HAIR DAMAGE 49 tested, and combing ease is a contributing factor to protein loss in this experiment. These results clearly show that the proposed methodology can be applied to different types of hair to study post-shampoo hair damage protection during combing. HALF-HEAD TESTS The above laboratory studies have shown that shampoo 5 provides superior hair pro- tection as compared to shampoos 6 and 7. To determine whether the laboratory findings on protein loss during combing are reflected under "real-life" conditions, these same test products were evaluated for hair protection efficacy in half-head tests using the proposed methodology described in the experimental section. As mentioned earlier, such tests provide a side-by-side comparison of the relative efficacy of any two of the test products. Two separate half-head tests were conducted to compare the hair protection efficacy of shampoo 5 vs shampoo 6 and shampoo 5 vs shampoo 7. Each study was a double-blind experiment using 40 healthy, adult, female subjects with 16-24-inch-long hair (see Materials and Methods for details). These studies were carried out in collaboration with an independent beauty salon. Protein analysis tests were done by an independent clinical laboratory using our protocol. The test results are summarized in Figures 6 and 7. As shown, protein loss from hair shampooed with shampoo 5 was found to be significantly less (p = 0.05) than from hair shampooed with shampoo 6 (Figure 6). Similar obser- vations were made with respect to shampoo 5 vs shampoo 7 (Figure 7). Although the main objective of the clinical protocol was to determine protein loss from hair during combing, the beauticians observed that in almost all cases the hair on the side sham- 100o 0 • o Shampoo 5 Shampoo 6 (Each value Is an average of forty subjects. Observed differences are significant at p=O.05 level) Figure 6. Half-head test: Post-shampoo protein loss during combing.

50 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS o 'o ! • '• 500 0 Shampoo 5 Shampoo 7 (Each value Is an avaraga of thirty-nine subjects. Observed differences are significant at p=O.05 level). Figure 7. Half-head test: Post-shampoo protein loss during combing. pooed with test product 5 was easier to comb as compared to the side shampooed with either test product 6 or test product 7. Because each study was double-blind, the beautician (or the panelist) did not know which product was used on which side. These clinical studies on "live heads" directly confirm our laboratory findings, verifying that the laboratory results do confirm the real-life practical damage protection offered by the protein loss measurements. CONCLUSIONS This paper describes a simple and sensitive technique to quantify damage to hair during combing. This method involves collecting cuticular protein fragments abraded from hair during combing, and quantitatively measuring the amount of protein by a colorimetric procedure capable of detecting as little as 5 Ixg of protein per mi. The proposed methodology is particularly useful in assessing the protection efficacy of various sham- poos and conditioners in protecting hair against damage due to abrasion during comb- ing. It can also be used to study the effect of chemical treatments such as permanent waving and bleaching on hair during combing. Using this procedure in the laboratory and in half-head tests, we were able to demonstrate significant differences (p = 0.05) in total protein loss induced by combing hair treated with different shampoos and conditioners. Laboratory studies show that among the five different shampoos tested, protein loss was the highest from hair shampooed with a non-conditioning shampoo, followed by the conditioning shampoo treatments. Additionally, even among the various conditioning shampoos tested, significant differences in protein loss were observed. This suggests that post-shampoo cuticle protection differs among shampoos. Furthermore, hair shampooed