• FR3ND

Merino wool shirts – What’s the hype? How does it outperform cotton and polyester?


Merino wool isn’t a new technology. It’s been used in garments for centuries but started to get replaced within sportswear with synthetic fibres as they were cheaper to produce and shared some (not all) of the performance benefits that merino wool offered.

Merino is now becoming much more popular as the world wakes up to the environmental damage caused by producing clothing made from synthetic fibres, not only in the way they are produced but also the lifetime of the product, including how they degrade after use in landfills.

Before we get into the eco benefits of wearing merino wool, here are some of the key performance benefits of wearing a merino wool shirt over say a traditional cotton shirt or even a blended cotton and synthetic mix.

Merino wool is hydrophobic, meaning it doesn’t like to have moisture on the surface of its fibre and therefore repels it from the outside. However, the inside of the merino fibre absorbs vapour (body heat) and this helps the fabric breath and keep the wearer comfortable. For example, let’s say you’re running late for a meeting and start to run or walk at a fast pace, your body warms up and wants to sweat to keep you cool. As the body warms, it emits moisture vapour that gets absorbed by the merino fibres as it grabs it from the skin. It then gets pulled to the outside of the merino garments to release it to the macro environment. It’s constantly sucking moisture vapour away from the body and releasing it, keeping the wearer more comfortable than say if they were wearing a synthetic fibre or cotton.

If you were wearing a cotton shirt in the same scenario, the cotton fibre is hydrophilic, the exact opposite of merino wools hydrophobic properties, soaking up sweat like a sponge. The issue comes from the poor performance for cotton to dry and this is why cotton shirts take so long to dry, leaving the shirt damp, meaning you arrive at your meeting with sweat marks that take an age to disappear. This sweat also causes the body to chill as the wind or air conditioning cools the moisture, making the wearer feel cold.

Polyester performs in a different way al together. It is man-made and therefore can be engineered to be hydrophobic or hydrophilic. The main difference is polyester doesn’t absorb moisture vapour and therefore the heat generated by you walking faster or running turns to sweat faster. The polyester then absorbs this sweat but also absorbs the body odour too as it loves bacteria, unlike merino wool.

Many consumers believe Merino wool isn’t suitable for warm climates and think of it as a baselayer or thermal fabric to be worn to help keep you warm. They are only half correct as it will keep you warm when it’s cold or you feel cold, however it regulates temperature and therefore cools you in hot conditions. This sounds like magic, however the science backs this up as the process of taking moisture off the skin and then releasing it to the atmosphere through evaporation is a cooling function. Its why we sweat when we get warm, to cool the body and allow the moisture to evaporate. If you take this logic one step further, think about Australian merino sheep that have to endure souring temperatures of +45˚ while wearing a huge thick fleece. The sheep are never panting, sweating or looking for shade and are actually comfortable because their merino fleece is cooling them.

Because merino wool creates a microclimate between the skin and the garment that prevents it from becoming moist, bacteria doesn’t thrive as much as when the microclimate doesn’t exist, for instance, when you wear cotton or polyester. Bacteria needs moisture to breed and this is why cotton and polyester starts to smell after the wearer is exposed to heat or exercise.

When merino wool is milled and the lanolin is removed during this process, a small layer of lipid remains on the surface of the fibre that has similar properties to many antibacterial products. More studies are currently being carried out by woolmark on this, but having a natural antibacterial finish helps stop the breeding of bacteria and therefore eliminates the nasty odours that you typically get wearing cotton and polyester garments.

Hopefully this help explain the current hype behind why our merino shirts outperforms cotton and polyester shirts. If you haven’t tried merino yet, then buy a shirt, wear it for a week without washing it. Walk faster to work or even commute to work by bike to work up a mild sweat and see how it remains odourless for the full week. You won’t be disappointed.