Merino wool is a natural fiber grown by Merino sheep found mainly in the mountainous regions of New Zealand and Australia. This breed of sheep – Merino – originally came from the Atlas Mountains, subject to extreme weather conditions and temperature fluctuations ranging from -20 to +35 degrees Fahrenheit. As a result, the Merino grew unique coats that adapted to their environment – the source of merino wool.

Regular wool vs. merino wool

So, what is the difference between merino wool and regular wool?

The main difference between merino and regular wool lies in the thickness of their fibers. In general, traditional wool has average fiber sizes between 36 to 38 microns. On the other hand, Merino sheep’s unique coats have wool fibers with an average thickness ranging from 16.5 to 24 microns. Their wool is so thin that they are considered the finest wool in the world.

The fineness of merino wool also makes them much softer, lighter, and more breathable than regular wool. Also, the merino wool fibers are naturally highly crimped, meaning that they can trap body heat very effectively. And because merino wool is much finer than regular wool, there are many more fibers working to keep you warm, making merino the better insulating material. These properties of merino wool make it very desirable for clothing such as socks, shirts, or sweaters.

What makes merino wool warm?

Natural crimping in merino wool traps and retains body heat.

Crimping, or the natural waviness of wool fiber, is an essential factor in determining how much warmth the wool can provide. The natural folds and bends in wool act to trap air and allow the retention of body heat. Thus, the more crimped a wool is, the higher amount of insulation it can provide.

With coarser wool, there is less crimping because thicker fibers allow for less natural bending; this is not the case with merino wool. Merino wool has very fine fibers, making it naturally very highly crimped, even allowing for up to 40 crimps in one centimeter. This property of merino lets it efficiently trap air and help maximize retention of body heat. And because a thinner diameter allows for more fibers in an area, they can trap a larger volume of air and retain more heat than regular wool.

Furthermore, crimping also helps reduce the amount of heat dissipated from your skin. When the wool is wavier, there is reduced contact between the wool and your skin, meaning less heat is lost. The air trapped between the material and your skin also acts as a barrier, giving you a layer of protection from the elements and keeping out the cold.

Merino wool regulates body temperature and moisture, keeping you dry and warm.

Merino wool has an excellent ability to maintain your body temperature. It does this mainly by regulating the amount of moisture in contact with the wool, whether from sweat or external elements like rain.

Merino wool has the ability to absorb moisture, in the form of water vapor, of up to 35 percent or just over a third of its own weight. The absorbed water vapor is then stored within the fibers – which are also inherently porous – temporarily before being eventually released into the atmosphere. At the same time, its surface fibers repel water or moisture in liquid form, keeping your skin dry.

Therefore, when you sweat, merino wool wicks it away while it is still in vapor form so that you don’t feel any clamminess. This property can be very advantageous, especially in winter conditions, where sweat on your skin can get you cold and also feel unpleasant. Also, you don’t have to worry much if you suddenly get rained on, as merino can absorb a lot of moisture while still keeping your skin dry and warm.

Merino wool fibers can generate heat from the moisture they absorb.

Remember how merino wool can absorb plenty of moisture? Well, it turns out that this act of absorption can also produce heat and provide you with extra warmth.

When the wool absorbs moisture, molecules of the fibers collide with the water molecules in what is called an exothermic process, which results in the release of energy or heat. These molecules continue hitting each other until the wool can no longer hold water. This process can cause an increase in temperature of up to 10 degrees Celsius, depending on the fiber’s quality and absorption power.

So not only can merino wool absorb moisture, but it also has the remarkable property of actively generating heat while doing so.

The high breathability of merino wool allows for multiple layers of clothes.

It is important to layer your clothes when going out in winter conditions to ensure proper protection from the cold. But wearing several articles of clothing for warmth can cause you to sweat a lot and make you feel clammy, uncomfortable, and even cold instead. A significant reason why this occurs is because of the materials that comprise your layers.

You should have highly breathable layers that wick away sweat from your skin and let it pass through to other layers as well. Merino wool is an excellent material in this regard, as it allows moisture to escape even while it is still in vapor form, keeping you dry and warm. You can layer a couple of merino clothing before putting on something thicker while staying dry and not having to feel sweaty.

FAQs

Why is merino wool less itchy than regular wool?

Merino wool is less itchy than regular wool because its fibers are more delicate. Coarse fibers don’t bend when put against your skin, so they can cause prickliness or irritate your skin. With merino wool, however, the fibers readily bend and give you a feeling of softness instead.

Can you wear merino wool in warm weather?

Merino wool is very applicable to warm or hot weather. Because it is highly breathable, it allows sweat to escape from your skin quickly and keeps you cool and dry. This is especially so with thin materials such as Merino 150.

Conclusion

Merino wool is an excellent choice of material for providing you with insulation in cold weather conditions. The many properties of this material all work together to do so. So you can be confident that in whatever winter activity you plan on engaging in, you can count on merino to keep you warm and cozy.