RESUMEN
BACKGROUND: The required time for hair removal by chemical depilatories has always been a concern and depends on different parameters including permeation into the hair shaft. OBJECTIVES: In an attempt to improve this process, it was decided here to investigate the possibility of decreasing depilation time of thioglycolates, widely used depilatories, using penetration enhancers. METHODS: Urea, sodium dodecyl sulfate, dimethylsulfoxide (DMSO), ethanol (75 and 96%), NaCl, and peppermint and orange oils were used as penetration enhancers, and their effect on depilatory time of thioglycolates, represented as tear resistance time (TRT) of hair shaft under a constant tensile stress, was studied. The effects of temperature and hydration on TRT were also investigated. RESULTS: Results showed that ethanol (75%), DMSO, and peppermint oil (ethanolic solution) were able to significantly reduce TRT up to two times from about 6 to 3.5 min. Other enhancers were not able to change TRT. Results also revealed that increase in temperature from 20 to 37 °C reduces TRT by about 4 times. Hydration in boiling water also reduced TRT significantly about 1.5 times. CONCLUSIONS: Present results show that it is possible to reduce depilation time by penetration enhancers. Such improvement can increase users' compliance and might provide other advantages like decreased skin irritation.