14 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS ACKNOWLEDGMENT We should like to thank Mr N.J. McNeice who carried out the experi- mental work. (Received: loth February 1975) REFERENCES (1) Harper, R. Human senses in action (1972) (Churchill Livingstone, Edinburgh). (2) Levitt, D. J. J. Scoe Food Agr. 24 739 (1973). (3) Bradley, R. A. and Terry, M. E. Biometrika 39 324 (1952). (4) Sherman, P. Industrial rheology (1970) (Academic Press, London). (5) Haighton, A. J. J. Am. Oil Chemists' Soc. 36 334 (1959). (6) Suzuki, K. and Watanabe, T. Amer. Perfum. Cosmet. 85 115 (September, 1970) (7) Barry, B. W. and Grace, A. J. J. Pharm. Sci. 60 1198 (1971).

J. Soc. Cosmet. Chem. 27, 15-45 (1976) ¸ 1976 Society of Cosmetic Chemists of Great Britain Instrumental colour assessment Some practical experiences D. A. WHEELER, D. A. MOYLER and J. T. THIRKETTLE* Presented at the Symposium on 'A Sensory Approach to Cosmetic Science' organized by the Society of Cosmetic Chemists of Great Britain at Manchester on 7-9th April 1975 Synopsis--INSTRUMENTAL COLOUR ASSESSING techniques promise the cosmetic colour chemist many advantages over the traditional, subjective methods. The authors have examined a range of INSTRUMENTS operating on a variety of principles, including ABSORPTION and REFLECTANCE SPECTROPHOTOMETRY and TRI-STIMULUS COLOUR SPACE. Practical experience has shown that some of these promises have been fulfilled and that instru- ments can provide valuable aid to the human colour assessor without being able to replace him entirely. In particular, by providing numerical data on a subjective phenomenon, instruments can increase the speed of colour correction and confidence in the acceptability of a commercial match. INTRODUCTION Of all the human senses, the phenomenon of colour vision is the one which has yielded up its secrets most readily to patient scientific examination. Whilst it would be an exaggeration, even today, to say that we understand all aspects of colour vision, sufficient was known about the human response to light stimuli by 1925 to enable purely instrumental 'measurement' of colours to be made. Instrumental colour assessment was pioneered largely by textile and paint companies and since those early days such techniques have gained * Yardley of London Ltd, Miles Gray Road, Basildon, Essex. 15