How to measure the waterproofness of a garment?


Have you ever found yourself in the rain for several hours? Luckily, you were wearing a raincoat! But how does this one manage to keep you dry? Today, the editorial staff of Flotte deciphers the secrets of waterproofing (or how to ensure quality protection!).


Waterproof, water-repellent, waterproof, what's the difference?


To begin with, it is important to understand the nuance between these concepts that are too often confused. 

A cloth garment water repellent will act so that the drops of water that fall on you simply slide off its surface. The goal is to avoid water absorption by the fabric and, ultimately, to keep you as dry as possible.

The raincoat works in the same way, except that it also prevents the absorption of water when there is stagnation or pressure on the fabric of your garment. This detail, which may seem trivial, is actually very important and to be taken into account when looking for clothing to protect you from water. Indeed, a water repellent will not keep you dry as long as a raincoat since, under too much pressure (that of the handles of a backpack for example), the water is very likely to infiltrate under the fabric. and suddenly, to get wet (I.e.

Clothes sealed, for their part, are waterproof garments whose seams have been worked to keep the room waterproof. The seams are thus heat-sealed or ultrasonically welded. So yes, waterproof means that water will not enter. But a waterproof garment will also not allow the water vapors emitted inside your body to pass through. Thus, it is very likely that you will be wet under your jacket from your own perspiration (and not from the rain).


Find our collections of waterproof jackets men et woman !

How are garments waterproofed?


There are two techniques for waterproofing fabrics:


A water-repellent coating is applied to the inside surface of the garment. This material is useful because it effectively prevents water from penetrating the fabric, but also because it lets the heat and water produced by the body escape at the same time! 

If, at first glance, this technique seems to be a good solution, it is in fact only temporarily. Jackets or other products waterproofed by coating will allow you to cope with light rain. They will, for example, serve as a breakdown service in the event of a surprise rain. But during heavy downpours, these will not be the products that will protect you the longest.

In principle and generally, the coating method is used when a “bonus” function is added to a garment originally intended for another function. A coat, for example, is meant to keep you warm, but it can also be slightly waterproof to be more useful to its owner, more "go anywhere".

The membrane 

It is a hydrophilic film which is also applied to the inside of the garment. In this way, the membrane prevents water from penetrating from the outside to the inside, but it also allows all the water vapor produced by the body to escape! For example, your raincoat Amelot will leave the water, coming from all horizons, all its freedom!

You're going to tell us: so yes, like the coating in fact… Well no, the difference is that the membrane is more durable and more breathable, in addition to being waterproof. It keeps you drier for much longer than just coating, where the applied coating can break down more quickly over time. This way you will keep a garment waterproofed by membrane longer in your life.

This technique is therefore the most effective, but it is also worth it to be more expensive than the first.



Impermeability tests and the Schmerber index


Now that you know everything about the waterproofing techniques for clothes, we will explain to you how it works for tests impermeability. Because yes, making a fabric waterproof is good, testing its effectiveness and quality is better!

Again, there are several verification techniques. 


The first is the water column test. This test measures the resistance of the fabric under water pressure. Technically, how does it work? 

The waterproof fabric is simply placed under a column of water. This fills until the water pierces the fabric. After that, we can measure the number of millimeters of water reached in the column when the fabric is pierced, and thus give the result and therefore the impermeability index. 

When we talk about this index of impermeability, we say that the garment resist at, for example, 2000 mm of water, which is equivalent to 2000 Schmerber.


The second test is that of the shower (I.e. More effective than the first, it allows the entire garment to be tested. Indeed, you will quickly realize that if testing the fabric is useful and it gives a good indicator of the quality of waterproofing, on a jacket, there are also parts that are more exposed to water, more accessible and more sensitive: zips for example. 

So testing the entire product as if it were in heavy rain is the ultimate test of its true water resistance. The result obtained will in any case be the most reliable and the closest to reality.

The process is rather simple, the garment is placed under a shower-like device, hence the name, and sprayed with a large amount of water. This way, it is possible to see if water is seeping in, not only through the fabric, but also through seams, zips, and other sensitive places.



  • Understanding the Schmerber Index

If the name of this index may seem complicated, it is simply that it is taken from the name of its inventor: Charles-Edouard Schmerber. 

1 mm of water = 1 Schmerber 
1000 schmerber = it took 1 m of water in the column before it pierced the fabric


We can consider that a garment that has a resistance of 10 mm to water will keep you dry for about an hour spent in a good rain or in a surprise downpour. It will also keep you dry if a light rain persists all day for example.

On the other hand, in extreme conditions, subject to humidity and the presence of a lot of water (or if you plan to do Koh Lanta) prefer much more technical clothing and equipment, going to a resistance of at least 20 schmerber!  

remember that waterproofing is subject to living conditions : the pressure exerted on a waterproof fabric is likely to reduce its effectiveness! For example, like the pressure of the handles of a bag on a waterproof jacket, the pressure of a support or an object placed on a tent also threatens its impermeability. 

And yes ! If you're a seasoned camper, you probably already know this, but tents have varying degrees of water resistance on their floor and outside walls. The floor fabric must be more waterproof than the other edges because it is almost constantly subjected to the pressure of a mattress. So, to make sure you keep a dry groundsheet, it's important to pay attention to these details too when you go camping. ⛺️


At Flotte, our recycled raincoats are thought out and designed to keep you dry!


As you have understood, there are many methods for waterproofing your clothes, but also for testing them. And if all of them work and have the merit of existing, some turn out to be more effective than others! 

But suddenly, at Flotte, what are we doing ?


  • Our recycled and waterproof materials

We have been aiming to produce more eco-responsible fashion since our beginnings. So, if you know us, you are surely aware that the fabric of our raincoats is Made from 100% recycled materials, in particular recycled plastic bottles, food packaging or even used clothing ♻️

These are the main wastes that make up the rPET, the material we turned to for the design of our raincoats. rPET is also more simply called recycled polyester.

Learn more about rPET

Then, in order to waterproof our clothes, we apply a membrane on the inner surface of our raincoats. We chose the membrane because, more durable over time, it also promised greater efficiency against water and allowed your body to breathe more than with a simple coating. You are of course not immune to sweating a little by wearing it for a long time and in heavy weather, but that's what humans are all about! 💪

Our raincoats all have the same features: 

  • resistant to 10 mm of water
  • breathable at 10 g/m²/24h

They are therefore ideal for use in everyday life.


  • Impermeability tests

To make sure water doesn't seep through our raincoats (in which case they wouldn't 😅), we perform the two tests detailed above, namely: the test of the water column and that of the shower. It is in a French laboratory, in Lyon, that these tests are carried out. Thus, we do our best to know the best water resistance of our garments through tests, both on the main fabric, and on the garment as a whole.

The water column test allows us, first of all, to ensure the impermeability of our fabric. And that of the shower guarantees us, then, a total impermeability.


Plot twist : our raincoats are waterproof. They resist a pressure of 10 mm of water and are breathable, enough to be ready to face a downpour or a whole day of light rain! So, if you are looking for the perfect companion for your adventures (daily or a bit crazy), our colorful and recycled raincoats are made for you! 

PS: After reading this article, you can also brag about knowing everything about waterproofing 🌈


How to measure the waterproofness of a garment?

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