94 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS a tress rather than to the whole fiber assembly. This was accomplished by the use of special treatment frames that allowed the application of polymer, surfactant, or formu- lation solutions to selected areas of the fibers, while shielding the remaining portions as internal reference sections. The combing traces of hair (usually presented as combing force as a function of distance or position of a comb in a hair tress) treated in such a way show positive or negative peaks depending on whether the treatment results in an increase or a decrease of the lubricating properties of the hair surface. Since treated and control areas are scanned in one combing measurement, the new technique has higher sensitivity than the previously employed procedures and also allows a more graphic representation of the data. The experimental data presented in this report refer to polyquaternium-11, which is a cationic copolymer frequently employed in fixative and conditioning hair care prod- ucts. Previously, the results of qualitative analysis of conditioning attributes of cationic copolymers of vinyl pyrrolidone were reported by Murphy (5). Recently, a reference to conditioning properties of polyquaternium-ll was made by Hossel and Pfrommer (6). EXPERIMENTAL INSTRUMENTATION Spatia//y resolved combing analysis. The formulations were applied to selected areas of hair tresses by the use of a two-window treatment setup (Figure 1). It consists of two plexiglas and two silicone rubber frames. A hair tress is compressed between the rub- ber and plexiglas frames with stainless steel screws and bolts. A typical procedure consists of (a) treating the exposed sections of the fibers with an appropriate formu- lation, (b) extensive rinsing with water to remove any residues of the treatment sol- ution, and (c) opening the frame to perform the wet combing analysis of the treated tress. The combing measurements were performed by employing a Diastron miniature tensile tester with the following instrument settings: range 500 G gauge 2 G sample size 50 mm phase 1 extension 350% phase 2, 0% phase 3, 0% and phase 4, 0%. The instrument was operated by Rheopac software (revision 3.0A). The data calculations and plotting were performed by using QuattroPro for Windows or Lotus 1-2-3 for Windows spreadsheets. The combing measurements were done on wet hair (3). In all experiments hair was combed several times to remove entanglements, and then mounted in the Diastron with hair evenly distributed across the 1.25-inch length of a comb (12 teeth/inch). The combing force was continuously recorded as the tress was combed at a crosshead speed of 12 cm/min. The data were analyzed either by comparing the features of the combing curves (combing force as a function of distance) or by calculating the total combing work as an integrated value of force over the length of the tress. MATERIALS Samples of hair. Experiments were performed on dark brown hair purchased from DeMeo Brothers, New York. Hair samples were precleaned with 3% ALS solution and thor-

SPATIALLY RESOLVED COMBING ANALYSIS 95 .v Figure 1. A two-window treatment frame for treating the fibers in two sections. I I i i i i Ii i ii Untreated hair after Chermcal treatment Removal of the Exposure of the whole shampooing combing through windows treatment frame tress to conditioner measurement rinsing with water and combing measurement. treatment followed by (1) shampooing. (3) rinsing combing (2) measurement. (4) Figure 2. Experimental protocol of procedure A.