Properties of sheep's wool

  • Properties of sheep's wool

The tried and tested properties of sheep’s wool and merino wool have been proving their worth for centuries. Even today, their functionality is virtually unparalleled in the world of textiles. Mountaineers in particular are often exposed to extreme conditions at different times of the year, so they need clothing that provides protection and functions reliably in all situations. Merino wool offers numerous advantages: It provides good insulation, transports moisture and has anti-static properties; it doesn’t itch, smell or crease much; it is lightweight and keeps its shape. And it does all this in a completely natural and sustainable way.



Nobody wants to smell. Wool has an antibacterial effect, so you can get by with just a few items of clothing, even on mountain hikes lasting several days. This is down to the structure of the wool fibers: Their surface is reminiscent of roof tiles (compared to synthetic fibers, which are smooth), so it is difficult for bacteria to get lodged inside. These bacteria are responsible for that stuffy smell.
Furthermore, moisture is absorbed directly into the fibers of merino wool, allowing less sweat to build up on the skin. Wool fibers also virtually have their own in-built washing machine: The keratin – the protein molecules in the merino fibers – simply breaks down the odor-forming bacteria, so we can enjoy the benefits of this unbeatable self-cleaning function and don’t have to wash our merino wool clothing as often. When you come back from a mountain tour simply leave your product to air, preferably in humid or damp weather. You will then be able to wear it again the next day and it won’t smell. Your companions and the environment will thank you for it!



Wool fibers are hydrophilic fibers – and that’s precisely what makes them so extremely functional. They provide incredible warmth and can absorb up to 35% of their own weight in moisture without feeling wet to the touch. The fiber surface remains dry, while the moisture moves to the fiber core. In contrast to down or polyester, wool thus feels warm and comfortable, even when wet. Furthermore, it doesn’t suppress the body’s natural cooling function of sweating. Merino wool is also breathable: The scientific term for “breathability” is moisture buffering. Moisture buffering refers to the fibers’ ability to absorb moisture from the microclimate directly through the skin and release it again when the moisture level drops – i.e. when it is drier again.
This is why wool dries out quickly, too – even keeping you refreshingly cool in the hot summer months. And of course, it also releases moisture, which in turn provides a feeling of freshness in warmer temperatures: warm ambient air leads to a quick drying effect, which produces a refreshing evaporative coolness. This is exactly why we use merino wool to make the extremely functional and quick-drying underwear that we all love so much.



Wool fibers are true all-rounders that do exactly what you expect from them, whatever the season – they cool you down in summer, and warm you in winter. Even our grandmothers knew that wool keeps us warm in winter – that’s why we all had those wonderfully itchy woolen jumpers.
But keeping us cool in summer? Even our grandmothers wouldn’t have thought of that. The thermo-regulating properties are based on two principles: Firstly, wool fibers have a naturally rippled structure which allows body heat to be stored in air chambers, thus facilitating optimum insulation in woolen fabrics. This is also what makes merino wool products such effective layers according to the onion principle. The air serves as an insulating layer against heat and cold in both summer and winter. This insulating layer also enables merino sheep to survive the Tasmanian summer, when it can get very hot. The second principle is based on cooling by evaporative coolness. Wool can absorb more than 35% of its own weight in moisture (without feeling wet to the touch). If the ambient air is warm, the moisture dries faster, resulting in this refreshing evaporative coolness. If our grandmothers had known this, perhaps woolen T-shirts would have existed in the old days.



Merino wool does not itch! At 16,5–19,5 microns (one micron = one-thousandth of a millimeter), the fine wool fibers are so thin that they are well below the human itching threshold of 25 microns. Because the fibers are so soft, they bend when they come into contact with the skin without creating an unpleasant sensation. And if you are one of those people who still believes that wool itches (because you are constantly reminded of the woolen jumpers your grandma used to knit), we have developed special versions (such as MERINO SUPERSOFT and MERINO COMPETITION) that are sure to change your mind. In these combinations, other types of fibers come into contact with the skin (Lenzing Modal made from beech wood cellulose – MERINO SUPERSOFT) or we have mixed in a small amount of synthetic fibers (MERINO COMPETITION).



Even though wool has an inherent odor-neutralizing effect, you might find yourself in a situation where someone squirts ketchup on your product and you have no choice but to wash it. But don’t worry, it’s easier than you might think: We use the “Total Easy Care” process to give our merino wool a special finish that allows you to machine wash it at 30 or 40°C. Only the scaly surface structure of the wool fibers is washed, thus protecting the wool from severe shrinkage.  



Wool also supports the concept of sustainability and is naturally 100% ecological! Depending on their breed, merino sheep are shorn once to twice a year – so they automatically grow a new coat. All that is needed for these natural fibers to grow is water, fresh air, sun and tasty grass. All pretty basic stuff.
The shearing process is purely manual labor and causes the animal absolutely no pain. And who wants to haul a thick fleece around with them on a hot summer’s day anyway?

What’s more, wool is also biodegradable and offers all sorts of functional benefits without any chemical additives. The fibers themselves contain the technology that is so very important for mountain sports, so the hard work has already been done. By the way, a wool fiber can be bent up to 20,000 times without breaking. Fabrics made from wool are thus remarkably durable. This also helps to prevent unnecessary waste. The fact that woolen products do not have to be washed so frequently thanks to their self-cleaning function also has a positive impact on the environment.



