Why Does Wool Fabric Offer Excellent Warmth?

The exceptional warmth retention of wool fabric stems from the combined effect of the structural characteristics of wool fibers and the air-trapping capacity within the fiber assembly.

The natural crimp of wool fibers traps still air. Wool fibers have a distinctive wavy, crimped structure. When numerous crimped fibers interlace, they create countless tiny spaces within the fabric. Since air is a poor conductor of heat, these layers of still air effectively prevent body heat from escaping while blocking external cold air, forming an insulating air layer. The higher the crimp of the fibers, the more air is trapped, and the better the warmth retention.

The scaly and hollow structure of wool fibers reduces heat loss. The surface of wool fibers is covered with a scaly structure, which slows down air convection and further minimizes heat dissipation. Some wool fibers (such as cashmere) also feature a hollow core. This structure enhances air retention capacity while reducing the overall density of the fabric, providing warmth without sacrificing lightness.

The moisture-absorbing and heat-generating property of wool contributes to a warming sensation. Wool fibers possess excellent moisture absorption, actively drawing moisture (such as sweat) from the skin's surface. During the moisture absorption process, wool undergoes a slight chemical exothermic reaction, releasing a small amount of heat. This helps keep the wearer warm and dry even in damp conditions, avoiding the chill caused by trapped moisture.