The Best Base Layer

Published December 19, 2018 | Updated November 08, 2020

In Search of The Perfect Base Layer

If you’re thinking about trekking to Machu Picchu, hiking the Coastal Path, or skiing in the Alps, what you are going to wear is an important consideration. And base layers are where it all starts. In this article, we take a look a what base layers are and why you should really consider alpaca wool for your next one, especially with the northern hemisphere ski season about to kick off.

What Is A Base Layer? 

A base layer is the first layer of clothing next to your skin. Traditionally, a base layer for the top half of the body would be a purpose-made undershirt or vest, that people would generally only wear under other clothing. But what a base layer top looks like has been changing with fashion, research and technology. More attention to styling and colour mean that base layers tops are now used as outer shirts, as much as they are used as undershirts. Most people don’t use base layers on their legs for everyday life, but these become essential during winter activities such as skiing, snowboarding and cold weather hill walking. See more about styles of base layers below.

Styles of Base Layer


The most basic type of base layer is a shirt-type garment, which could have short or long sleeves or be a vest top. These base layers tend to be relatively thin and quite lightweight. They can be used on their own in the summer, or as the first layer for cold or variable temperatures (where you start an activity cold but get hot later, for example).


Many base layers these days have features like quarter- or half-length zips, hoods and thumb-loops. This means they look more like jumpers, but are still made of thin enough fabric that you can wear them next to your skin. They are perfect for wearing on their own when exercising in cool weather, or under insulating layers for real cold.

Leggings / Tights

Because base layers need to fit snugly, options for your bottom half are most likely to be leggings/tights. Often known as “long johns” or “thermal underwear”, lower half base layers are usually designed to be worn under other clothing or as sleepwear for cold weather camping. Increasingly, some look good enough to be used on their own too.

red alpaca wool t-shirt base layer mens, long sleeve
indigo alpaca wool base layer womens, with hood
black alpaca wool base layer thermal leggings

What Does A Base Layer Do?

The principle function of a base layer is to wick sweat away from your body. This means that instead of soaking up the sweat, the fabric should have the ability to move the moisture from your skin to the other side of the garment, so it can evaporate with body heat. This is otherwise known as BREATHABILITY, which is one of the most important considerations when designing clothing for outdoor adventuresuse . If a fabric isn’t breathable, it gets wet with your sweat and can become clammy and cold. Some materials – particularly wools – maintain their insulating properties when wet, but some don’t (a key example is cotton) which can be very uncomfortable and even dangerous (in extreme circumstances), when you are out in the mountains. Whilst base layers should add some warmth to your layering system, their principle function is to wick sweat. It’s best not to choose a heavyweight fabric for your base layer, even for very cold weather, as thickness can become counter-productive in terms of breathability. It's best to leave the task of insulation to your mid layers.

What Materials Are Base Layers Made From?

Technical base layers need to be made from a breathable fabric, so no outdoor company worth its salt will market a cotton garment as a base layer. There are quite a few options out there these days, including bamboo viscose and silk, but the most common base layer materials are synthetics and wool.

    Synthetic base layers are usually made from polyester or polypropylene, which are both polymers derived from petroleum byproducts (including recycled plastics). Polypropylene is more breathable, dries more quickly and is a better insulator when wet than polyester. But polyester has a higher melting temperature so is easier to care for and is also more UV resistant. Synthetics are by far and away the lightest and most durable fibres, making them a very popular option for the outdoors. That said, more and more people are becoming conscious of the environmental impact of synthetics, so are looking for alternatives. It's also worth noting that synthetics are notorious for their odour retention, which makes them quite unpleasant after a day or two of heavy use.
    In the last 20 years, merino wool has become the gold standard for lightweight and breathable, natural fabrics. Finer than other sheeps' wools, merino wool is soft, unlikely to be itchy and is decent at wicking moisture. The structure of wool and its breathability means that it can also have a bit of a cooling effect when temperatures rise. And the best thing about it? Merino wool is odour resistant, so you can sweat in it for days on end without having to wear nose plugs! Merino wool isn’t very durable though, although new technologies that spin it with nylon go some way to solving that problem. It absorbs more moisture than synthetics, so isn't as quick drying, although does retain its insulating capacities when wet.
    The new kid on the block for outdoor clothing, very few companies use alpaca wool for technical garments or base layers, and those that do, often blend it with other fibres. Arms of Andes makes the only 100% royal alpaca wool base layers (as well as mid layers and underwear) on the market. But why? Merino is great, but it is significantly heavier than synthetics and far less durable. Alpaca wool has a similar structure to merino, but has a hidden feature – partial medullation – which means alpaca does everything merino does, but better! It is lighter than merino, but also warmer; and being more breathable, it is also more temperature regulating and odour resistant. Alpaca wool is considered hypoallergenic, as it isn’t coated in lanolin (or only tiny amounts). Furthermore, even though alpaca is softer on the skin than merino, it’s actually more durable. If all that doesn’t convince you, Peruvian alpaca wool is sustainably produced by small-scale alpaca herders, in the animal’s natural habitat. Arms of Andes is now using natural dyes and cotton to stitch together the garments, and produces all in one country (Peru), which reduces our overall environmental impact.
White alpacas and a brown llama in a field

Arms of Andes offers a complete range of performance clothing made from alpaca wool, starting with underwear, moving on to base layers and mid layers, topped of with accessories: socks, beanies and neck warmers. The superior properties of alpaca wool developed naturally, through thousands of years of exposure to the elements and harsh conditions of the Andes Mountains, making it the perfect fibre for outdoor use. 

Why use synthetics if nature already does it better?

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