It’s an irritating topic – you wander through the vastness of softshells and the more you familiarise yourself with all the technical stuff, the deeper you delve into the world of confusing details. Leading the pack – the membrane.
In the product descriptions, you always stumble upon terms such as Polartec, Apex, Windstopper, M1, etc. Even more confusing are values like MVTR, RET and hydrostatic head. Luckily, we’re going to shed some light on the dark maze of details.
g/m²/24h oder m²Pa/W? – Breathability
First, a little digression on a topic there’s no way around, even when it comes to softshell jackets – the breathability of the fabric. Breathability describes the ability of a fabric to allow moisture vapour to be transmitted from the inside to the outside of the jacket. Unfortunately, this is not at all easy to measure, as we have two different values:
The MVTR (Moisture Vapor Transmission Rate)
This is the measure of how much water vapour can pass through a square metre of a membrane within 24 hours. Accordingly, the rule is as follows: the greater the MVTR is, the higher the breathability. The best rate is approximately 40,000g/m²/24h – meaning 40,000g of moisture vapour per square metre per 24 hours. A membrane with an MVTR of 10,000g/m²/24h is considered to be very breathable. However, the problem with this is the sheer number of different methods for measuring the MVTR, namely around 30, which can in turn lead to different results. For example, the clothing company Patagonia had the breathability of its products tested by six different labs a few years ago and received a total of 6 different ratings.
The RET value
The RET (Resistance to Evaporating Heat Transfer) value determines the resistance that a material has to water vapour. In contrast to the MVTR, the lower the RET value is, the higher the breathability. This basically means that an RET value of 0-6 is very good, 6-13 good, and 13-20 satisfactory and anything less than 20 is unsatisfactory.
To be or not to be waterproof
What good is extreme breathability if more water permeates the inside than can be transmitted to the outside? Good news: almost all of today’s membranes provide sufficient protection. According to the European DIN EN 343:2010-05 (Protective clothing – Protection against rain), a product with a hydrostatic head of over 800mm is “waterproof (Class 2)” and over 1300mm “waterproof (Class 3)”. However, in heavy rains or when sitting on a wet surface, neither is sufficient. That’s why most manufacturers offer fabrics with a higher hydrostatic head of up to 20,000mm.
The membrane – windproof or waterproof?
Yet another stumbling block in our way: there are two kinds of softshell membranes: the first keeps the wind out and protects your body from overcooling, whilst the other protects you in wet conditions. Here’s a brief overview:
Many manufacturers, such as Arc’teryx rely upon Gore softshell membranes, which reliably keep wind and water out of the jacket’s interior and have good breathability (RET <13). In addition, there are other membranes, some of which developed by the clothing companies themselves, that work just as well as the market leaders:
- Mammut DRYtech
- Marmot M1
- The North Face Apex WeatherBlock
- Polartec Powershield Pro
The true purpose of this membrane is to block winds in order to avoid the wind chill effect. In terms of waterproofness, the border between waterproof and water-repellent becomes a little blurry. Windproof membranes can withstand rain longer than a softshell jacket with a waterproof laminate. But, if you happen to run into a monsoon, all bets are off. Windproof membranes include:
- Gore Windstopper
- The North Face Apex ClimateBlock
- Marmot M2
The days when we distinguished between a waterproof jacket and a softshell are long gone, but there is some good news: You no longer need to sacrifice the comfort of a softshell when it rains! The bad news? Well, deciding just got that much more difficult!
If you have any questions, feel free to ask our experts in customer service. They are available during the week from 9 a.m. till 4 p.m. and can be reached by phone at 03 33 33 67058 or via e-mail.
There’s a lot going on in the climbing and outdoor industry. New products are being invented, existing ones are being reworked and improved, and we, too, are learning more every day. And, of course, we would like to share this knowledge with our customers. That’s why we regularly revise the articles at base camp. So, don’t be surprised if a post changes a bit in the coming months. This article was last edited on 26/10/2015.