Water-repellent treatment: the great forgotten item in technical clothing

Imagine water running down fabric.

If I talk to you about technical clothing or waterproof clothing, this is the first image that comes to mind.

And it is often associated with the name of a high-tech membrane, which pushes the limits of waterproofing and breathability even further, in order to justify a price of several hundred euros.

However, if the water runs off, and if it gives this impression of “bouncing” on the fabric, the membrane is not responsible , since in fact, it is located and laminated (=glued) under the outer fabric.

No, what prevents water from soaking into the fabric is the water-repellent treatment applied, also called DWR in English for “Durable Water Repellent”.

An important feature of any garment intended to cope with downpours, but one that is often relegated to a single line of text on product pages.

Whereas without water repellent treatment, the outer fabric would be soaked with water, and perspiration cannot pass through the membrane. This is very well explained in this video from Nikwax:

The problem is that water-repellent treatment is often wrongly confused with waterproofing , when in fact they are two different things.

We will look at this in detail as well as possible solutions when the water-repellent treatment fades.

If there is only one thing to remember from this article, it is this sentence.

Let me explain…

A water-repellent treatment is a chemical (not mechanical) finish applied to the fabric to prevent it from becoming soaked when it rains: we are talking about a hydrophobic fabric.

The opposite is a hydrophilic fabric, which absorbs water (think of a sponge or a drop of water falling on a piece of cardboard!).

In the case of a waterproof fabric, it does not let rainwater pass through (at least to a certain extent) when it falls on your jacket because there is a membrane bonded behind the fabric. The membrane is an additional, invisible element that guarantees the waterproofness of a material. Thus, a water-repellent garment does not have a membrane. A waterproof garment does.

So a fabric can:

• be water-repellent but not waterproof (i.e. water can run off it and cannot have a waterproof membrane despite everything)
• be waterproof but not water-repellent, which is of no interest because it prevents the membrane from wicking away body moisture,
• be water-repellent and waterproof: this is the case for most hiking jackets made from Gore-Tex, eVent, and other well-known membranes.

(not to mention that a membrane can quickly wear out and delaminate in certain cases, I invite you to watch my video on waterproofing to go further on this subject, with the photo of my young father as a bonus)

But there is a huge benefit to having a water-repellent AND non- waterproof fabric: it is much more breathable than a waterproof membrane because the humid air generated by your body can escape very easily. This is also the philosophy of the PCU (Protective Combat Uniform), the clothing system of the American military.

And a water-repellent but non-membrane fabric is also less expensive , and with more variety in compositions and textures.

This is the case, for example, with Ventile, a 100% cotton fabric that I love and which resists bad weather wonderfully well.

However, water-repellent treatments are not a miracle solution either; they also have their limits.

After a while, if exposed to prolonged rain, the water-repellent treatment is no longer sufficient to stop the water , and it will still pass through the fibres.

At this point, two possible cases:

• there is a membrane and you stay dry,
• there is no membrane and water penetrates your jacket. I reassure you, it's nothing dramatic!

Estimating when water will wear out a water-repellent treatment is very difficult, because it depends on many factors: the intensity of the rain, the age of the piece, its maintenance, the quality of the water-repellent treatment, etc.

But in my experience, a good water repellent treatment allows you to hold out for 20 minutes in a moderate downpour, which is more than enough for 99% of urban travel. Some Ventile users even talk about an hour or two in the rain while remaining completely dry.

If the jacket does get wet, don't panic, it will dry quickly as soon as the downpour stops.

So I repeat, a water-repellent treatment does not necessarily mean that the garment is waterproof, but what you lose in waterproofness, you gain in breathability (I underline and put this sentence in bold because it is essential to understand).

Before we get into the practical side, I have to address a chemical component that has long tarnished the image of water-repellent treatments: PFCs for PerFluoroCarbide.

For a long time, PFCs were used to make clothing water-repellent, especially C8. But a major problem arose: they were so effective that they did not degrade in nature, and now PFCs have invaded the planet , including in very remote areas.

And because C8 is nearly impossible to break down, it can accumulate in organisms that unintentionally absorb it, including humans.

So it was banned (but is reportedly still allowed for military applications, although I can't find confirmation of this rumor).

Along came C6, which accumulates a little less in the body, but is also about to be banned. Which has sent Gore-Tex into a frantic race to find a more responsible alternative .

The subject of PFCs is very vast , and I recommend this article from the Green Session to go further or the dedicated page from Nikwax (I will come back to this brand later).

But fortunately, today water-repellent treatments based on C6 are increasingly rare. And as a clothing designer, I no longer see them from our usual suppliers, where all technical fabrics are “PFC Free”. In less than ten years, there has been considerable progress.

The only drawback: they are less effective than the C8 or the C6 but Nikwax has recently presented a very promising industrial solution, the Nikwax Direct.Dry:

The promises are tempting:

• a score of 100 (the maximum score) in the water repellency test,
• high resistance to washing: a score of 80 after 20 washes, and which returns to 100 after a special wash by the individual that I explain later,
• and as always with Nikwax, an exemplary environmental impact.

Now let's get down to business: what to do when water no longer bounces off the fabric and the water-repellent treatment is no longer as effective?

Bad news: no matter how good the water-repellent treatment is (even if it is military grade), it will wear out over time . Water-repellent treatment is an experience of the impermanence of things: it will inevitably end up going away, just like raw jeans develop a patina and lighten over time.

Yes yes, it even affects the most expensive Gore-Tex jackets, they end up no longer being water-repellent either.

The areas prone to friction on the shoulder straps or back of a backpack are the first to be affected.

What does a water-repellent treatment that needs to be renewed look like? It's very simple: all the water drops that fall on the jacket are absorbed by the fabric instead of "bouncing off", as if you were dropping water on a cotton T-shirt.

Fortunately, there are solutions!

I am writing these words because I have already spoken with customers who thought that the water-repellent treatment lasted for life.

This is not the case and it is possible to restore the water repellency of a garment.

To do this, you need to maintain your clothing with Nikwax products, it is the reference brand for maintenance products intended for outdoor clothing while being as responsible as possible . For example, they have products specially designed for wool clothing , with down , base layers , cotton, or leather .

In this video you will find the instructions from Nikwax:

Note that TX.Direct is available in spray form, which can be practical for locally applying the water-repellent treatment to a garment whose lining must remain absorbent, for example for very specialized garments such as Buffalo Shirts.

Paramo, the waterproof clothing brand owned by Nikwax, also offers a comprehensive FAQ on waterproof clothing care.

If you really want to dig deeper into the subject, there are a ton of tutorials on Youtube with the keywords “use Nikwax”, “wash waterproof jacket” that will explain everything to you!

That’s it for this guide to water-repellent clothing, the difference with waterproofing and the importance of maintaining it correctly.

I am available in the comments if you have any questions!