Mechanical profilometry of wool and mohair fibers

In the scanning electron microscope, the surface of wool fibers is much rougher than that of mohair or other specialty fibers, mainly due to differences in the frequency and height of the cuticle scales. In order to assess and quantify these differences, which are essential for the perception of 'roughness' and thus for fast fiber discrimination, mechanical profilometry is used to assess coarse Merino wool and Texas mohair fibers. The data are analyzed by smoothing and Fourier analysis to separate cuticle-related effects of roughness from longer term fiber diameter changes attributed mainly to the characteristic circadian (daily) biological rhythm of the animal. The results show that subjectively observed differences in the roughness of the two fiber types are reflected in roughness and frequency parameters obtained from their mechanical profiles, enabling reliable discrimination between wool and mohair.