Solid water-in-oil emulsions for lipstick

The lips’ mucous membranes have traditionally been protected by anhydrous cosmetic systems. These are applied on to the lips as thick films, providing a water-and wear-resistant layers, which possess elastic, film and protective properties. The preferred physical form of such products, for transport ease and application convenience, is as hot-molded (60-70°C) sticks (solid lipogels). Therefore, strong and fast moisturizing action was classically obtained through occlusivity by the layer of waxes and mineral oils. Our study investigated such cosmetic systems as w/o emulsions, which maintain the rheological characteristics and ease of application of molded lipstick, while allowing the use of high amounts of polar lipids and vegetable oils. In general, they provide emolliency and reparation properties of the hydrolipidic barrier, while aqueous solutions bring protective and water-holding capacities. The emulsified form could also allow improved activity and interaction with the superficial skin layers. Our research involved the selection of suitable emulsifiers, with high resistance to destabilization by temperature cycles and to evaporation of emulsified water.