How do you measure the waterproofness of a hiking jacket?

Coating, membrane, water repellent properties, etc. Does that mean anything to you? These are all elements that will affect the waterproofing of your waterproof hiking jacket. So how do you measure the waterproof rating of this garment that you will use on your wet hikes? We explain all!

Your hiking jacket (sometimes called "hardshell") is recognised as waterproof when it can stop rain from getting through, thereby protecting you from the elements. But there are different levels of impermeability, and different tests to measure them.

To get a clearer understanding, read this article to find out how to measure the waterproofing of a hiking jacket!

Waterproofing and water-repellent properties: what's the difference for your hiking jacket?

What is the waterproofing of a garment and why it should not be confused with the water repellent properties? Let's look at the difference right away, in order to avoid getting in a muddle!
The water-repellent property of a fabric is simply its capacity to make water run off its surface, without absorbing it. Conversely, the waterproofing of a fabric is its capacity to prevent water (rain, snow, dew or humidity) from getting inside a product.

Whether we are talking about a water-repellent or waterproof product, it is characterised by a "chemical" treatment applied to the component of the product. As you now know, a water-repellent fabric has the ability to make water "bead" on the surface. The more the water runs off the surface without soaking into the fabric, the more it is waterproof. Consequently, the garment does not soak up water and stays lightweight. This is due to treatment on the outside of the component.

A waterproof fabric is a water-repellent component to which extra protection has been added. This is what prevents water from getting inside the garment, even if water should stagnate or be sprayed on the fabric (e.g. backpack). This is achieved by treating the outside of the fabric, but also by waterproofing it from the inside. There are two different types: the coating and the membrane.

HOW SHOULD YOU TREAT YOUR JACKET TO MAKE IT WATERPROOF?

Two techniques are traditionally used to make a garment waterproof: the coating and the membrane. Don't run off, it's simpler than it sounds!

1/ The coating
A coating is a waterproofing material (a kind of paste) that is spread on the inside of the fabric. It prevents water from seeping into the garment from outside but releases the moisture produced by the body during exertion.
Its purpose? To give you a back-up solution if you get caught out by a few drops of rain. These products are generally designed for another purpose, e.g. keeping you warm. While their water repellent feature is a "bonus", they are not really designed to protect you from the rain during a hike.
A jacket, that is only water repellent (without being waterproof), is not meant to provide a high level of protection and is only suitable as a "backup" solution. If there's a chance of rain, remember to take a 3rd waterproof layer.

2/ The membrane
As for the membrane, it is a film that is applied on the inside of the fabric. This hydrophilic membrane blocks water coming from the outside while wicking away the perspiration produced by the active body. The membrane is laminated to the inside the component, making it more flexible and more durable than a coating.

THE WATER COLUMN TEST to test the fabric

The first test that is traditionally used to assess waterproofing is the water column test. This test measures the resistance of a fabric to water pressure.
The test results are expressed in terms of the height of a water column in mm or mm Schmerber (named after the textile industrialist Charles Edouard Schmerber who created this measurement method).

Waterproof ratings are determined by a fabric's resistance to water pressure, expressed in terms of the height of a water column in mm: The higher the water pressure, the more waterproof the fabric. A component with a 10,000 mm waterproof rating, i.e. it can withstand the pressure of the 10,000 mm column of water. Which is also the equivalent of 10,000 Schmerbers.
1 Schmerber = 1 mm water column = 0.1 mbar.

At Decathlon we've successively applied two standards to determine waterproof ratings:
- The ISO DS006 standard: a column is filled with water at a constant pressure of 60mbar/min. The test concludes once 3 drops of water have managed to seep through the fabric.
- Since 2021, we have applied the JIS L 1092 standard to test all our Quechua & Forclaz products as it's the most commonly used in the outdoor equipment market:a column is filled with water and the pressure is rapidly increased up to 1000mbar/min. The test stops when the pressure of the water rips the fabric.
After testing, our engineers then measure the height of the water to determine the component's waterproof rating.
Depending on whether you're using the ISO or JIS standard, the height of the water column expressed in mm (Schmerbers) can vary for the same waterproof rating.

The average pressure of rainfall is between 1,000 and 2,000 Schmerber. A garment is therefore deemed waterproof if it can withstand the pressure of a 1.3 m (i.e. 1300 mm) high column of water in accordance with the ISO 811 standard). But bear in mind that a jacket made of a fabric with a waterproof rating of 2000mm Schmerber will indeed protect you from the rain, but maybe not from a long downpour or thunderstorm. Indeed, the higher the Schmerber number, the more the material is waterproof.

Please note: the quality of the material used is very important, because the waterproof rating of a new jacket made in a low-quality component will drop after it is washed.
At Decathlon, we ensure that the waterproof rating of our products remains the same both before and after washing.

The shower test to test the jacket from every angle

In our opinion, this is the most representative test because a product made of a highly waterproof fabric can leak water through its seams, flaps, zips, etc.

