EVALUATION OF HAIR DAMAGE 367 tioning may modify the fiber surface due to deposition of surfactants and particularly of conditioners. The effect of grooming on work of adhesion was established only on the sample bleached four hours in 6% H202. We chose this sample because we expected the most damaged hair to be most susceptible to secondary damage from subsequent grooming treatments. Typical traces of work of adhesion along the distance scanned are shown in Figure 13. Besides differences in wettability, the traces show qualitative differences that are nota- ble. The regularity and amplitude of "chatter" differ among the treatments, and these patterns were consistent among the samples of a given treatment. The traces for the combed only and the shampooed and combed samples are more irregular than for the ungroomed samples, which may indicate subtle physical surface changes. The chatter for samples that were shampooed, conditioned, and combed is extremely regular compared 150 t25 100 15C C12• z - 10C (b) Combed (4B1) 50 o (a) New sample (4B0) 20. I meniscus traverse, cm 0•.1 0•.2 0.,3 meniscus traverse, cm t75 , , (C) Shampooed (4B2) 150 2cr• 125 75 50 0.1 0.2 meR[scus •rQverse, cm 175 / ' (d) Shampooed/combed (4B3) 150 f _•125 .....................................................I20'125261 100t- 75 o' I 50 / (e) Shampooed/conditioned/combed (4B4) 175 150 100 75 50 0.1 0.2 0..3 0 0.1 0.2 meniscus traverse, cm meniscus traverse, cm Figure 13. Water wettability of bleached hair before and after grooming sequences.

368 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS to any other group of samples. This suggests the deposition of conditioner-surfactant complexes on the fiber surface, which release surface-active compounds during the wettability scan (13). Materials can accumulate on hair surfaces from a number of cosmetic applications and environmental sources for example, conditioning polymers are deposited from sham- poos and conditioner formulations. Previous studies at TRI on many different condi- tioning polymers have shown that most of the excess conditioner polymers rinse off in successive water immersions (14), although conditioner-surfactant complexes can lead to considerable buildup in multiple applications (15). The average values of work of adhesion provide additional information about changes on the hair surface. Figure 14 shows the work of adhesion for the grooming sequences on the highly oxidized hair sample. As shown above, bleaching destroys the hydrophobicity of the untreated fiber surface, rendering it quite hydrophilic. As seen for combing of these fibers, two of the combed samples, 4B 1 (combed only), and 4B3 (shampooed and combed), significantly lowered the work of adhesion of the bleached control sample (4BO). Combing appears to produce a less hydrophilic fiber surface, which suggests abrasive removal of hydrophilic layers. The sample that was shampooed, conditioned, and combed shows a work of adhesion value only slightly lower than that of the uncombed samples, suggesting less of an effect from combing due to the presence of the conditioner. Structural damage Dye diffusion. Chemical and structural modifications due to bleaching were found to W (mN/m) 11o lOO 90 80 70 ß ß 4BO 4B1 T 4B2 4B3 4B4 Treament Figure 14. Work of adhesion for grooming sequences on hair bleached four hours in H202.