356 JOURNAL OF COSMETIC SCIENCE test results (Figure 5), it was shown that 0.21%, 0.42% additions of amodimethicone, and 0.18% addition of silicone quaternium-18 reduced the hair combing force and hair became smoother. During combing, the force needed for combing through hair swatches became smaller, therefore the damage caused by physical combing was reduced. Figure 9 shows the tensile strength test results on Asian damaged hair. Our hypothesis was that the deposition of amodimethicone and silicone quaternium-18 could repair hair damage and therefore increase tensile strength of damaged hair. Addition of 0.21% amodimethicone (S2) in shampoo slightly increased the maximum load of hair to be broken compared to base shampoo (S1) sample without silicone. A similar result was obtained for hair treated by shampoo S4, which added 0.18% silicone quaternium-18. The hair treated with shampoo S2 required a longer time to be broken compared to S4, although their maximum loads to be broken are similar (Table II). We are not certain of the reason. Enlarged View S1 Enlarged View S4 Enlarged View S3 Enlarged View S2 Figure 8. Hair breakage test results on Asian damaged hair. S1: base shampoo without silicone S2: shampoo with 0.21% amodimethicone S3: shampoo with 0.42% amodimethicone S4: shampoo with 0.18% silicone quaternium-18. Table II Number of Broken Hairs Counted, and the Reduction Rates Compared With Base Shampoo in Hair Breakage Test Hair Broken Time and Maximum Load When Broken in Tensile Strength Test Testing samples S1 S2 S3 S4 Hair breakage test No. of broken hairs counted 228 38 29 39 Reduction rate versus S1 -83.3% 87.3% 82.9% Tensile strength test Broken time(s) 47.1 52.4 -50 Maximum load (N) when broken 0.9937 1.0458 -1.0511 S1: base shampoo without silicone S2: shampoo with 0.21% amodimethicone S3: shampoo with 0.42% amodimethicone S4: shampoo with 0.18% silicone quaternium-18.

357 Silicone Reduce Combing Force, Flyaway, Damage in Shampoo The hair breakage and hair tensile test results indicated that treating the damaged hair with amodimethicone and silicone quaternium-18 added to shampoos helped improve the strength of damaged hair, indicating damaged-hair repairing effects of the silicone. DIGITAL MICROSCOPE OBSERVATION AND SILICONE DEPOSTION TEST RESULTS Figure 10 shows the digital microscope observation image of Asian damaged hair samples after washing 28 times with each shampoo sample. We have hypothesized that the deposition of amodimethicone and silicone quaternium-18 could improve the hair surface smoothness the microscopy image demonstrated this. From the image, we observed that in hair washed with the base shampoo sample (S1) the hair cuticles are not coated, some parts of the hair cuticles are removed, and the hair surface looks very rough, not shiny. For hair samples washed with S2 (0.21% amodimethicone), S3 (0.42% amodimethicone), and S4 (0.18% silicone quaternium-18), we can observe that the cuticle is uniformly coated, and the hair surface appears very smooth and has a natural shine. This confirmed that amodimethicone and silicone quaternium-18 can form a thin film on the hair surface, and this thin silicone film on the hair surface improved the hydrophobicity of damaged hair and thus shows the damaged hair-repair effect of amodimethicone and silicone quaternium-18. In addition, the thin film of silicone coated on the hair surface improved the smoothness of the hair surface, resulting in the wet and dry combing force reduction. This thin silicone film is also related to the improvement of hair tensile strength and hair breakage rate. Figure 11 shows the silicone deposition test results of Asian natural hair and damaged hair washed by each shampoo once. All the deposition data were extracted from the baseline that was deposition data of hair swatches cleansed by 10% SLES solution. We observed a small quantity of silicone deposition on damaged hair for S1, the base shampoo without silicone we assumed that it was error inherited from the difference of the hair swatch itself. 0.000 0.200 0.400 0.600 0.800 1.000 1.200 1.400 0 10 20 30 40 50 60 Time (s) S1 S2 S4 Figure 9. Tensile strength test results on Asian damaged hair. S1: base shampoo without silicone S2: shampoo with 0.21% amodimethicone S4: shampoo with 0.18% silicone quaternium-18. Load (N)