QUANTITATIVE ESTIMATION OF DETERGENCY OF SHAMPOOS 659 amount of detergent left. However, three of the four combinations of con- ditions gave effectively the same result and only when a long shampoo time was followed by a short rinse time was there a significant increase in the detergent remaining on the wool. With product (b) no effect of shampoo time or rinse time was dis- cernible at the replication used. However, one can see that, at least in some cases, net detergent retention may be strongly influenced by the presence or absence of soil on the hair and that the extent of this retention may be governed by the conditions of shampooing and rinsing. CONCLUSION Quantitative assessment of shampoo properties and behaviour under completely realistic conditions are extremely difficult. Under such con- ditions soiled hair itself would have to be used and, ultimately, hair clippings straight from the head. This clearly introduces problems of the uniformity of the material studied {namely, the hair) as well as in the development of techniques suitably refined to measure any changes in the hair which could be interpreted in a meaningful way. The approach des- cribed in this paper, although not completely realistic (in that wool is used on the hands, rather than hair on the head), is believed to be a reasonable initial compromise between manageable technique and the use of actual conditions. Notwithstanding the difficulties involved in using soiled hair clippings, or taking samples from a head during the course of a shampoo, an attempt to adapt the method to the use of hair itself might prove worthwhile. ACKNOWLEDGEMENT The authors wish to acknowledge their thanks to Mrs. S. Gibson for her willing co-operation in those parts of the experiments carried out in the hairdressing salon. (Received: oe4th August 1966.) REFERENCES (1) Barnett, G. and Powers, D. H. J. Soy. Cos,netiv Chemists •, 219 (1951). (2) Gould, E. Anal. Chern. 84 567 (1962).

660 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Introduction by Mr. Brasch The work reported here arose out of various attempts to study some of the fundamental aspects of hair conditioning and the mechanisms involved, with due regard to the practical conditions under which shampoos are used. There is quite a deal of published work on laboratory results concerning the physico-chemical behaviour of a whole range of compounds in relation to hair, as well as a whole legion of results of similar type of work done on wool. Such results on wool are often used as the basis of discussions about the actions of shampoos, whether conditioning or otherwise. It seemed to us that one useful first approach would be to choose some simple variables which are easily estimated and to use these to test whether some of the factors which one would expect to operate during shampooing do in fact do so to any significant extent. After all, one would expect the intensity of shampooing, that is to say the degree to which you rub the head, to bear some relation to the amount of soil removed from the hair and again it would seem obvious to suspect that time of shampooing and time of rinsing play some important part. At the outset we wanted to obtain some measure of the effect of these factors. There are quite a number of variables which could be measured, some of which require fairly sophisticated techniques. We chose detergency and detergent retention but these are by no means the only variables which are measurable after shampooing nor indeed are they the only relevant ones for an understanding of conditioning effects. Surface characteristics of hair, 'rigidity-modulus and various other things obviously also play a very important part. In a system as complex as that existing on the head during the course of a shampoo one can reasonably accept the fact that there is bound to be a gap, as it were, between an actual situation on the head and the way it is assessed by the particular technique. This gap is bound to exist no matter how sophisticated the technique used to study these effects and how many factors are thought to have been taken into consideration in devising the technique. We suspected that in a study such as this the main causes of variation would lie in the system itself and that such a variation would not justify the use of techniques designed to measure very sensitive changes in behaviour. In choosing a quantitative assessment it seemed better, at least to start with, to err on the side of simplicity. In the conclusion of the paper we suggest the extension of this technique and the whole approach to the use of hair itself. We have followed this up to some extent, although unfortunately circumstances did not allow us to continue to study it as fully as we would have wished. Nevertheless, the results we did obtain on hair are to be published (3). An interesting feature which arises out of the further work and in line with some results obtained by Ester and Longfellow (4) is the relatively small amount of fatty matter removed from hair during shampooing, something like 40% of the original amount present on the hair. This obviously points to the need for care in interpreting the sort of results we obtained using wool bundles because our wool bundle technique did, in fact, give us very much higher figures for the removal of fatty matter by shampooing. (3) Brasch, S. V. and Arnoore, Miss J. A. J. Soc. Cosmetic Chemists 18 31 (1967). (4) Ester, V. C. and Longfellow, M. Drug Cosmetic Ind. 74 354 (1954).