4. Formulation scans

4.1 Principle of formulation sweep

To modify the formulation of a water-oil-surfactant system in a controlled way, the one-dimensional sweep method is used. This involves preparing a series of identical water-oil-surfactant mixtures, with the exception of one of the formulation variables, known as the sweep variable . Generally, the composition is chosen so that the representative point of the system is located in the middle of the polyphasic zone of the Winsor diagram, i.e. with a few percent of surfactant (0.5 to 5%) and equal volumes of water and oil (figure 3 ). The sweep variable can be of any type; for convenience,...