296 JOURNAL OF COSMETIC SCIENCE o lO 6 4 2 0 water soap brilhantine D-B1 T I I CIELAB FMCi1 D-B2 D-B3 hair sample Figure 2. Average of color-difference values obtained after treatments in the dark-brown hair. Samples D-B1, D-B2, and D-B3. Treatments: water 350-40 ø C (grey bar), commercial soap (black bar), and brilliantine (white bar). Quintuplicate measurements. D65 illuminant. 10 ø viewing angle. 5 x 10-mm viewing aperture. Reference tress: dark-brown hair treated with ethyl ether/8 h. CIELAB and FMCII systems. ESTABLISHING THE LUSTER SCALE Diffuse reflectance measurements were done in black hair tress (B) samples treated as described in Methods. Color differences (DL*, DC*, DE* and DL, DC, DE) were calculated using internal (color-parameter values measured for every sample before the treatments) and external (color-parameter values measured for the tress before the treat- ments) references. All samples came from the same tress. Internal and external references were chosen based on the L*, a*, b* (CIELAB) and X, Y, Z (FMCII) values. The inter- nal reference data was chosen by taking the value closest to the average among a set of ten measurements. These values were taken from the diffuse reflectance data of each of the alcohol-treated samples of the tress. The external reference was chosen among the

MEASUREMENT OF HAIR LUSTER 297 4 Standard FMClI _L first second third fourth Figure 3. Average color-difference values obtained after sequential treatments in more damaged dark- brown hair tress. Treatments: standard and PQ7 Natura formulations. Quintuplicate measurements. D65 illuminant. 10 ø viewing angle. 5 x 10-mm viewing aperture. Reference tress: damaged dark-brown hair tress treated with ethyl ether/8 h. FMCII system. . • 3 internal reference I external reference • I I n ethcorn s+nl s+n2 s+n3 treatments Figure 4. Average color-difference values obtained after sequential treatments in black hair sample using external and internal references. Sample B3. Treatments: n (Neutrox © conditioner), ethcom (ethanol com- mercial/40 min), s + nl (]•lseve © shampoo + Neutrox©/first wash), s + n2 (]•lseve © shampoo + Neutrox©/ second wash), s + n3 (Elseve © shampoo + Neutrox©/third wash). Results of ten measurements. D65 illuminant. 10 ø viewing angle. 5 x 10-mm viewing aperture. Internal reference: ethanol PA/8 h treatment (fourth reading). External reference X = 3.27, Y = 3.32, Z = 3.23. FMCII system.