What is a baselayer? It’s a good question and one that many people ask when they start to think about the right kit for wearing while enjoying the great outdoors. A baselayer comes in different shapes:

  • A top: Short-sleeved or long-sleeved, with a crew neck, quarter zip or all varieties of zip
  • Leggings: Long, three-quarter or shorts
  • Vests and pants, ie underwear.

The idea of a baselayer is that it is worn against the skin and keeps you warm. They are made from a “magical” material that keeps you warm but also allows sweat to wick away to the outside. Most fabrics are either man-made 100% polyester, a polyester/elastine mix, polypropylene or natural Merino wool.

How does a baselayer work?

A baselayer is like another layer of skin, which keep your body temperature even. One base layer is enough for many conditions but if you’re looking for extra warmth then two base layers will help to trap more heat and keep you warmer. But a baselayer has another advantage; it allows sweat to evaporate through the material. This means that you’ll stay warm and dry.

What about cotton as a baselayer?

While a cotton fabric layer might keep you warm for a while, as soon as you start to sweat it simply holds the water vapour and will eventually become wet. Once the cotton layer is wet, you’ll feel damp – and end up more than miserable, especially if you stop exercising, when the cotton layer will make you cold and damp.

The advantage of layering your baselayers

Instead of putting on just one or two thick layers to keep your body warm, most outdoors people know the benefits of a system of layering. This sees them wearing many thin layers, each of which trap in essential heat between the layers.

By wearing many layers it is possible to add more or peel off some as you become warmer of cooler and according to the conditions.

So, for example, you’re climbing a hill or cycling for a few hours. To start with you might feel a little chilly because you have just started out. So you wear a couple of baselayers and a waterproof jacket outer layer.

As you start to climb or cycle further and harder your core body temperature rises and so you peel off the outer layer and also one of the thinner base layers. Because base layers are made of “magical” material the sweat created by your extra effort is allowed to escape to the outside of the baselayer material and so you remain warm but without becoming damp.

Then, at higher altitude, the wind picks up and you begin to feel a bit chilly again so you put your second base layer back on, adding another layer of warmth.

Baselayers in the summer

A t-shirt or lightweight long-sleeved baselayer is a great asset in summer, too. This is when you’re much more likely to sweat and a good baselayer will allow your sweat to effectively wick away so that your skin remains cool and dry.

The modern baselayer – and fit

Most baselayers feel smooth against the skin and they are very lightweight. It's up to you whether you wear it skin-tight or a little looser, but for best effect, a baselayer should fit snugly. There are baselayers to suit male physiques and more tailored baselayers for women. If you feel self-conscious, buy a tightfitting baselayer and add a looser fit t-shirt over the top.

These days they come in lots of different colours and designs and can look as good as a top for wearing to the pub as they are effective for heading out for a range of outdoor pursuits.

Other benefits of baselayers

Most baselayers are also quick drying and many come with an antibacterial finish (to stop them whiffing after a few wears!)

Many baselayer brands have a range of baselayer warmths to suit different seasons and activities. For example, the Trespass technical baselayer range comes in three performance levels. Check out a review of the Trespass Active baselayer TP 75.

What are baselayers good for?

Whatever your chosen outdoors pursuits you’ll use a baselayer or two or three. They are great for walking, cycling skiing, running, snowboarding, horse riding, playing football and pretty much any form of exercise, except swimming.

It’s hard to imagine a 21st century outdoors wardrobe without a drawer full of baselayers.