J. Cosmet. Sci., 61, 147–160 (March/April 2010) 147 18-MEA and hair appearance HIROTO TANAMACHI, SHINICHI TOKUNAGA, NORIYUKI TANJI, MASASHI OGURI, and SHIGETO INOUE, Beauty Research Center, Kao Corporation, 2-1-3, Bunka, Sumida-ku, Tokyo 131-8501 (H.T., S.T.), Analytical Science Research Laboratories, Kao Corporation, 2606 Akabane, Ichikai, Haga, Tochigi 321-3497 (M.O.), and Analytical Science Research Laboratories, Kao Corporation, 1334 Minato, Wakayama-shi, Wakayama, 640-0112 (N.T., S.I.), Japan. Accepted for publication August 13, 2009. Synopsis The effects of the removal of 18-MEA on the dynamic contact angle (advancing contact angle and receding contact angle) and friction force (friction force microscopy (FFM)) were examined in the present study. Chem- ically untreated hair tresses formed more fi nely ordered bundles, with the fi bers aligned more parallel to each other, in the wet state, and lying fl at and aligned parallel to each other in the dry state. Hair tresses in which 18-MEA had been removed by potassium t-butoxide treatment formed coarser tangled bundles and were aligned in a disorderly manner in the wet state, causing the hair to become entangled and disorderly in the dry state. This was because the 18-MEA-removed hair fi bers adhered to each other and were not easy to realign in the wet state. The distorted part of the bundle dried faster and the tress shape was eventually fi xed in the entangled shape. One role of 18-MEA is to allow hair fi bers to lie fl at and parallel with respect to each other in the wet state by providing relatively high receding contact angles and low surface friction. Hair alignment in the dry state is directly affected by hair alignment in the wet environment, particularly in the case of damaged hair. INTRODUCTION Healthy and beautiful hair is of interest to many females who have had their hair dam- aged by chemical processing, heat styling, and environmental factors. There are a lot of aspects that are required to make hair beautiful, of which the following three points are essential. The fi rst is appearance: shine, luster and high contrast. The second is hair align- ment, silhouette and how the hair moves i.e., whether hair fi bers can move smoothly and separately, e.g., when the wind blows. The third is texture: a silky and smooth feel. It seems very important that each of these attributes has to be present to some degree to provide beautiful hair. The cuticle forms the outer surface of the hair fi ber, protecting the cortex. The cuticle consists of fl at overlapping cells that are attached at the root end and point toward the tip end of the hair fi bers, like tiles on a roof. The shape and orientation of the cuticle cells are responsible for the differential friction effect in hair (1). The outermost surface of the