Although Australia and Tasmania are particularly exposed to harmful UV radiation due to a hole in the ozone layer, not once has a sheep suffered from sunburn. Why is that? It’s because of their wool, of course – it simply absorbs some of the UV radiation and keeps it away from the skin.

To fully understand how this works, you have to know what UPF (Ultraviolet Protection Factor) means. The abbreviation looks a bit like a term you might recognize from your sun cream (SPF = Sun Protection Factor). The similarity is no coincidence, because UPF is a value that indicates how much UV radiation is blocked. Here are a couple of examples: A T-shirt with UPF 10 (the average for a white cotton T-shirt) allows ten percent of UV radiation to pass through to the skin. Factor 15 is the minimum value required to comply with the Australian standard for basic protection. UPF 40 indicates excellent protection, blocking 97.5 to 97.6% of all UV radiation from the skin.

When we apply these values to the most common textiles, we see three groups emerging: Polyester has the highest integrated UPF, followed by wool, polyamide and silk. Cotton, viscose and linen have the lowest level of protection.

But other factors also influence the UPF, such as the construction of the material, the color (dark colors provide more protection than light ones, with bright red and green providing the best protection of all) or the fit (whether the shirt is a close or a loose fit). The condition of the product also plays a role, as the UPF decreases considerably when the fabric is wet. When choosing a new ORTOVOX product, you should also make sure you choose the right fit and color if you want to get the best possible protection against UV radiation. ORTOVOX shirts, for example, have a UPF of between 20 and 50+ depending on the density of the fabric and the color.

Did you know?

The features of merino wool compared to other alternatives on the market

Today, there is a variety of products, materials and fibers for every mountain sport activity, and they all have their individual advantages. We have provided an overview to show you what you should be looking for when making your selection:
Did you know?


A 100% natural fiber, merino wool has several highly functional features. Of these, some of the most important are that it doesn’t stink when you sweat and that it still warms you when it’s wet. Only the finest merino wool, which doesn’t itch, is used for t-shirts, underwear, etc. For this reason, products made from merino wool are slightly more expensive than the alternatives, but they often last longer.

Even when wool is wet from sweat, it still warms you. This is thanks to an exothermic process: The proteins in the fibers warm up as soon as they become wet.

Temperature management:
Wool is comfortable at a broad range of temperatures and does not feel stuffy, even when it’s really warm. This is thanks to small air chambers between the crimped wool fibers.

Wool can absorb up to 35% of its own weight in moisture without feeling wet to the touch. The body’s natural method of cooling itself with sweat is not hampered by the wool.

Merino wool has an anti-bacterial effect because the surface of the fiber is scaled. This means that it is difficult for nasty odors to form.

Merino wool makes use of natural resources, regrows regularly and does not require any ingredients other than water, fresh air, sun and grass. It is also up to 100% biodegradable and does not require any chemicals.

A multi-functional and sustainable alternative to synthetics. A bit more expensive but longer-lasting and, above all, less likely to emit odor – so you need fewer changes of clothes on long tours.



Products made from the synthetic fibers polyamide or polyester are often cheap(er), soft, robust and quick drying. Some manufacturers are already using recycled polyester.

Synthetic fibers do not absorb moisture. However, certain features of the yarn ensure that sweat is quickly wicked away from the body.

Temperature management:
It depends upon whether the product is designed to be breathable or to retain heat.

Synthetic fibers do not absorb moisture, but wick it away towards the outside where it quickly evaporates. This means the body does not feel as if it is sweating.

Synthetic fibers are smooth, which means bacteria are able to hang around for longer and create nasty odors.

Because the fibers are synthetic, chemical processes are required to “construct” them. This creates particularly functional yarns. Some companies are increasingly using recycled materials to make new products.

Synthetic fibers are very soft and fine, which means that people with sensitive skin in particular prefer these products. The products are very tear-resistant and quick drying. However, the advantages and disadvantages must be weighed up and depend upon the area of use. 



Cotton is extremely skin-friendly, long-lasting and tough – even multiple washes do not affect the fibers.

Unfortunately, cotton becomes saturated with moisture relatively quickly when you sweat. It also takes longer for a cotton t-shirt to dry compared to other materials.

When dry, cotton very quickly reaches the same temperature as the skin. However, if it becomes wet due to sweat or rain, it quickly becomes saturated with moisture, cools down and becomes heavy.

At some point, cotton will start to smell, particularly under the armpits. When this happens, washing often no longer helps because bacteria have taken root in the material. These break down the sweat and discharge foul-smelling secretions.

When wet, cotton is even more tear-resistant than when dry. It is also extremely flexible and flame retardant.

The guidelines of organic farming are adhered to in the production of organic cotton in particular. This means that the use of chemical pesticides, insecticides and chemical fertilizers is taboo.

The wear comfort is (almost) unbeatable. But as soon as you start to move and sweat a lot, cotton is not functional enough and is, for example, not breathable.

  • Stefan Krause, Head of Product at ORTOVOX

The benefits of wool are obvious.

"But other materials are better at protecting against rain, snow and wind. That’s why we combine the positive features of wool with the durability of other materials, such as synthetic fibers. 
To create the perfect microclimate, we put the wool on the inside against the body and use more robust fibers where necessary on the outside, where they can protect against wind and weather."