A surfactant is a compound which lowers the surface tension of a liquid, increasing the contact between the liquid and another substance. There are a wide variety of surfactants, which work with oil, water, and an assortment of other liquids. Many companies manufacture a range of surfactants for various purposes, ranging from soaps to inks. You may also hear a surfactant referred to as a “wetting agent.”

The term is a compound of “surface acting agent,” referring to the fact that a surfactant interacts with the surface of a liquid to change its properties. Surfactants work through a process known as “adsorption,” which means that they accrete on the surface of a liquid, creating a film which reduces its surface tension.

One of the most famous surfactants is soap, which is used to break the surface tension of water so that it can penetrate more fully. The foaming action of soap helps water get under dirt and grease on surfaces like dishes, hands, and fabrics, allowing the water to carry the dirt away. As anyone who has tried to wash without soap knows, the high surface tension of plain water makes cleaning very difficult.

Surfactants can also work as lubricants, as is the case with shaving a cream, a surfactant which makes it easier to run a razor along the skin to remove unwanted hair. Surfactants are also used in sanitizing products, anti-fogging liquids, adhesives, emulsifiers, and fabric softeners, among numerous other substances. In some cases, a surfactant may be toxic or pose a health risk, depending on the materials it contains, and it is a good idea to read labels to make sure that a surfactant is used properly.

The term “surfactant” is also used in the medical community to refer specifically to a substance secreted by the cells which line the lungs. Pulmonary surfactant makes it easier for people to breathe by reducing surface tension in the lungs. Without surfactant in the lungs, people would have trouble breathing, and their breathing would be much noisier. Many of the respiratory problems in premature infants are caused by lack of surfactant, and some rare lung diseases can also interfere with surfactant production and function.