The hair surface, with its overlapping cuticle scales, represents a substrate where friction can be assessed through various direct or indirect instrumental methods [1][2][3][4][5][6][7] helping the evaluation of its potential alteration by, for example, external factors such as excessive heat, sun exposure, or washing. [8][9][10] These in vitro methods can be performed on a single hair fiber or, alternatively on hair swatches standardized in length and weight, that group hairs of different shapes (straight, wavy, kinky), status (natural, oxidized, perm, straightened...), or diameters/cross-sections.The nature and shape of individual hair fibers together with the 3D arrangement of the ensemble of hairs on the human head, both contribute to its overall appearance as well as to its sensorial perception when handled or touched. The vibrations induced by friction 11 or the visual aspect or touch of an assembly of fibers can lead to different subjective interpretations. In addition, this perception may