It's soggy here in Cambridge!
Even when we are soaked through our merino base layers are still keeping us comfortable. Here's how.....
Wool is able to soak up to 30 percent of its own weight in moisture without feeling wet, hence it's ability to keep you warm even in the rain.The natural crimp of the fibres helps to wick moisture away from the body. Getting this moisture off your skin helps you feel warm and comfortable in wet conditions, but the complex make up of the fibres have still more ways of keeping you comfortable.The crimp in the wool fibre means that they trap tiny air pockets between them when they are next to each other. Air pockets act as insulators -- keeping you both warm and cool. Air can move heat by convection -- When air is contained in small pockets, it can't circulate easily, and the heat or cool is retained.
There's also some chemistry at work here. Wool fibres are made up of three layers. The first, keratin, is a moisture-loving protein that all animal hair has. It is designed to maintain a stable body temperature. Think how useful this is to babies, athletes and your own day-to-day living. The second layer is the cuticle a scaly covering. The overlapping scales are tiny, but as they rub against each other they push off the dirt. So it is self-cleaning, as anyone who's put their baby in wool knows. The third layer is a filmy skin the epicuticle which keeps the rain out. Wool is quite water-resistant, as duffel-coat wearers and sheep can testify. Now, the two outer layers have tiny pores which allow moisture to pass through to the keratin core, which absorbs it. The hydrogen bond of water, H2O, is broken, creating a chemical reaction within the fibre molecules to generate heat when it has taken on a lot of moisture. But because the air pockets allow moisture to evaporate from your skin, you won't overheat when you sweat.
So, you can see it's not just sheep who can enjoy being out in the rain in their woolly coats.
I'm not a fan of crackly waterproofs so when it's raining I prefer to wear the following for running/ walking in the rain. I'm not totally dry, but I feel warm and comfortable.
Wool base layers are also the perfect layer under a waterproof as they wick the sweat away from your body.
