Optimisation of the Wax and Oil Phases in a Conventional Lipstick Using Mixture Design

Lipstick is essentially a mixture of oils, waxes and pastes. The type and ratio of ingredients in the lipstick base determine the type and intensity of interactions, which directly affect the quality of lipstick. Fundamentally, a lipstick must have sufficient stick strength to withstand the force during application, but it should also have appropriate ‘pay off’ characteristics. The traditional empirical approach may be inefficient in the development of lipsticks, because of the number of formulation variables and the two competing requirements.

The results of this study have revealed the quantitative relationship between the hardness of a lipstick (expressed as its breaking and softening point) and its ‘glide’ performance. The use of the Mixture Design approach has made it possible to effectively select the samples with the best overall characteristics, on the basis of limited but focused experimental work.