Waterproofness - what does it actually mean?
Waterproof is a relative term. In this article we’re going to teach you all about how we measure the waterproofness of our hiking clothes and how we rank them.
When purchasing a new shell-layer, the waterproofness of it is one of the main functions you search for - this is where this mystical term “water column” shows up and we’re gonna explain what it means.
First some basic facts. If you’re looking for a 100% waterproof garment for yourself or your child, classic rubber rain clothes may come first to mind. The downside of these types of rain clothes is that breathability is non-existent. This means that you will get sweaty and damp even if you’re doing low impact activities, and as you increase activity level this problem will only worsen.
The alternative to these classic rain clothes is shell garments. Shell garments are breathable since they have a laminated membrane on the backside of the outer fabric. The outer fabric combined with the membrane creates a shell-like material. This material releases air but not water - that’s why we say that shell materials are breathable and waterproof, but the degree of waterproofness depends on the quality of the membrane and the outer fabric.
Water column testing - measuring waterproofness
When we measure waterproofness in a material we test how high a column of water can be before the water forces its way through the shell material. The degree of waterproofness is stated in the amount of millimeters the water column reaches before the water leaks through.
Picture a pipe that is 30 meters tall. The pipe’s bottom opening is covered with a shell material. Then you fill the pipe with water. When the water begins to leak through the material in the bottom we measure how high the water level is in the pipe. If the water reaches 20 meters in the pipe, the material has a water column of 20 000 mm. We’re essentially measuring how high of a water pressure the material can withstand.
Bergans use a water column of 5000 mm as the lower limit of waterproofness of garments. However, the waterproofness of a garment is also affected by how it is used. Because of this, our garments that have been designed for high activity levels in rougher terrains have higher water column measurements.
In reality, we don’t use large pipes anymore when testing the waterproofness of different materials. We use a special machine and follow a test procedure that complies with ISO-standards.
See how we test waterproofness:
As you can see, the principle of measuring the fabrics resistance to water is pretty simple. Now you know what “water column” means, and you can tell anybody who asks - that way we all become a little more knowledgeable.