J. Soc. Cosmetic Chem, ists 18 651-662 (1967) •) 1967 Society of Cosmetic Chemists of Great Britain The quantitative estimation of the detergency and allied properties of shampoos in practice S. V. BRASCH and MISS J. A. AMOORE* Presented at the Symposium on "Product Testing", organised by the Society of Cosmetic Chemists of Great Britain in Eastbourne, Sussex, on 15th November 1966. Syn0p$is--A method is described whereby small bundles of standard wool yarn, spun in the grease, are tied to the underside of the phalanges of a hairdresser's fingers and the weight loss determined after the completion of a shampoo under specific conditions. Detergent retained by the wool under these conditions may also be estimated. The results indicate how this method might be used to study the mechanism of tha shampoo operation and the variable effects it produces, even under controlled conditions. The use of this method is also suggested as an aid in the evaluation of specific products. Implications of the type of results obtained are briefly mentioned. INTRODUCTION Assessment of various properties of shampoos under practical conditions is generally made subjectively. Thus, where a hairdressing salon is available, the hairdresser is able to obtain an impression of the lather formed during washing, by feel, and may subsequently judge, by eye, such features as "fly away" and gloss, whilst combing the dry hair, and on the final coiffure. Various methods of scoring may be used to compare these properties from one product to another. It is extremely difficult to obtain fully quantitative measurements of shampoo properties or associated parameters, under completely practical *Beecham Toiletry Division, Brentford, London. 651

652 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS conditions. This is due to the complexity of the physico-chemical factors making up these properties and the apparatus needed to measure them. A relatively simple technique giving some quantitative indication of the behaviour of a particular shampoo in practice is therefore desirable, even if the information obtained therefrom covers only a limited aspect of the total properties of a shampoo. Direct detergency measurements on shampoos or their detergent bases under practical conditions may be used as indicators of some of the ways in which they behave. Such measurements have the additional advantage of being quite readily carried out and they may also be used to evaluate some of the controllable factors in shampooing. EXPERIMENTAL The method is based on the gravimetric estimation of removable soil from A.A.T.C.C. standard wool yarn, spun in the grease (1), obtainable from the Lowell Textile Institute, Lowell, Mass., U.S.A. The total soil content of the yarn was found by taking samples (0.Sg) at intervals throughout each of two skeins weighing 1 kg and extracting (4 hr) in turn with ether and alcohol, followed by repeated washing in distilled water at room temperature. The weights of the samples were determined before and after the treatment, after drying to constant weight in a vacuum oven at 65øC over phosphorus pentoxide. Drying to constant weight under these conditions generally took five hours. Weight loss was expressed as a percentage of the dry, soiled weight. The figures below show the results obtained on the actual material used, together with the number of samples taken. The Standard Deviation of the results is also given. The two skeins came from deliveries about three years apart so that the figures also show the uniformity of the material over a period of time. Percent Removable Soil in A.A.T.C.C. Wool Skein (1) Skein (2) 10.00 (S.D.=0.52) 9.66 (S.D.=0.26) (Mean of 11 results) (Mean of 6 results) Grand Average = 9.83 (S.D. =0.41) All detergency figures in the subsequent work were expressed as percentage weight loss of a particular sample, without further recourse to control determinations of total removable soil by extraction and washing. This appeared justifiable in view of the small spread of the above results for total removable material. Further justification for this step was afforded