LOAD-ELONGATION OF HAIR COILS 239 (6) L. Rebenfeld, H. D. Weigmann, and C. Dansizer, Temperature dependence of the mechanical properties of human hair in relation to structure,J. Soc. Cosmet. Chem., 17, 525-538 (1966). (7) Robbins, pp 173-174. (8) P. Alexander, et aL, pp 55-57. (9) H. Bogaty, Torsional properties of hair in relation to permanent waving and setting, J. Soc. Cosmet. Chem., 18, 575-589 (1967). (10) Design and Application of Helical and Spiral Spring, ASE J795a, Soc. of Automotive Engineers, Inc. (1973). (11) C. H. Goulden, Methods of StatisticalAnalysis (John Wiley and Sons, Inc., New York, 1952), p 144. (12) C. R. Robbins and G. V. Scott, Prediction of hair assembly characteristics from single fiber properties, J. Soc. Cosmet. Chem., 29, 783-792 (1978).

j. Soc. Cosmet. Chem., 34, 241-253 (August 1983) Facial oiliness and dryness: Correlation between instrumental measurements and self-assessment MICHAEL S. CHRISTENSEN and SERGIO NACHT, Dermatological Research Department, Vicks Research Center, Shelton, CT 06484 ELIAS W. PACKMAN, Philadelphia College of Pharmacy and Science, Philadelphia, PA 19104. Received February 4, 1983. Presented at the Annual SCC Meeting, New York City, December 2-3, 1982. Synopsis The facial skin of many individuals is excessively oily in some areas, excessively dry in others. Skin care products for general use thus need to be compatible with both oily and dry skin. Formulating such compatible products requires accurate, objective assessment of oiliness and dryness in vivo. Oiliness is assessed by measuring skin surface friction this characteristic varies on different parts of the face, and it may be altered by product application. The forehead and nasal fold areas were found to be oilier than the cheeks, and an inverse relationship was shown between perceived oiliness and skin surface friction. Drying effects are assessed by measuring the increased stiffness (tautness) of the stratum corneum which may result, for example, from ordinary washing with soap and water, or from application of products which have a drying effect on the skin. Changes in skin surface stiffness are more readily demonstrated on the cheeks than on the forehead, although baseline stiffness is found to be greater on this (latter) site. In this assessment, we use a gas-bearing electrodynamometer suitably adapted for measurements on the face. Objective measurements made with these instruments correlate well with self-assessment of facial oiliness and dryness. INTRODUCTION We have used both instruments and trained panelists, as appropriate, for objective measurement of skin characteristics. In this paper, we will show how in vivo instrumental measurements can be used to quantitate two familiar facial skin conditions: (1) the stiffness of a "dry" horny layer, and (2) the.oiliness associated with excess sebum on the skin. The latter is cosmetically unacceptable to many individuals. The two conditions--oiliness and stiffness--are measured with instruments which have been described in prior work (1-2): the Newcastle friction meter, which measures the coefficient of the friction generated when a Teflon wheel rotates in contact with the skin surface, and the Gas Bearing Electrodynamometer (GBE), which assesses stiffness by measuring the resistance of the skin surface to shear. 241