A QUANTITATIVE METHOD FOR THE EVALUATION AND STUDY OF SHAMPOOS* By G. BARNETT and D. H. POWERS 1/Farrier-Hudnut Co., Inc., New York City, N.Y. THERE HAS been a great deal of work on the evaluation of deter- gents (I), and the recent paper by Lambert and Sanders (II), high- lights some of the limitations of the present methods for laboratory test- ing detergents for use on cotton. It is a surprising fact that Crowe (III) was particularly pessimistic after a five-year study of detergent evalua- tion, sponsored by A.S.T.M., when it turned out that some laboratories found water more effective than cer- tain detergents. While the evalua- tion of detergents on cotton has had a tremendous amount of study (IV) in the past ten years the cleansing action of shampoos has received relatively little study and the prob- lem in many respects is more com- plicated than the problem of cotton detergents. PRECISION VS. ACCURACY In any test or study of shampoos we have the problem of precision and accuracy--the precision of the study itself an•t reproducibility of the results obtained, and the accuracy of the test method as a means of evaluating shampoos. Certainly in this field it is essential that we first set up a method of high precision and then study its accuracy in evaluating commercial products. Our own work in this field has shown that it is possible to set tip what appears to be a method of good precision with excellent re- producibility and effectiveness, but many commercial shampoos ap- pear to be no more effective than water by this test and careful re- check by the method confirms this finding. COMMERCIAL SHAMPOOS INEFFECTIVE We are forced to the conclusion that many of the successful and popular shampoos are relatively ineffective as cleansing and scour- ing agents and that in a shampoo the primary requisite is one of im- parting a lustrous, soft finish to the hair rather than one of eftqcient cleansing. Further consideration of the problem of shampoos sug- gests that the ideal shampoo would * Presented at the December 5, 1950, Meeting, New York City. 219

220 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS leave more "deposit" on the hair after shampooing than before the washing process. Actually a good shampoo should remove the dirt and grease on the hair and impart a deposit on the hair of a condition- ing oil which improves combability and imparts a luster and high- lights. CONSUMER THE GmNEA We believe that a shampoo should .act as an efficient, effective cleanser but in view of the lack of any satis- factory test method, manufacturers have been forced to judge a shampoo in terms of consumer reaction, and the consumer is indeed a poor sub- ject for evaluating cleansing ef- ficiency. In view of the lack of adequate test methods, commercial shampoos have become poorer and poorer cleansing agents and better and better "finishing" agents. It is interesting to note that recent sur- veys of shampoos run by the various women's magazines, assumed that shampoos exerted a cleansing ac- tion and devoted their efforts to determine the accessory characteris- tics which are desirable, such as luster, softness, fragrance, and suds- ing action. USE OF GREASE WOOL YARNS A careful review of the work done on deterMents (V), particularly with reference to the removal of carbon black from cotton fabrics, clearly indicates that the so-called "stand- ard soils" of this type have little interest or significance in the study of shampoos, and the development of a standard soil on hair would appear to be a difficult problem and require a controlled deposit of lanolin on the hair. A number of difficulties are apparent in the development of such a uniform test. However, we have been greatly assisted by Mr. A. G. Ashcroft, Director of Research at Alexander Smith & Sons Carpet Co., and his assistants working with Mr. E. A. Leonard, who have been studying a quantitative test method for evaluating deterMents (VI) for use in wool scouring. The scouring of sheep's wool in the grease is much more closely related to the problem of shampooing hair than is the prob- lem of removing carbon black from cotton fabrics, which has been so widely and generally studied in the evaluation of deterMents and soaps. The composition of wool grease has been carefully examined by Weit- kamp (VII) and its removal stud- ied by Lundgren (VIII). It is un- questionably similar to the grease and sweat on human hair. By re- ducing the pH by the elimination of sodium carbonate, we are able to approach test conditions closely paralleling conditions encountered in the shampooing of hair. We are particularly fortunate in that Alexander Smith & Sons have recently developed a method of spin- ning "wool in the grease" and pro- ducing a wool yarn containing a wool grease content of 6 to 10 per cent. It is our understanding that Alexander Smith & Sons are pre- pared to produce wool "yarn in the grease" in quantity and that it may