JOURNAL OF COSMETIC SCIENCE 454 feature composed of several properties such as specular refl ection, multiple refl ection, sparkle, parallelism of hair fi bers, and hair color. Up to now, hair care products have to be evaluated for their hair shine-promoting proper- ties in time- and resource-intensive panel studies by experienced panelists. Such panel studies provide only relative results, i.e., rankings of the investigated products within a study, which make the comparison of different studies with different products almost impossible. Thus, to make comparison of products across studies possible, an objective quantitative measure of hair shine is required. Furthermore, to be suitable for cosmetic development, any automated quantitative physical method of measuring hair shine has to correlate with panel assessments. This claim can only be met if all properties of hair shine are covered and integrated by an automated physical method. The authors have developed a new automated tool to quantify hair shine, which records all of the fi ve above-mentioned properties of hair shine separately in a single run. The new tool makes an approximation of automated physical assessments to panel-based rankings of hair shine feasible. This is achieved by the fi ne tuning of the physical assessments to correlate with panel assessments through individual weighting of the different properties of hair shine. MATERIAL AND METHODS HAIR Commercially available hair tresses of different ethnic origin and color were used. The tresses had a net hair weight of 4.5 g, a total length of 23 cm, and a width of 3 cm. Before application of the test products, the tresses were cleaned by wetting with cold tap water for 15 min and gently washing with a standard shampoo (50% SDS, 1% NaCl, 0.4% sodium benzoate, 0.1% citric acid, and 48.5% distilled water) for 1 min, followed by rinsing with lukewarm tap water for 2 min. To apply test products, 0.2 ml per gram of hair of the respective test products was rubbed in for 1 min, and all rinse-off products were then removed by rinsing the hair strips with lukewarm tap water for 2 min. Subse- quently the hair tresses were combed until all knots or fi ber crossings were removed. The tresses were then mounted on special carriers, taking care of the parallelism of hair fi bers, and equipped with a special slit aperture to avoid refl ections from the carrier (Figure 1B). INSTRUMENTATION FOR HAIR SHINE MEASUREMENT A newly developed recording device (denoted “opsira Shine-Box” see Figure 1A) was developed by the authors in cooperation with opsira GmbH, Weingarten, Germany, and Display Metrology & Systems, Karlsruhe, Germany. This device is able to assess multiple components of hair shine in parallel, encompassing specular and diffuse refl ection half- width of specular refl ection sparkle hair color and parallelism of hair fi bers using the software tool luca′tool developed by opsira GmbH. The core detector system of the opsira Shine-Box, the recording camera, is a state-of-the-art and high-grade CCD luminance measurement camera, called luca, with a 12-Bit grey-level dynamic. The grey-level dy- namic can be expanded by taking several measurements at different exposure times to up to 18 Bit. To reduce thermal noise and thus to improve the data quality, a thermoelectric

AUTOMATED DEVICE TO ASSESS HAIR SHINE 455 cooled CCD camera is used. A further system add-on, called luca.color, enables the mounting of up to ten arbitary different fi lters between the lens and the camera chip in a motorized fi lter wheel. The fi lter wheel can be equipped with color but also with polar- ization fi lters. In the opsira Shine-Box setup, the camera is equipped with color fi lters to be able to measure according to the CIE color-matching functions x(λ), y(λ), and z(λ) to gather the color of the hair tresses. It is also equipped with a horizontal and a vertical polarizer to separate the refl ected light coming from the hair into the polarization com- ponents. All fi lters are positioned during one measurement procedure automatically by the operating software of the opsira Shine-Box. To realize the polarization analysis it is also necessary to illuminate by polarized light. This is done by a fi xed polarizer in front of the thin and long shine illumination light source. The sparkle illumination is realized with a toroidal fl uorescence light source equipped with a motorized ring cover plate blocking 340 degrees of the light source. By the remaining and rotating aperture of 20 degrees, different incident angles to the hair tresses can be adjusted to measure the angu- lar life time and thus the sparkle. The system "opsira Shine-Box" is commercialized by opsira GmbH, Leibnizstrasse 20, D-88250 Weingarten, Germany, (www.opsira.com). RECORDING PARAMETERS Objective shine value. On illumination an individual hair either refl ects light directly on its surface (surface refl ection) or the light enters into the hair and is refl ected at the second hair surface (transmission - refl ection – transmission, TRT). The light refl ected at the fi rst hair surface retains its original optical properties (spectral composition = color, state of polarization) (3), whereas the transmitted and refl ected light changes both its spectrum (color) due to absorption effects—mostly via melanin (see Figure 2) and its state of polar- ization (depolarization inside the hair). In the newly developed device the refl ection prop- erties of hair tresses mounted on the cylindrical carrier are recorded using a horizontally polarized light source. To separate fi rst-surface from second-surface refl ection, one picture is recorded with a horizontally positioned polarization fi lter (polarized fi rst-surface com- ponent = specular) and one picture is recorded with a vertically positioned polarization fi lter (depolarized second-surface component = diffuse). Figure 1. (A) Setup of the Shine-Box with carrier. (B) Details of mounted hair tress on carrier with slit aperture.