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

270 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table I SAC Tress Experiments • Treatment No. tresses treated Shine 2 SODS 18 1.72 (0.23) SAC 3 1.15 (0.07) SAC/TEALS 6 0.67 (0.12) SAC/SODS 18 1.47 (0.27) SAC/SDES-2 3 1.53 (0.07) Shine values connected by a vertical line were not significantly different. Numbers in parentheses are standard deviations. to form an insoluble complex that was more dulling to the hair than the original deposited soil. That such a complex was actually being formed was confirmed by dye-staining exper- iments, such as were performed in reference 2, in which it was shown that the anionic dye, Red 80, could not stain hair or wool swatches treated with SAC and then washed with TEALS. Since the light-scattering results showed that SAC still remained on the surface of these swatches, these results indicate that the cationic SAC was unavailable for binding to Red 80 because of complexation with lauryl sulfate anion. The above type of complex formation occurs on the surface of hair because of the insolubility of the SAC:lauryl sulfate interaction product. It was therefore reasoned in reference 2 that changing the chain length of the detergent might render the interaction product more soluble such a detergent could then effectively clean the SAC from the hair surface rather than form an insoluble complex with it. This reasoning is shown to be correct by the results in Table I. The shine numbers of SAC-treated tresses washed with the shorter-chain surfactants SODS (C8 and C10 mixture) and SDES-2 were observed to increase in value, becoming almost as great as the value for clean hair. This indicates that these two detergents, unlike TEALS, were effective in removing SAC from the hair surface. We therefore conclude that, as a result of shortening the detergent chain length, SODS and SDES-2 did not form insoluble complexes with SAC, thus leading to improved cleaning of conditioner. CONDITIONER/DETERGENT RADIOTRACER EXPERIMENTS In order to test the above light-scattering conclusions, and also to compare the shine values in Table I to relative conditioner/detergent depositions, a series of radiotracer experiments was run measuring deposition on wool swatches after various SAC and detergent treatments. The results of these measurements are tabulated in Table II. Note that ALS (ammonium lauryl sulfate) rather than TEALS was employed in the measurements in Table II. This was considered to be an acceptable substitute, since both TEALS and ALS produced the same light-scattering results with SAC. The data in Table II show that, as was concluded above, SDES-2 is superior to lauryl sulfate detergents in cleaning SAC deposits. After washing SAC-treated swatches, ALS removed only 31% of the deposited conditioner vs 62% for SDES-2. In addition, it is