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j. Soc. Cosmet. Chem., 48, 93-105 (March/April 1997) Spatially resolved cornbinD analysis j. JACHOWICZ and M. HELIOFF, International Specialty Products, Wayne, NJ 07470. Accepted for publication June 1, 1997, Synopsis A new technique, termed spatially resolved combing analysis, was employed to study the conditioning prop- erties of a cationic polymer on various types of hair. In this method, special frames are employed that allow the application of a treatment to selected areas of the fibers, while shielding the remaining portions as internal reference sections. The combing traces of hair treated in such a way, obtained by using a Diastron tensile tester, show positive or negative peaks depending on whether the treatment results in an increase or a decrease of friction against the hair surface. The method has higher sensitivity than previously employed procedures that involved the measurements of hair before and after conditioning of the whole tress. The conditioning of polyquaternium-11 was evaluated on untreated, Caucasian brown hair as well as on fibers damaged by oxidative dyeing, bleaching, bleaching/dyeing, and perming. It has been shown that the conditioning effect depends on the type of hair modification. The effect of the polymer on untreated hair is relatively small and becomes apparent only after multiple shampooing, which roughens the untreated sections of hair. For dyed hair, which exhibits three to four times higher combing forces than the reference virgin hair, the adsorbed polyquaternium-11 reduces the combing forces to the level of untreated hair. The conditioning layer of the polymer can be removed from dyed hair by one to two shampooings. The polymer showed higher substantivity for bleached and perreed hair, with the conditioning effect persisting after multiple shampooings. INTRODUCTION Quantitative combing measurements are widely employed in the evaluation of hair care products. The technique was first described by Newman eta/. (1), and further developed by Tolgyesi eta/. (2) and Garcia and Diaz (3). Detailed discussion of various factors affecting the quantitative combing analysis of hair, including the application of two combs, was reported by Kamath and Weigmann (4). In all these publications the procedure consisted of passing a comb through a hair assembly in the form of a tress and measuring the forces as a function of distance. To evaluate the conditioning effect, the measurements had to be performed first on untreated fibers, and then, after the treat- ment, on modified hair. The error of combing work data was +20% and +50% for wet and dry hair evaluations, respectively. This relatively high error, related to variability in relative placement or entanglement of the fibers in a tress, precludes the possibility of unequivocal detection of small changes in the frictional properties of hair. This report presents a new approach to combing measurements, termed spatia//y resolved combing analysis, which consists of applying the modifying treatments to only selected areas on 93