An emulsion can be broken down (i.e. the liquids separated) by factors such as mechanical manipulation (as in a milk churn), chemical effects (as when milk is curdled by the addition of vinegar), and time.
An emulsifier is a substance which aids the formation of an emulsion. Often listed as a food additive, it usually works by thickening the mixture. Another type of emulsifier is detergent, which will bind to both oil and water, thus holding microscopic oil droplets in suspension. This principle is exploited in washing-up liquid to remove grease from plates, etc.
Emulsification' is to emulsify, to form an emulsion.
An emulsion paint (often abbreviated to emulsion) is a water-based paint commonly used for painting indoor surfaces. Emulsion paints are also known as latex paints. It is so called because the polymer is formed through an emulsion polymerization whereby the monomers were emsulified in a water continuous phase. The polymer itself is not soluble in water and hence the paint is water resistant after it has dried. Residual surfactants in the paint as well as hydrolytic effects with some polymers cause the paint to still be susceptible to softening and, over time, degradation by water.