Wool fibers are subjected to severe mechanical processing following scouring, which results in physical damage. This study investigates the role of physical processing in changing the physical and chemical properties of the fibers. Removal of surface-bound lipids following physical processing is minimal, but there are significant morphological changes related to an increase in the chemical susceptibility of the fibers to chemical attack. The finding is demonstrated by the more effective removal of bound lipids from fibers in the form of top than from aqueous scoured fibers.