Whether hiking, trekking or skiing, merino wool has established itself as a reference for outdoor activities. It offers unmatched comfort compared to synthetic fibres. But what makes it so special, and how do you choose the right one? Cimalp reveals everything you need to know about merino wool.
The origins of merino wool
The emergence of merino wool
The history of merino wool dates back to the 12th century, when sheep from Asia Minor were introduced to Spain. For several centuries, it remained an exclusive product of the country, and its wool was considered the finest in the world. In the 19th century, merino sheep were finally exported to other regions with more favourable climates.
Current production
Today, merino sheep farming takes place primarily in Australia, which accounts for around 80% of global production, in New Zealand and South Africa. They can, however, be found worldwide, including in France.
For several years now, animal welfare has been a central concern. Mulesing, a painful practice used to prevent parasitic infestations in sheep, has come under fire. A growing number of producers now guarantee mulesing-free farming.
Merino wool is considered one of the finest natural fibres for outdoor clothing. Its fineness is exceptional, ranging from 17 to 24 microns, compared to over 30 for standard wool. The quality of the fibres and ethical production mean that its cost is, however, higher than synthetic materials.
The properties of merino wool
Thermoregulation and natural insulation
Like any natural fibre, merino wool has its advantages and disadvantages. First, it has thermoregulation properties. The fibres trap air and create natural insulation. Garments retain heat in the cold while remaining breathable in the heat.
Thanks to its unique properties, you can head outdoors in summer or winter alike, without suffering from temperature fluctuations. Merino wool garments can be worn all year round, particularly during mountain activities where the weather can change rapidly.
Moisture and odour management
Merino wool is also renowned for its antibacterial properties. The keratin structure of the fibre naturally limits bacterial growth, which is responsible for unpleasant odours. Merino wool garments don't need to be washed as frequently as those made from synthetic fibres.
On top of its odour-resistant properties, it offers good moisture management. It can absorb up to 30% of its weight in water without feeling wet. The dry sensation persists even during prolonged effort. It does, however, reach its limits in very wet conditions. Synthetic fibres such as polyester are more hydrophobic in those situations.
Comfort, softness and freedom of movement
The word "wool" often puts people with sensitive skin on edge. Contrary to popular belief, merino wool doesn't itch. The fineness of its fibre instead delivers unparalleled softness.
The fabric is also stretchy and moves with you. It is also wrinkle-resistant. Even after being folded or rolled up, it returns to its original shape — a real bonus when packing minimalist rucksacks.
Lightweight, durable and easy to care for
Merino wool also stands out for its lightweight nature. The fine fibres allow you to wear soft, airy garments in any season. Despite their fineness, they remain surprisingly resilient. The finest models do, however, wear faster than synthetic fabrics, particularly at friction points.
Caring for merino wool is relatively straightforward. Modern garments are generally treated with a "superwash" finish and are machine washable. However, avoid harsh detergents, which damage natural fibres, and steer clear of the tumble dryer. Instead, opt for a gentle cycle and air dry.
A natural, eco-friendly and protective fibre
Merino wool is 100% natural and renewable. Its environmental impact is limited, especially when it comes from farms that respect animal welfare. It is biodegradable and can even serve as fertiliser, releasing nutrients into the soil.
Finally, merino is a natural flame retardant. This means it doesn't melt, doesn't stick to the skin and self-extinguishes in the event of fire. This property makes it a highly valued material for bivvy camping and expeditions where technical garments are worn close to the body.
Which activities are best suited to merino wool?
Winter activities
One of the main strengths of merino wool is its adaptability to almost every outdoor discipline, all year round. Fans of winter hiking or high-altitude trekking particularly appreciate it, as it retains warmth even when damp.
In skiing, ski touring or snowshoeing, merino wool provides consistent thermal regulation. You don't overheat on the ascent and you don't suffer from the cold on the descent. Its moisture management also prevents that post-effort chill.
In mountaineering, merino wool is often used as a base layer, worn beneath technical layers. It creates effective natural insulation without adding weight to your kit.
Mid-season activities
In mid-season, merino wool brings adaptability and climatic comfort. In autumn and spring, temperature variations are frequent. It is therefore highly practical for Nordic walking, light trail running or fast-hiking, as it remains breathable during effort and insulating at rest.
In climbing, via ferrata or other mountain activities, merino wool ensures excellent freedom of movement. It delivers natural suppleness and elasticity for those who wear it.
Summer activities
In summer, heat regulation and moisture management are key. Contrary to what you might expect, merino wool is not overly insulating during summer hiking or trekking in warm weather. It draws heat and perspiration away from the body and even offers UV protection.
It is also highly practical for bivvy camping, bikepacking or travelling, as it is lightweight and takes up very little space. In this case, its main advantage remains the fact that it can be worn for several days without washing, thanks to its odour-resistant properties.
Finally, merino wool is also used in trail running or mountain racing. Its excellent body temperature management makes it the ideal choice for long outings.
Choosing the right merino wool clothing
Weight
The choice of merino wool clothing depends on its intended use and weather conditions. The weight or fabric density, expressed in g/m², determines the warmth and thickness of the garment.
The higher the weight, the warmer and more insulating the fabric:
- 150 g/m² or less: lightweight and breathable fabric, ideal for intense activities in warm weather.
- 150 to 200 g/m²: versatile use, perfect for mid-season activities.
- Over 200 g/m²: thick fabric, used as a thermal base layer for winter activities.
For versatile outdoor use, we recommend a weight of around 180 to 200 g/m².
Composition
When purchasing your merino wool clothing, you can choose between 100% merino or a blend with synthetic materials such as nylon, polyester or elastane.
100% merino has the advantage of being ultra-soft, offering maximum breathability and being naturally odour-resistant. It is, however, less resistant to abrasion and dries a little more slowly. It makes an excellent base layer, worn directly against the skin.
A blend of merino and synthetic fibres combines the advantages of both materials. The garment offers better durability and resistance, dries quickly, and is lighter and more elastic. It does, however, lose some of the natural purity of merino. It is recommended for more demanding sports, intensive or repeated use.
Type of garment
The type of garment helps you choose each layer of your outfit. Merino wool thermal underwear is sought after for its warmth without overheating and its lasting comfort. Long-sleeved tops and tights are therefore ideal for making the most of winter activities.
Merino wool T-shirts can be worn throughout the year. To choose the right one, go for a fitted but not tight cut, and a light to medium weight depending on the weather.
Mid-layers (merino jumpers, jackets or hoodies) can be worn over a t-shirt or as a base layer and offer excellent natural insulation. Opt for a higher weight and a blend with synthetic fibres for added durability.
Accessories such as merino wool socks are also highly practical. They keep feet dry and odour-free. Again, blends with nylon or elastane are recommended for greater durability.
Merino wool combines technical performance, comfort and environmental responsibility. When buying, choose garments from ethical farms that suit your activity. You'll enjoy durable comfort in any season.
