The effects of humidity, ageing, annealing, and tensile loads on the torsional damping properties of wool fibers have been measured. The torsional damping increased with humidity and decreased with ageing and annealing. Wetting removed the effects of ageing and annealing, and no residual change to the fiber torsion properties was retained after annealing and wetting. Torsional damping in Merino fibers was very sensitive to applied stress and tensile loading produced changes in torsional damping similar to the de-aging effects of wetting. This effect suggests that high torsional damping following tensile stress is related to mechanical de-aging of the matrix in the wool fiber.