The Science Behind Merino Wool

As winter approaches, you'll probably be hearing the words "merino wool" thrown out a lot, especially in performance product. It may sound like a marketing ploy but believe us, it lives up to the hype. So how does it differ from plain 'ole wool? Let us explain.

What is Merino Wool?

For years, brands such as Smartwool and Icebreaker have been crushing their competition because of the high quality wool they have been using in their products. To explain how exactly merino wool work and its benefits, we have to explain what exactly merino wool is, first.

The merino is one of the world’s most ancient breeds of sheep. And one of the toughest. The breed origins are from Spain, but the modern Merino was domesticated in Australia, where Icebreaker's HQ is located. Where regular sheep would freeze to death, the merino's fleece is built for extremes. Breathable in summer, insulation in winter, yet still soft and exceptionally lightweight.

The Benefits of Merino Wool

The benefits of merino wool over normal wool are endless. We'll explain the science behind the claims, stay with us.  

  • Breathability and Moisture Management

  • Natural Heating and Cooling

  • Wicking Wonders

  • Strength and Resilience

  • Odor Resistance

  • Ditch the Itch

  • Quick Drying

  • Natural Sun Protection

 The Science


According to Smartwool, breathability is the ability of a fabric or fiber to transport moisture in the vapor state from an area of higher humidity to an area of lower humidity. In other words, the more breathable a product is the better it is at removing moisture from the microclimate (the space between your skin and the garment). As your body heats up, the moisture vapors will be absorbed by the wool fiber, and released to the drier environment outside of the fabric; releasing heat and keeping the wearer dry and comfortable.

A Merino fiber can absorb and retain up to 30% of its own weight in moisture and still feel dry to the touch.

Heating & Cooling

Wool often is credited only being good in the cold. You can thank all the wool sweaters and scarves you wear during the Chicago winter, but wool truly is a four season fiber.


In cold weather, Icebreaker claims its merino performance fabric uses moisture absorbed from the environment to generate heat (a process called “heat of sorption”). Its crimped (wavy) fibers also contain millions of air pockets that lock in body heat to keep you toasty. Smartwool's website even claims that merino fibers and fabrics can absorb up to 30% of their dry weight before feeling wet. Most synthetics feel wet after they absorb less than 7%. Take a look at how Icebreaker's tech works below.


In warm weather, Icebreaker merino keeps your skin cool by transporting moisture vapor away from the skin to be evaporated. And because Icebreaker merino breathes beautifully, moisture vapor escapes without making you feel clammy.

Moisture Wicking

Merino pulls moisture vapor to the surface of the fabric, where it is able to evaporate before the vapor turns into sweat. Icebreaker's website claims it can absorb up to 30% of its own weight in moisture before you even start to feel wet, and it dries fast. 


Image by Smartwool

Merino wool is predominately made of interlocking protein molecules known as keratin, the same protein that is in our own skin and hair! Individual wool fibers have the ability to be bent, flexed and stretched in any direction 30,000 times or more without damage. In addition, wool fibers have a natural curl called the “fiber crimp” which improves the elasticity and over all resilience of the fiber.


As mentioned previously, wool’s ability to effectively manage moisture helps eliminate odor-causing bacteria because it doesn't give the bacteria the moist environment they need to thrive. 


Most people associate wool with “itchiness”. This is because of the diameter of the fibers used. Merino wool is able to stay itch-free thanks to its fiber’s smaller diameter, or being “finer”. These fibers are more flexible and softly bend when pressed against the skin and, therefore, don’t itch like other wool.

For more information on the benefits of merino wool, visit Smartwool's website or Icebreaker's website.

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