PRODUCT FACTS
WATER REPELLENT

What does it mean when it says that a garment is waterproof and breathable? Here are some answers for you.

When we’re outdoors in the rain and wind, we want clothing that keeps us dry and warm yet allows us to move freely without getting sweaty and clammy. All kinds of fabrics, from the ultra-thin stretchy to the more sturdy, classic rainsuits, are said to be both waterproof and breathable. How does that work?

Let’s start with waterproofness. Fabric must normally have a waterproof rating of 3,000mm (3m) or more. Sounds simple enough, doesn’t it? Well, it’s not really that straightforward. There are lots of different test methods and each has different set-ups and procedures. So unless you can be certain that the same test method was used, it is tricky to compare figures.

The water column test is the most common method.  This used to involve pouring water into a tube and then measuring how much pressure the fabric, pulled tight under the tube, could withstand. The principal is still the same except that the tests are now automated. The EN ISO 811 & JIS L 1092 are examples of the test method. The rate at which water pressure is applied can differ in each test, producing very different figures.
It is the same for breathability, which can also be tested in numerous ways. The most common methods test the amount of water vapour that passes through fabric. Under two such tests, the JIS L 1099 & ASTM E96/E96M, the values should be high. Or fabric can be tested to measure its vapour resistance. In these tests, like the EN ISO 11092, the values should be low.

So the same fabric, tested in different ways, can achieve completely different performance values.
Fabric is laminated with a membrane to make it waterproof and breathable. Explained simply, laminating is the adhesion of a thin plastic film to the fabric. There are two main types; one has tiny microscopic pores that let vapour out but are too small to allow water droplets to come in. The other type has a material in the lamination film that wicks moisture from inside the garment and transfers it to the outside. This is most suitable for cold-climate clothing, as the wicking effect requires the temperature to be colder on the outside of the garment.
In both types, the lamination film makes the fabric waterproof.
Applying a coating of plastic-based material to the back or front of the fabric is another way of making it waterproof.

The face side of the fabrics is usually reinforced with a water-repellent finish to maximise their waterproofing qualities. This ensures the raindrops roll off the surface and stops water from being absorbed by the outer fabric, thus preventing clothing from becoming heavy and cold. It also helps to repel dirt, which can otherwise cause water to seep through the membrane.

We have tested water resistance and the ability to breathe on our materials 1977 & 1987 with different test methods.
As you can see from this chart, we get different results depending on which method we choose.

WATER RESISTANCE

EN ISO 811 EN ISO 811 JIS L 1092 B
CommentWater pillars tested according to the requirements in EN343. Pressure increase rate 10 cm/min.*Water pillar. Pressure increase rate 60 cm/min.Water pillar. Pressure increase rate 100 cm/min.
1977≥20000 Pa/ ca 2000 mm (kl 4) 15 000 mm 17 000 mm
1987 ≥20000 Pa/ ca 2000 mm (kl 4)11 000 mm22 000 mm

VENTILABILITY

EN ISO 11092 JIS L 1099 B1 ASTM E96/E96M
CommentSteam resistance tested according to requirements in EN343. (kl4= ≤15).Steam passageSteam passage
1977 20 000 g/m 2/24H4 000 g/m 2/24H
198731 000 g/m 2/24H4 000 g/m 2/24H

*The test is usually stopped at 20 000 Pa which is the maximum limit for EN343, class 4.
The values only refer to laminated textile.

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