Wool absorbs sweat vapor and releases it on the other side, preventing clamminess. With synthetics, sweat must recondense before the fabric can wick it away.
Each wool fiber has crimps (bends or crinkles). This wave creates millions of tiny air pockets, which, in the cold, store body heat, keeping you insulated even when the fabric is damp.
As sweat evaporates from your skin (like steam from a kettle), it cools the skin and nearby air. Wool’s micropockets trap this chilled air, buffering you from searing ambient temps.
The fiber’s core is hydrophilic and can absorb one-third its weight in water. The waxy outside is hydrophobic. So wool sucks up H20, but still feels dry on skin.
Scales, stacked like cones, cover the fibers. Warm, soapy water causes them to slide to the root and interlock—hence, shrinkage. But modern factory prewashes smooth the fiber, so it doesn’t shrink.