LUSTER QUANTIFICATION OF HAIR 349 250 200 150 100 50 0 -15 2g t ,Sg untreated 1 g.----• l.Sg -5 5 15 25 35 45 55 Distance (ram) untreated Figure 13. Light distribution curves for hair treated with various amounts of ZnO. 65 Table IV Luster Parameters for Hair Treated With Various Amounts of ZnO (f8 1/3 s) Amount of ZnO Peak width: W1/2 (mm) N½ Peak intensity LRei,,3_Robbi,,• Lst .... Untreated 8.30 + 0.20 0.80 + 0.02 215 + 2 0.37 + 0.02 0.67 + 0.02 0.5 g 9.55 + 0.12 0.75 204 + 4 0.31 + 0.01 0.66 + 0.02 1.0 g 9.55 + 0.51 0.71 207 + 5 0.28 + 0.03 0.62 + 0.02 1.5 g 10.41 + 0.22 0.64 211 + 1 0.24 + 0.02 0.60 + 0.03 2.0 g 11.57 + 1.25 0.65 216 + 3 0.20 + 0.03 0.56 + 0.03 sebum-treated hair, respectively. In contrast to this, luster parameters LReic3_Ro33in s and Lstam m were found to be equal to 0.34 + 0.05 and 0.74 + 0.03 for sebum-treated hair versus 0.72 + 0.03 and 0.54 + 0.07 for untreated hair, respectively. Thus, the observed dramatic loss of gloss in sebum-treated hair is not reflected in the calculated values of Lstam m. However, LReich_Robbin s coincides very well with visual observations. SUMMARY AND CONCLUSIONS An image analysis system was employed to quantify the optical and luster properties of hair. Untreated and treated hair tresses were mounted on a cylindrical support and illuminated with a collimated polarized halogen light at an incident angle of approxi- mately 30 ø relative to the horizontal optical axis. A digital camera with a resolution of 4.0 megapixels was employed as the recording device. Data, obtained in three different

350 JOURNAL OF COSMETIC SCIENCE untreated sebum Figure 14. Images ooe untreated hair and hair treated with synthetic sebum. Amount ooe treatment was ! g ooe 5% solution per 3-gram tress. Exposure values: oe8 and !/6 s. 25O 2OO • 15o 'i .• 100 50 w i i i 0 10 2o 3o 4o 5o Distance (ram) Figure 15. Light distribution curves for untreated hair and hair treated with synthetic sebum.