FINGERPRINTING OF COSMETIC FORMULATIONS BY DYNAMIC ELECTROKINETIC ANDPERMEABILITY ANALYSIS .2. HAIR CONDITIONERS

Dynamic electrokinetic and permeability analysis (DEPA) was employed t o investigate complete formulations of rinse-off hair conditioners as well as several types of raw materials frequently used as active ingre dients in such compositions. Quaternary ammonium surfactants, fatty am ines, and silicone emulsions were employed as model systems. Zeta pote ntial and permeability data collected before and after the treatment o f hair plugs with 0.5% or 1% solutions of single- or multi-component s olutions, respectively, allowed the comparison of their ability to mod ify hair surface. In general, the conditioners were found to deposit l ayers of surfactants or polymers with a thickness in the range of 0.6- 3.2 mu m as calculated from the permeability data obtained for the wet fibers. The systems containing positively charged species were also s hown to reverse the surface charge of hair, while those based on neutr al, fatty acid-fatty amine complexes or hydrocarbon oil (petrolatum) d id not affect significantly the electrostatic surface characteristics. The removability of the conditioner residues was tested by consecutiv e application of a conditioner and a shampoo solution. The effectivene ss of this process was gauged by comparing the thickness of the surfac e deposits and a value of zeta potential before and after the shampoo application.