28 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS What does a rough cuticle mean cosmetically (2)? a) increasing roughness will diminish the gloss of hair b) the combing resistance may increase and, therefore, the electrostatic properties of the hair may change c) its potential to adsorb dust and chemicals may increase d) the frictional properties will change. Therefore the surface profile should be related to physically measurable parameters like "combing force" and to subjectively evaluated parameters like "body." MATERIALS AND METHODS INSTRUMENTS The measurements reported here were performed by means of a commercial profilo- meter. The scan speed was generally 1 mm/sec. The preferred stylus had a 0.75-mm broad edge, a radius of curvature of 2.5 •m, and an angle of 60 ø (Figure 1). In a few cases a conventional pyramidal stylus with a curvature of 1.3 •m and an angle of 90 ø was used, when investigating short distances (Figure 2). The following parameters were taken to characterize the surfaces: R t (•m), Rp (•m), R a Figure 1. Scheme of measurement using axe-shaped stylus. Dislocation of stylus during scanning (ver- tical), • . Direction of scan (horizontal), •.

PROFILOMETRY OF HAIR 29 Figure 2. Scheme of measurement using pyramidal stylus. Dislocation of stylus during scanning (vertical), $ . Direction of scan (horizontal), ---. (}xm), Rq (}xm), Pc (peaks/cm) and Aq (for definition see (3)). Aq is a measure for profile length, Pc for peak density. The suppression of waves while determining roughness was either done by electronic filters (4) or by treating unfiltered profiles by digital filtering software (5). SAMPLE PREPARATION Most of the hair fibers tested were obtained from small strands cut above the scalp behind one of the ears and marked according to the direction of growth. Single hair fibers were fixed to microscope slides: a) the glass slides were placed on top of checkered paper, glass edges being parallel to the lines on the paper b) the tip of the fiber was fixed to the slide by adhesive tape c) the other end was loaded with a clothes peg weighing 6.2 grams (constant preten- sioning force) the hair was adjusted parallel to the slide edges d) two drops of nail lacquer fixed the hair to the slide in case of later treatments the hair was fixed over its whole length by a thin film of nail lacquer in the case of vertical measurements two (or several) drops of lacquer fixed neighboring segments -- 1 mm distance--of the fiber (6) e) to determine the extent of swelling of hair fibers caused by aqueous media, the fibers