I’ve stopped wearing merino base layers. The change wasn’t deliberate, sudden, or driven by a deep concern for the wellbeing of rare sheep. Instead, it happened naturally over time, because the latest generation of synthetic next-to-skins genuinely offers superior performance.
A unique mix of performance attributes have always made wool the go-to long underwear. It remains warm when wet, resists odor, actively wicks moisture away from your skin, and helps regulate temperature, keeping you warm when you’re resting and cool when you’re moving.
And the ways in which wool does all that can—if you forget that it’s a natural material for a moment—sound surprisingly high-tech. Take wool’s ability to actually generate heat, for instance. While its scaly outer layer repels water droplets, a wool fiber’s hollow interior is actually hydrophilic: it attracts and absorbs water vapor. And, once water gets inside those fibers, their rough texture actually breaks apart the hydrogen and oxygen molecules, creating a chemical process that produces a small amount of heat.
Merino carries many of the same performance…
