268 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Figure lb. Photograph of hair sample holder with one hair mounted and top plate in place. Note that the holder is mounted in the GP-1R with the hair fiber in a horizontal position. Also, because of the magnetic tape on the bottom plate, the use of the four fasteners is optional. them one at a time, as stated above, from 0 ø to 75 ø, and averaging the results. The time for a single scan was 75 seconds. All SAC experiments were run with the hair fibers at an incident angle of 30 ø and oriented so that the direction of incident light was toward the tip of the hair [RER orientation (3)]. All experiments involving commercial conditioner were run at an incident angle of 45 ø in order to compare the results to previous measurements run on the Brice-Phoenix photometer, an instrument on which scans from 0 ø to 75 ø could only be run at 45 ø incidence. In the Brice-Phoenix experiments, for an RER orientation at 45 ø incidence, reflection from the back walls of hair fibers was found to interfere with the estimate of diffuse scattering at 75 ø (1,3). All the former 45 ø measurements on the Brice-Phoenix instru- ment, and also the current GP-1R 45 ø measurements, were therefore run with the hair fibers in an REL orientation.

SURFACTANT INTERACTIONS 269 The output from the GP-1R was sent to a Bascom-Turner 3120T electronic recorder (Bascom-Turner Instruments, Norwood, MA) that digitized the 75 ø scan into 500 points. These points were then sent to an IBM PC computer for processing. MEASUREMENT OF SHINE All shine values were calculated from light-scattering parameters, using the previously developed expression (1), L = S/DW(V2) (Eq. 1) where L is shine, or luster, W(V2) is the width of the spectral peak at half height, and S and D are the integrated specular and diffuse reflectances, respectively. A detailed description of the foregoing terms along with a discussion of hair shine can be found in the previous work (1). All shine values calculated using equation 1 were averages taken from a minimum of three tress measurements. Since each tress measurement was, in turn, averaged over 21 hairs, each shine value represents an average taken from at least 63 hairs. STATISTICAL TREATMENT OF DATA All light-scattering and subjective evaluations performed in the half-head tests were analyzed using a sign test. All measured shine values of treated tresses and all deposition values from radiotracer experiments were analyzed by means of a one-way analysis of variance (ANOVA) test. In the following tables, measured values of tresses and swatches not significantly dif- ferent from each other (at a 95% level of confidence) are connected by vertical lines. RESULTS AND DISCUSSION STEARALKONIUM CHLORIDE/DETERGENT TRESS EXPERIMENTS Table I lists the shine values resulting from a large series of SAC/detergent tress experiments. Those tresses treated only with SODS (clean hair) had the highest shine values and thus the greatest shine. Clean tresses treated with SAC, on the other hand, were found to have lowered shine values. This dulling is a result of deposition of SAC particles on the surface of the hair (1,4,5). An attempt was made to clean SAC-treated tresses with 20% TEALS. Since previous experiments in which clean tresses were washed with TEALS resulted in shine values similar to those obtained with SODS, it was expected that removal of some of the deposited conditioner by the TEALS detergent would cause the measured shine values to increase toward that of clean hair. In Table I it is seen that the shine values did not, in fact, increase upon washing SAC-treated tresses with TEALS but, rather, decreased by a further 42%. As was the case with interactions of substantive shampoo ingredients (1), such a decrease in shine implies that the anionic TEALS detergent was not very effective in cleaning SAC from the hair surface, but instead interacted with the deposited cationic conditioner