By Lavinia Calvert | February 2011

Merino is a particular breed of sheep prized for its very fine fiber wool. Measured in microns, merino is typically between 13 and 24 micron – the smaller the number, the finer. That might not mean much until you realize that the average human hair is about 60 micron. So we're talking about a fiber that is between two and five times finer than the average human hair. You'd think that would make it weak. No, quite the opposite. Merino fibers can be bent up to 30,000 times without breaking – so its core structure produces the most amazing blend of properties: exceptional softness and resilience. That's pretty cool.

But that's not all there is to love about merino. There are several other unique and inherent properties of merino that make it such a superb, natural fiber to work with, especially in a performance apparel application. It's hydroscopic – which means it is capable of absorbing moisture vapor and repelling liquid at the same time. This explains why when you wear merino next-to-skin, you can sweat a lot but not feel damp and clammy. The merino, which is capable of storing around a third of its own dry weight in water vapor, draws sweat away from your skin (a process known as wicking), absorbs and desorbs the vapors, speeding up the body's own cooling system while remaining dry to touch. The result is that you get to stay cooler and drier for longer.

Kind of like having your own temperature regulator, merino is an active fiber that adjusts its own equilibrium as conditions around it change. In other words, it helps you optimize your physical body temperature to atmospheric conditions making it cool to wear in the heat and warm to wear in the cold. So you're more likely to stay at a comfortable temperature throughout your training session and less likely to suffer post-training chills.

Moreover, with its unique physical and chemical structure, merino is naturally odor and soiling resistant, and anti-bacterial to boot. What many people don't realize is that it's not the sweat that has the odor – it's sweat left on the skin that has time to develop bacteria that creates the unpleasant smell. This is why the natural wicking property of merino makes it such an effective weapon against odor. It reduces the opportunity for bacteria and odor to build up, so you don't need to sweat the stinky stuff!

Less sweat, less soiling and no residual build up of odor means less washing is required – nirvana for most of the people I know who own a gi.

So when we talk about Gimono performance gi being breathable, comfortable, durable and easy care – it's largely thanks to the magic of the fine layer of merino we've put on the next-to-skin surface of Fortitude® that we get to make such claims. Without it, you'd just have another hot, sweaty, smelly gi!