Emulsions used in personal care and cosmetic formulations—both oil-in-water (O/W) and water-in-oil (W/O) types—need to satisfy a number of criteria. They must demonstrate physical stability over 2-3 years under various conditions, such as temperature variation and stress induced by vibration during transportation.
They must also maintian the proper consistency (rheology) to achieve good skin-feel, spreading and delivery of actives. Finally, the safety of the ingredient used must be assured to avoid any skin irritation or adverse effects on contact with the skin.
