22 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS (10) Bradbury, J. H. and Chapman, G. V. The chemical composition of wool. I. The separation and microscopic characterization of components produced by ultrasonic disintegration. Aust. J. Biol. Sci. 17 960 (1964). (11) Robbins, C. R. and Kelly, C. H. Amino acid composition of human hair. Text. Res. J. 40 891 (1970).

J. Soc. Cosmet. Chem. 25 23-31 (1974) ¸ 1974 Society of Cosmetic Chemists of Great Britain The substantivity of cosmetic ingred- ients to the skin, hair and teeth N.J. VAN ABBE* Presented on the 12th February 1973 in London, at the Symposium on 'Some surJbce chemical aspects of cosmetic and toiletry products', organized by the Society of Chemical Industry and the Society of Cosmetic Chemists of Great Britain. Synopsis--SUBSTANTIVITY conveys the idea of prolonged association between a material and a substrate, an association which is greater or more prolonged than would be expected with simple mechanical deposition. This review is intended to discuss the advantages and disadvan- tages of substantive effects, various ways of achieving substantivity and methods for its detection and assessment. THE NEED FOR SUBSTANTIVITY Lipstick is a typical example of decorative make-up which is left at the site of application for many hours. The effect of pigmentation is mainly achieved by purely mechanical deposition. In much the same way, various 'toiletries' are applied in a matter of seconds, or perhaps for a minute or two we then expect them to have an effect throughout the whole day or even longer. However, such preparations --for example, shampoos and toothpastes--are often rinsed away with copious amounts of water immediately after application. Sunscreens are not deliberately rinsed off in this way, but they are expected to retain their screen- ing effect even after the body has been completely immersed in seawater. So it is evident that substantivity could be extremely helpful in the cosmetic and toiletries field, to assist in providing long-lasting benefits. * Beecham Products, Applied Research and Evaluation Unit, Randalls Road, Leatherhead, Surrey. 23