Formulation and characterization of W/O/W multiple emulsions of calcium thioglycolate

Several water-in-oil in water multiple emulsions carrying calcium thioglyco late in the inner aqueous phase were prepared as models for depilatory prod ucts. Rheology steady-state flow experiments revealed the multiple systems to be adequately stable after 3-month storage. The effective multiplicity o f the emulsions was assessed by optical microscopy and confirmed by thiogly colic acid release experiments. The stability of thioglycolic acid against oxidative degradation at 25 degreesC was far higher in the W/O/W emulsion t han in an O/W reference emulsion, while at 45 degreesC the degradation rate was quite similar in both systems.