Emulsifier works with two incompatible liquids. If one of them is evenly dispersed into extremely fine droplets in the other liquid, an emulsion is formed. For example, stirring oil and water can make the oil into small oil droplets that are evenly dispersed in water. However, this system is very unstable and can be layered after a short period of time. To obtain a stable emulsion, emulsifiers must be added, most of which are surface active substances. The strongly polar groups with affinity for water in the composition of surface active substances are oriented towards water, while the weakly polar oleophilic groups are oriented towards oil. In this way, a protective film with a certain mechanical strength is formed around the oil or water droplets, which hinders the mutual bonding and aggregation of dispersed oil or water droplets and makes the emulsion more stable. The process of forming a stable emulsion by adding surface active substances is called emulsification.