The aim of this work was to apply an experimental design to formulate a stable depilatory cream at ambient temperature. A preliminary study was performed to optimize the most accurate operating parameters, which are then used for the determination of the rheological properties. Long-term stability of the emulsion formulations was investigated to obtain the optimal region of each factor. An experimental design using response surface modelling was then applied and emulsion stability was estimated by introducing new characteristic parameters correlated with the experimental results. An optimal region characterized with high stability was found and further explored to verify the effectiveness and tolerance of depilation. As part of the optimized process, the main effects of the formulation ingredients were also investigated.

The aim of this work relates to the optimization of a cold formulation of a depilatory emulsion containing thioglycolate of calcium, which presents the same characteristics as a reference product. To lead to this objective, a cubic simplex method was used. A preliminary formulation was preformed to evaluate the influence of each factor on the process formulation. The depilatory creams carried out present a rheological behaviour described by the model of Hershell-Bulkely, whose parameters are considered as responses of the optimizing system. This strategy allows both reducing and optimizing the number of experiments. The rheological measurements and the tests of stability showed that the use of an emulsifying polymer led to obtain a stable depilatory cream with a good effectiveness at a strong pH value.

No abstract