For years I wore cotton t-shirts for all things outdoors, hiking, mountaineering, skiing, climbing, etc. It wasn’t until I joined the military that I realised I had been making my life more difficult and more uncomfortable than it should be.
So what is the point of a base layer?
The point of a base layer is to ensure efficient heat and sweat management. This results in safe and comfortable adventuring. They keep you cool by utilising breathable fabrics, dry through wicking and warm by trapping a layer of air next to the skin.
A quality base layer is essential to safe and comfortable adventuring. Once it has kept you warm and dry all day, you can enjoy the odour resistant properties and ease of washing.
In sudden or extreme weather conditions, it could even help to save your life by preventing you from getting hypothermia.
Find out the Best Base Layer for Hiking here.
Let’s delve briefly into the underworld of base layers to give you the confidence to know that you’ve got your clothing foundation.
What is a Base Layer?
It’s the layer of clothing you wear closest to your skin.
It usually lies beneath a mid-layer and an outer layer of clothing and can be tops, bottoms or all-in-ones. It’s part of a layering approach that makes controlling your body temperature easier and more effective.
Are Base Layers a 21st Century Gimmick?
Thermal underwear, vests, long johns, they’ve been around for a long time. In essence, they are all base layers and do a similar job to varying degrees.
When you are adventuring outside, facing the elements for extended periods, base layers have to adapt to the conditions you find yourself in.
The unpredictable and sometimes hostile environment of our planet means you need kit that will give you the best protection, in all situations.
Consequently, modern base layers have evolved from woolly vests that only offer protection in one environment. A decent, modern base layer will be fit for purpose from the dunes of the Sahara desert to the peaks of the Andes.
How Do Base Layers Work?
They trap air and regulate moisture, thereby regulating body temperature and as a result, heart rate too. They keep you warm in cold conditions and cool in warm conditions. They are breathable and so keep you from feeling clammy or sticky by wicking moisture away from your skin.
If your skin is dry, you’ll feel warmer. It’s the reason we feel colder stepping out of the shower than we did before going in.
How Should Base Layers Fit?
Like a second-skin!
To work effectively they should be in contact with your skin but not too tight they restrict movement. Don’t be tempted to buy a size too small, The last thing you want when you’re in search of freedom and fresh air is to find that your base layer is suffocating you around the neckline or hindering your freedom of movement around the arms or legs.
Base layers will come with some stretch, so ordering your exact size should mean that you will get a snug but flexible fit.
What Fabric Makes an Effective Base Layer?
A base layer can be made of many different fabrics but not all are as effective as each other.
Have you heard that natural fibres make for great base layers?
Well not necessarily!
Some natural fabrics like cotton might be effective at absorbing moisture from your body or the air but they aren’t any good at evaporating it. Consider cotton towels, they are fantastic at drying you, but they are excruciatingly slow to dry out especially on damp, cold days.
On the other hand, some natural fabrics like merino wool make excellent base layers. The fine fibres of merino create a layer that is not only super at wicking but great at evaporating moisture too so you will stay warm and dry.
Some modern synthetic fabrics are designed to work fantastically as a base layer too. When choosing a synthetic product, always look for fabric with a bit of stretch, good wicking and breathability. They should be high wicking and quick drying to be effective at their job.
Another aspect to bear in mind is the weight of the fabric used.
Do you need more than one Base Layer?
A single base layer is fine for a vast range of environments.
Buying a different base layer for every season is not necessary. A good all-rounder is the Arc’Teryx Phase Ar.
However, if you will be operating solely on the frozen wastes of the Arctic, for example, you may consider using a slightly thicker design.
Like good friend Olly, who wore the slightly thicker 100% Merino Wool Brass Monkeys base layer which served him well while chasing sea ice for Netflix series ‘Our Planet’.
Olly is on the left, he advocates 100% merino as a foundation. Building a layering system on top of this allows him to work most comfortably in extreme conditions. See some of Olly’s amazing photography here.
That said, always remember that layering is the key to keeping you at your optimum temperature An average weight base layer of about 150 to 200gms, combined with a number of other layers is a versatile approach for most.
Are Base Layers needed all Year Round?
A thin base layer in warmer weather is still a good idea. It will wick sweat away from your skin, leaving you feeling dry.
If it’s your only layer when the temperature rises you won’t be left with great big patches of sweat marks because it should be good enough to evaporate the moisture into the air.
Base layers are also perfect for when you are wearing another lighter layer on top, as it will stop wet patches showing on that too. So come rain or shine, a base layer is a good idea.
So the point of a base layer is?
It’s the starting point of staying warm, dry and comfortable despite what the weather and your activities might throw at you.
Natural or synthetic?
You decide, but it will be pointless if you don’t choose ones that wick and are breathable. Read more about this discussion here: Is Merino Wool Better than Synthetics?
Made up your mind? Check our guide to the Best Base Layer for Hiking.
If you have chosen well, it will be the first thing you put on and the last thing you take off.
See you on the mountain.