In this test, the products are placed in a shower to test their overall waterproof rating.

Waterproofing and water repellent properties: what is the difference?

What is the waterproofing of a garment and why it should not be confused with the water repellent properties? Let's look at the difference right away, in order to avoid getting in a muddle!
The water repellent property of a fabric is simply its capacity to make water run off its surface, without absorbing it. Conversely, the waterproofing of a fabric is its capacity to prevent water (rain, snow, dew or humidity) from getting inside a product.

Whether we are talking about a water-repellent or waterproof product, it is characterised by a "chemical" treatment applied to the component of the product. As you now know, a water-repellent fabric has the ability to make water "bead" on the surface. The more the water runs off the surface without soaking into the fabric, the more it is waterproof. Consequently, the garment does not soak up water and stays lightweight. This is due to treatment on the outside of the component.

A waterproof fabric is a water-repellent component to which extra protection has been added. This is what prevents water from getting inside the garment, even if water should stagnate or be sprayed on the fabric (e.g. backpack). This is achieved by treating the outside of the fabric, but also by waterproofing it from the inside. There are two different types: the coating and the membrane.

How should you treat your jacket to make it waterproof?

Two techniques are traditionally used to make a garment waterproof: the coating and the membrane. No need to fret, it's easier than it sounds!

1/ The coating
A coating is awaterproofing material (a kind of paste) that is spread on the inside of the fabric. It prevents water from seeping into the garment from outside but allows the water vapour produced by the active body to escape.
Its purpose? To give you a back-up solution if you get caught out by a few drops of rain. These products are generally designed for another purpose, e.g. keeping you warm. While their water repellent feature is a "bonus", they are not really designed to protect you from the rain during a hike.
A jacket, that is only water repellent (without being waterproof), is not meant to provide a high level of protection and is only suitable as a "backup" solution. If there is a risk of rain, remember to bring a 3rd waterproof layer.

2/ The membrane
As for the membrane, it is a film that is applied on the inside of the fabric. This hydrophilic membrane blocks water coming from the outside while wicking away the perspiration produced by the active body. The membrane is laminated to the inside the component, making it more flexible and more durable than a coating.

In addition to this, there is the construction of the component, which is evaluated according to its layers.

The2-layer component: The membrane is glued only to the outer fabric; the inner protective lining is free. This construction is used for the more comfortable jackets.
The 2½-layer component: The membrane is glued under the outer fabric and protected inside by a fine film. This construction is used for the more lightweight jackets.
The 3-layer component: The membrane is glued between the outer and inner fabric

How to measure the waterproof rating of a hiking jacket: there are two different types of test

the water column test

The first test that is traditionally used to assess waterproofing is the water column test. This test measures the resistance of a fabric to water pressure.
The test results are expressed in terms of the height of a water column in mm or mm Schmerber (named after the textile industrialist Charles Edouard Schmerber who created this measurement method).

The waterproof rating is measured by the fabric's resistance to water pressure, expressed in terms of the height of a water column in mm (test based on the ISO 811 standard). The higher the water pressure, the more waterproof the fabric. A component with a 10,000 mm waterproof rating, i.e. it can withstand the pressure of the 10,000 mm column of water. This is also equivalent to 10,000 Schmerbers.

1 Schmerber = 1 mm water column = 0.1 mbar.

The average pressure of rainfall is between 1,000 to 2,000 Schmerber. A garment is therefore deemed waterproof if it can withstand the pressure of a 1.3 m (i.e. 1300 mm) high column of water in accordance with the ISO 811 standard). But bear in mind that a jacket made of a fabric with a waterproof rating of 2000mm Schmerber will indeed protect you from the rain but maybe not from a long downpour or thunderstorm. Indeed, the higher the Schmerber number, the more the material is waterproof.

Please note: the quality of the material used is very important, because the waterproof rating of a new jacket made in a low-quality component will diminish after washing.
At Quechua, we make sure that our products can claim the same waterproof rating before and after washing.

The shower test

In our opinion, this is the most representative test because a product made of a highly waterproof fabric can leak water through its seams, flaps, zips, etc.

In this test, the products are placed in a shower to test their overall waterproof rating.

What level of waterproofing for what use?

Following this test, we can therefore establish the following classifications:

- A product with a score of 2 protects the user from a light shower i.e. 6mm of rain in 1 hour (which corresponds to the average rainfall for a month of rain in the lowlands in France);
- A product with a score of 3 protects the user from a downpour i.e. 12mm of rain in 2 hours,
- A product with a score of 4 protects the user from a storm i.e. 30mm of rain in 3 hours,
- A product with a score of 5 protects the user from a violent storm i.e. 1.8cm of water in 4 hours.

You will find these scores in the technical benefits indicated on the data sheets of our Waterproof Jackets on our website

Pénélope

An enthusiast hiker and Quechua employee

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