210 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS three tresses was then given a series of different grooming treatments: (i) One tress in each set was shampooed using a 15% solution of sodium lauryl ether sulphate, rinsed and towel dried. (ii) The second tress was treated as above but in addition was wet-combed before drying. (iii) For the third tress a quarternary ammonium based conditioner was applied and worked through the hair before the wet-combing, and then rinsed out before drying. All tresses were allowed to dry naturally in air before the next grooming treatment was given. Each tress was groomed a total of 50 times, and initially and after each sequence of 10 groomings the condition of the cuticle was assessed. 25 hair fibres were examined to obtain a cuticle count and 50 for the damage count. This number was found to be sufficient to obtain reproducible results. The cuticle counts obtained were expressed as a percentage of the initial count, and both counts were plotted against the number of grooming treatments given. "ON-HEAD" EXPERIMENT The subject for these experiments was a male Caucasian with hair up to 25 cm long and in good condition. The subject's hair was groomed every one or two days in a given manner for a reasonable period of time and then assessed for cuticle damage by determining the damage count at the hair ends as described above. The selection of hair fibres for assessment and their length were standardized to minimize any extraneous influences. In all cases 100 hair fibres were examined at a distance of 20 cm from their root ends to assess the damage counts. Two types of trials were carried out, one in which half the head was groomed in one way and half in another way, and the second in which the whole head was groomed in a particular manner, assessed, and then the grooming technique altered and again assessed: (i) For a period of three months the whole head of hair was given a standard grooming treatment using a conditioner, i.e., the hair was shampooed, rinsed, conditioner applied, the knots combed out, the conditioner rinsed off, and the hair dried in a manner which did not re-introduce knots. The damage was then assessed at the hair ends. The hair was next groomed in a similar manner but without a conditioner, and using a brush after towel drying to remove the knots. After 4 weeks of this grooming the damage was again assessed. Finally grooming reverted to the original technique for a further 6 months when the damage was again assessed. (ii) The whole head of hair was shampooed and towel dried. Then one half was combed and the other half brushed to remove the knots. No conditioner was used. After 4 weeks of this treatment the cuticle damage at the fibre ends was assessed for each half. RESULTS AND DISCUSSION Figure 5 gives the cuticle count results with progressive grooming from the tress experiments and Figure 6 gives the damage count results obtained. The results were

EFFECT OF GROOMING ON HAIR CUTICLE 211 HAI__R 1_. I _K E__Y [ ß I • SHAMPOO, RINSE, TOWEL DRY .•.,•'• /• ---..•..--- AS ABOVE, PLUS WET COMB IUU -r•'•-• • •-- AS ABOVE• PLUS WET COMB I •• I WITH CONDITIONER • '• • -I.03 ,o- •. - 1.19 o 1o o NUMBER OF GROOMINGS lOO 80 6o HAIR 2. ß ß ,• 0 Z• "" ß ' •"- -.407 0 10 20 30 40 50 NUMBER OF GROOMINGS Figure 5. Cross-sectional cuticle counts with progressive grooming (tresses). fitted to straight lines by linear regression, the slope of the lines giving an indication of the relative rates of damage incurred with grooming. Only one set of results is plotted for the damage counts as the second hair sample showed minimal damage when assessed in this way. This is probably due to this hair's high initial cuticle count which meant that even though some cuticle had been removed, as evidenced by the cuticle count, enough remained so that there were virtually no areas of the hair's surface that were completely devoid of cuticle. This gave D as a virtually constant zero value for this hair sample. Table I gives the damage count results obtained from the "on-head" grooming trials. The tress experiment results clearly showed that the normal grooming of hair can be responsible for the complete removal of the cuticle and the subsequent splitting of the cortex. At the beginning of the tress experiments both samples of hair were in good condition. The hair fibres were completely covered by cuticle right to their tips, as evidenced by the zero initial damage counts. By the conclusion of the experiment many