Returning to the same area of hair surfaces before and after treatment: a longitudinal AFM technique.

We report the use of longitudinal (aspect ratio > 1 : 1) scanning atomic force microscopy as an aid in returning to the same area of hair fibres after bleaching, treatment with a commercial shampoo or the application of a 'leave-on' conditioner product. The bleaching treatment used in this study was not found to affect the cuticular architecture and lateral force microscopy (LFM) also showed little difference after treatment, reflecting the homogeneity of the newly revealed surfaces. After treatment with a commercial shampoo, the hair sample again showed very little difference in topography or lateral force characteristics. Hair treated with the leave-on conditioner product also showed no major topographical changes. LFM traces, however, showed regions between the ghost edge, marking the original position of the scale edge before cuticular erosion, and the existing scale edge, to have higher frictional properties than distal regions of the cuticle. A thin film of the leave-on product thus seems to form in this region and extends from the foot of the scale edge.