Keeps warm in cold & cools in heat
Merino wool fibers are naturally crimped and create more air pockets than other fibers. And this trapped air insulates against the cold and keeps you warm, even when wet.
Merino wool fibers naturally retain moisture. When the weather is warm or you heat up from exertion, the wool is warmed and the moisture begins to evaporate and cool the skin. Best of all, as you get warmer and produce more sweat, the evaporative effect of the merino increases to cool you even more
Pro Tip: Merino wool and synthetics wick moisture, but only merino has the natural ability to wick moisture away from your skin before it condenses.
Merino wool is one of the most breathable materials around. Breathability is important in a sock because it allows sweat to escape and keeps your skin dry and blister-free. You may think it's just a woven fiber that has plenty of room for vapor, but merino has several unique properties that enhance breathability.
Wearing a merino wool sock allows initial sweat to escape as vapor, but when perspiration builds or you step in a puddle, merino wool mechanically wicks moisture away, using capillary action to move it away from your skin. This keeps your socks drier and protects your skin from irritation and blisters.
Because merino wool is so breathable and conducts so efficiently, your socks dry quickly. This is especially nice on a multi-day hiking trip, as you can wash your extra pair of socks and let them dry while you hike.
We already mentioned merino wool's ability to absorb an incredible amount of moisture before it gets wet, and that's because the inner core of the fiber can absorb up to a third of its weight in moisture, but the surface of the fiber actually repels moisture. Merino wool fibers naturally have a wax-like coating that repels water, allowing it to bead up and roll off instead of soaking into the socks. And nature has made merino's wax coating so durable that it won't be removed by regular washing.
Merino wool naturally resists odors and bacteria thanks to the amazing moisture management properties we just discussed. Merino wool breathes, wicks and dries quickly, inhibiting odor-causing bacteria. This makes wearing merino wool socks a big plus for backpacking.
Most people don't realize that merino wool is hypoallergenic. The dust mites that irritate many allergy and asthma sufferers thrive in warm and moist materials, such as cotton and synthetic fibers. Because merino dries quickly, it is not an appealing environment for mites. It should be noted that in rare cases there are cases when people are directly allergic to wool, but for the majority of allergy sufferers merino wool is hypoallergenic and a good choice.