A friend of a friend of Outdoor Look recently asked: “So, this baselayer thing… What exactly is it? And why do so many people wear them? And do I really need one?” The poor man had spent too many years to count wearing a cotton t-shirt under his fleece while hiking the English countryside.

So we thought we would bring you a guide to the benefits of the baselayer. And why you might need one.

A baselayer comes in a range of forms and 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.

So a baselayer works by keeping your body heat in but allowing sweat out so that you do not become uncomfortably damp (unlike if you wear a cotton t-shirt as a baselayer!).

The advantage of layering your baselayers

Instead of putting on just one or two thick layers to keep your body warm, most outdoorsy folk now use a system of layering. This sees them wearing many thin layers, each of which trap in essential heat.

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’re a bit chilly because you have just started out. So you wear a couple of baselayers and a waterproof jacket outerlayer.

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.

What is this magical baselayer material?

Effective baselayers are NOT made from cotton. Cotton gets sweaty, wet or damp and then ends up feels uncomfortable and cold against your skin. Effective baselayers are made of a range of different materials that keep you warm and let the sweat wick away, so that you stay warm And DRY. Magical materials include, 100% polyester, a polyester/elastine mix, polypropylene and Merino wool.

Most baselayers feel smooth against the skin and they are very lightweight. 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 also have a range of baselayer warmths to suit different seasons and activities. For example, the Trespass technical baselayer range comes in three performance levels. We will be testing a new Trespass Active baselayer TP 75 soon.

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 in the winter.