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j. Soc. Cosmet. Chem., 32,437-458 (December 1981) Cleaning of hair MIKLOS M. BREUER, Gillette Research Institute, 1413 Research Blvd., Rockville, MD 20850? Received June 5, 1981. Presented at the Annual Meeting of the American Oil Chemists' Society, New Orleans, 1981. Synopsis Whereas the principles of cleaning of textile materials are well established, the same is not the case for human hair. Cleaning of hair occurs under constraints which are different from those imposed on fabric laundering: requirement of short time durations the necessity for using ambient temperatures and stringent human safety considerations with respect to the cleaning materials used. Also, consumers use different criteria for assessing the state of cleanliness of hair from those employed for textiles they depend, in addition to the quantity of the soil, on the physico-chemical properties of sebum. In addition to the amount of soil removed, the various attributes of the product (e.g., fragrance, color, etc.) and the rate of hair resoiling subsequent to shampooing also play an important part in judging shampoo efficacy. The resoiling rate depends on the consistency of the sebum and on the surface characteristics of hair after shampooing, both of which depend on the nature of the shampoo ingredients and their interactions with hair. The gaps of knowledge that exist in the mechanisms of hair cleaning and which require further research, have also been reviewed. I. INTRODUCTION Human hair has similar chemical composition, physical properties and histological structure to those of keratin fibers used in textile materials (e.g. wool, mohair, etc.) (1). Nevertheless, cleaning and washing of hair constitute a vastly different problem than the one encountered in the laundering of fabrics spun from keratinous yarns. When formulating a hair shampoo, certain restrictions must be kept in mind: a) the cleaning can only be carried out under physiologically acceptable temperatures, i.e., at about 40-45øC b) the time available for cleaning is relatively short (5-10 minutes compared to the 30-40 minutes that a laundering operation lasts) c) the detergents used in shampoos must meet stringent human safety standards (i.e., low skin and low eye irritancy, no sensitization or toxicity potentials, no extreme pH values, etc.) and d) the fact that the criteria for assessing the cleaning efficacy are different from those used for measuring cleanliness of textiles. ICurrent address: The Gillette Co., Personal Care Div., Gillette Park, Boston, MA 02106. 437