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As the world is striving to become more sustainable, water consumption is considered an important area of focus, especially in those regions with limited freshwater resources. To address this issue, the personal care industry has identified faster rinsability of hair care products as a way to contribute to water preservation efforts. To understand rinsability, analysis of colloidal systems and an investigation into concentration of whole products in water is critical. However, particle size and particle migration in colloidal systems require the use of specialized optical methods. In previous research, we learned that conditioners form colloidal particles rather than true solutions during the rinsing process, and hence cannot be studied using ultraviolet-visible spectroscopy. Through this study, a Turbiscan instrument was determined to have the capability of measuring multiple light scattering given off by conditioner systems. Therefore, measurements of light scatter from a series of diluted conditioner dispersions can be used to generate a calibration curve to calculate unknown concentrations of conditioner in rinse water at different rinsing time intervals. The newly developed test method was successfully applied to determine the rinsability of various conditioner formulations on both virgin and bleached hair. The findings of our study will be presented here.

A new test method has been developed to determine surface energy of hair fibers through measurements of contact angles at two hair/liquid interfaces. By measuring changes in surface energy of the same hair fiber before and after a cosmetic treatment, effects of active ingredients and the performance of tested formulations can be evaluated.The establishment of the method is based on Fowkes theory (1,2) described with two components, a dispersive and a non-dispersive component. The non-polar liquid used in this study was diiodomethane, and the polar liquid was benzyl alcohol. A Kruss 100 Tensiometer was used to measure contact angles of hair fibers. Virgin dark brown and regular bleached hairs were treated with selected conditioner formulations. Reductions in combing forces of hair tresses before and after respective treatments were correlated with decreases in average surface energy of hair fibers obtained from the corresponding tresses.Experimental results indicate that the average surface energy of hair fibers treated with conditioners decreases and the hydrophobicity of the hair surface increases, the results correlate well with the reduction in combing forces after respective treatments. This research work provides a new methodology to evaluate/screen conditioning performance of hair care ingredients and formulations for development of better products.