have been related to many health issues such as reproductive issues, developmental problems, and cancers as well, are due to the chemicals that are being used in many DWR finishes that do not destroy on their own, are very slow to remove from humans and other living beings, and in many cases last forever in the environment.

In the year 2015, almost 200 scientists contracted the Madrid Statement, which underlined the dangerous and harmful effects that were caused by PFCs and called for the poisons to be stopped using in the products. Even Though some big and named brands were really smart to perform accordingly, but many other brands such as the North Face and Mammut kept on using PFCs in newly issued products, in spite of having promised to discard the use of such harmful chemicals by 2020.

Maintenance & Reapplication

Not at like our daily usual waterproof layers such as Gore-Tex, eVent, or Pertex Shield+, the water-resistant component that is used in DWR products are more durable and definite. After usind for a longer period of time and keep on washing, many of the factors such as dust, grease, sweat, abrasion, and weather exposure can and will decrease DWR productivity and effectiveness.

For the purpose of reducing the weakening of a DWR effect on the fabric, frequent washing with additive-free a DWR detergent is suitable and advised. After every 10 to 20 washes, again applicating the coating with a spray-on treatment such as Revivex or Nikwax TX Direct Spray or wash-in treatment such as Nikwax TX Direct Wash-In will rebuild the coating’s effectiveness to levels comparable to those at the time of purchase.

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