SENSITIVE PROBE OF HAIR SURFACE 223 three tresses mounted for each treatment. Figure 1 shows a photograph of the frame used for mounting tresses for subjective comparisons. Each tress is clamped at the root end, stretched over the cylinder, and secured at the tip. This setup insures that all tresses are oriented in the same manner toward the viewing light and also minimizes orientation differences among the individual hairs comprising the tresses. Tresses were viewed under two lamps, each of which contained two cylindrical, 60-watt tungsten bulbs. The lamps were placed side by side so that all four bulbs were in a single row approximately ten inches above the tresses. This configuration maximizes the chances that each tress receives the same amount of light. Figure 1. Photograph of frame used for subjective shine assessments. Tresses are clamped at the root end and stretched over the cylinder. A wooden block is then placed over the tip end and held secure by wedging a small piece of flexible tubing between the frame and the block.

224 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Following mounting, tresses were evaluated by sixteen to twenty panelists, each of whom was asked to rank the tresses in order of relative shine. After evaluation, tress positions were interchanged and a new set of evaluations performed. This was done in order to minimize any positional biases. The data from the above rankings were evaluated statistically by the Friedman test (5). This is a non-parametric test and has several advantages over the corresponding para- metric methods since it does not require a normal distribution and makes no assump- tions concerning variance of the data. GONIOPHOTOMETRIC MEASUREMENTS The bulk of the goniophotometric measurements were performed using a Brice-Phoenix light-scattering photometer (Virtis Co., Gardiner, NY), modified by attaching a re- corder motor to the graduated disc in order to automate scanning of receiving angles. Subsequent to the research described in this paper, a Murakami GP-1R automatic goniophotomer was purchased (Hunter Associates Laboratory, Inc., Reston, VA). This instrument is not subject to the scanning limitations experienced with the Brice- Phoenix photometer. The sample light-scattering curve presented in Figure 2 was produced with the GP-1R photometer. In order to maximize the accuracy of the diffuse scattering measurement (D in Figure 2), polarizers having directions of polarization perpendicular to the plane of incidence were 0 15 30 45 60 75 SCATTERING ANGLE Figure 2. A typical light-scattering curve for a virgin Oriental hair. D is the diffuse reflectance and is calculated by measuring the area under the straight line connecting the light intensities at 0 and 75 degrees. S is the specular reflectance, and is the total area under the curve minus the diffuse region. W is the width of the curve at half height.