Merino Wool - Properties of the functional, natural fiber

Merino wool is THE favorite fabric from sport- and outdoor enthusiasts. The natural fiber is soft; breathable; doesn’t smell, even after multiple uses; warms in cool temperatures; and cools in warm temperatures. So, where do all these great properties come from? Keep reading to learn more about the Merino Wonder Fiber.


To produce the Merino wool end product, high-quality virgin wool from the Merino sheep is used. The hair of a Merino sheep’s coat is made up of light, thin hairs which are durable enough to handle extreme temperature changes.


In contrast to normal sheep’s wool, Merino wool’s fibers are much finer—in fact, they’re only half as thick. The Merino fibers measure between 15.5 and 24 micrometers (i.e. 1/1,000 of a millimeter.) In comparison: human hair is around 30 micrometers thick.

difference human wool merino wool

Fabrics feel itchy on our skin when they’re made up of thicker, less-flexible fibers. Our human threshold for feeling that a fiber is “itchy” is about 25 micrometers—that’s why normal wool feels itchy, where Merino wool feels comfortable and soft.


Sheep’s wool—and especially Merino wool—both hold a number of wonderful, natural properties. Merino wool:

  • Isn’t itchy
  • Is breathable
  • Is temperature-regulating, which means it keeps you cool in the summer and warm in the winter
  • Repels unpleasant odors
  • Keeps your skin hydrated, without feeling damp
  • Keeps you warm, even when the wool itself is damp
  • Wicks moisture away from the skin
  • Doesn’t wrinkle
  • Is very flame retardant
  • Doesn’t produce static
  • Is naturally UV-protectant
  • Is bio degradable
  • Is a renewable, sustainable fiber


It’s thanks to the form and structure of Merino wool’s fibers that these properties exist. Since the fibers are naturally crimped in shape, the fibers lay closely together and create small air chambers. These air chambers are what keep your body warm. The fibers’ composition results in an insulating and temperature-regulating effect: since air is a poor heat conductor, the heat isn’t able to pass through the air pockets, and stays near your body.


Yes! Merino wool products are also ideal for hot days. Merino wool is capable of holding up to 33% of its own weight in moisture. The moisture is then held within the fibers, which means that the fibers’ surfaces remain dry. That’s why—and how—things like sweat or rain are kept away from the skin itself, and are instead held within the fibers. Plus, warm summer air helps the moisture that’s been wicked away from the skin to then evaporate. That’s where Merino wool’s cooling effect comes from when it’s used in warm weather—when the water evaporates, it leaves your skin feeling cool. The most important thing to keep an eye on when choosing a piece of Merino wool clothing: make sure that the textile has a high wool percentage. The higher the wool content, the better it will be at wicking moisture.


Did you know that sweat is actually odor-less? Unpleasant sweat-related odors start when bacteria begins to break down the sweat. Artificial fibers have a very flat structure, in which sweat and bacteria can easily implant themselves. In contrast, Merino wool has a scaly surface, which makes it nearly impossible for bacteria to embed itself. Plus, Merino wool has a self-cleaning effect. Merino wool fibers are made of two different types of cells, which constantly rub against each other. Through the constant rubbing process, the fibers are very effective at cleaning themselves.


The majority of Merino sheep live in Australia, New Zealand, South America and South Africa. The sheep can be shorn a maximum of twice a year. In sourcing the wool, animal rights and protection must also be respected and looked out for. In particular, Merino sheep in Australian farms often undergo the painful Mulesing process. This process, which involves removing the skin from the sheep’s rear, is still sometimes used in Australia to prevent disease-carrying flies from laying their eggs.

properties mulesingfree merino wool

When purchasing Merino wool products, it’s important to check the source of the wool. A low price is often the result of the wool’s source; a product made of mulesing-free Merino wool is often more expensive. But when you buy items that use mulesing-free sourced Merino wool, you’ll get to enjoy a high-quality product—without a guilty conscience.

For us at Giesswein, animal protection is a very important topic. That’s why we source our high-quality, mulesing-free Merino wool from farms in Uruguay. In addition, we ensure that our sources hold high standards in caring for the animals; these standards are continually audited by our vendors.

Read more in our post: No to Mulesing


At Giesswein, our high-quality products begin with the choice of our materials. For our Merino wool products, our mulesing-free yarn is double-plied. This makes our fabrics sturdier—and last longer. Depending on the product in which the yarn will be used, the fabrics are then knitted and refined differently:

  • During our Giesswein-developed 3D-Knit technique, the resulting fabric has a unique stretch effect. The textile is both flexible and robust—perfect for a shoe that offers exceptional comfort.
  • Our special hemming machine makes the fabrics even softer.
  • When it comes to our boiled wool fabrics, the wool fibers are turned into felt; this results in small air chambers throughout the textile, which work as insulation.

Through these special production processes, we further strengthen the natural properties of Merino wool—which results in unique, high-quality products.

We've made it our mission to reinvent the basic properties of wool in order to create one-of-a-kind products.

Markus Giesswein


For a better overview we have summarized all information about merino wool in an infographic:

Merino Wool Infographic

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