What is the zipper test
Waterproof, water-repellent, waterproof - what's the difference?
Sometimes it is really not easy in the confusing jungle of outdoor product properties. But in order to choose the right product, one has to understand the details that the manufacturers advertise with. In order to give you a little help, we dedicate this article to the topic of rain protection. More precisely: the difference between water-repellent and waterproof clothing. And what is this water column that is always mentioned in rain jackets?
What is the difference between “waterproof” and “water repellent”?
Waterproof means that the material is so dense that no water can get through. You should stay dry here, no matter how long you are outside in the rain. In the case of really waterproof jackets, only the surface is completely soaked, but the clothing inside otherwise remains dry and protected by the special waterproof ePTFE or PU membrane and laminates.
If a jacket or pants is water-repellent (other industries also refer to their products as water resistant), then the water or dirt rolls off the surface and is prevented from penetrating into the interior. In continuous or heavy rain, however, it cannot be ruled out that the inside of such a water-repellent jacket will get wet over time.
In order to get a clear definition and a comprehensible guideline as to whether a jacket or pants is waterproof or water-repellent and the customer can orientate himself accordingly when buying outdoor clothing, the textile industry has defined international standards for the so-called hydrostatic water column.
What does the hydrostatic water column mean and how is it calculated?
The hydrostatic water column describes the height of a theoretical water column that presses on a tissue surface and is specified in millimeters.
An example: a water column of 10,000 millimeters (i.e. ten meters) corresponds to a pressure of 1 bar.
When it comes to waterproofing, it always depends on the pressure that is built up on the fabric. This pressure increases accordingly if, for example, the wearer of the fully loaded rucksack presses on the already wet jacket surface. Even when the wind whips the rain against it, the pressure of the water increases, which the jacket has to withstand.
Here some examples:
- A person who sits with their body weight in the wet grass creates a water pressure of approx. 2,000 millimeters of water column, when kneeling in the grass it is already approx. 4,000 millimeters.
- This calculation is irrelevant for a tent cloth or canvas because nobody is sitting or kneeling on it. Therefore, a water column of 1,000 millimeters is absolutely sufficient, depending on the application.
- Exactly the same applies to a trekking umbrella, while the tent floor and tarpaulin should already have a water column of at least 5,000 millimeters in order to be really waterproof.
- On the other hand, rain or ski pants that are used to kneel or sit on wet surfaces become really waterproof from a water column of 15,000 millimeters.
- A hardshell jacket designed to carry a heavy rucksack becomes waterproof from a water column of 20,000 millimeters. Without a backpack, jackets with a water column of 10,000 millimeters are usually sufficient.
By the way: According to international standards, the limit at which a water-repellent jacket becomes a waterproof jacket is a water column of approx. 800 millimeters.
What does "permanently waterproof" mean?
In order to ensure that water cannot penetrate anywhere in waterproof clothing, all seams and zippers must be sealed. The specially welded seams, hems and water-repellent zippers then also have to withstand washing machines. Of course, this does not mean that unsealed jackets are not waterproof, but the risk that seams and zips let water droplets into them - especially over time and when they become more brittle - can exist.
Does the clothing lose the property of being waterproof at some point?
It would not be correct to claim that waterproof clothing remains 100 percent waterproof over time, as the membrane can be damaged over time, and dirt or sharp objects can cause leaks. In addition, waterproof hardshell jackets and trousers are often additionally impregnated. Because waterproof functional clothing can only function properly if the DWR finish is intact.
The water-repellent DWR treatment prevents the upper material from absorbing water and getting into the intermediate layer. Because even if the moisture does not penetrate, the clothing can become heavy. In addition, a soggy upper material prevents moisture from being transported away from the inside.
This means that the additional impregnation of waterproof materials has two advantages:
- The water density is increased
- It prevents the jacket or trousers from becoming too heavy and functionality deteriorating.
Test to check whether the clothing is still water-repellent: take a water bottle, spray on clothing, see whether the water is absorbed or pearls off. By the way, the beading off is called the "lotus effect".
What does "permanently water-repellent" mean?
Permanently water-repellent materials are usually impregnated, i.e. they are treated chemically or thermally. The most common - but by no means the only (!) - treatment here is D.(urable) W.(ater) R.(eppellent) finish impregnation. However, these, as well as other impregnations, wash out over time. It is therefore recommended to re-impregnate jackets and trousers regularly or reactivate the DWR treatment. This will ensure that water droplets will continue to be on the surface
roll off and do not penetrate inside.
How do you wash and care for waterproof / repellent clothing?
If your waterproof clothing needs to be washed again, you can clean it in the washing machine with a special detergent or mild liquid detergent - but without any additives (!).
Which maintenance measures are exactly permissible or recommended depends on the material and structure of the climate membrane used. Porous membranes should be cleaned regularly to maintain breathability. Non-porous membranes only need to be washed if the outer fabric is really dirty.
Our washing instructions examples for ...
If you want to impregnate the freshly washed rain jacket afterwards, our instructions "Impregnate rain jacket - this is how it works!"
All rain jackets that keep you bone dry can be found here at Bergzeit:
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