Soaps, Syndets and Surfactants

Sumarian clay tablets from 2500 BC found between the Tigris and Euphrates rivers document the early usage of soap. Soap, the product of a chemical reaction between natural fats and alkaline lye, has some disadvantages, especially for sensitive skin. Soap scum forms and surfactants are inactivated when used with hard water. Carbonate salts are deposited on the skin hindering the restoration of oils, which makes skin raw.

Schematic diagram of surfactants.

1 Hydrophilic part

2 Lipophilic (hydrophobic) part

Development of Syndets
Soap's disadvantages led to the search for new body cleansing substances. In the late 1950's, scientists introduced synthetically produced detergents, known as syndets. Today, syndets are used in skin-beautifying cleansing because they have distinct advantages over soap:

• Do not form insoluble soap scum
• No alkalizing, so pH can be set
• Suitable for skin with a lowered alkali reducing capacity
• Little swelling of the horny layer

The currently popular expression "syndet" comes from the syllables "syn" for synthetic and "det" from detergent. Detergents refer to cleaning agents of all kinds, including soaps and synthetic surfactants. The term "synthetic surfactant" is sometimes used as a synonym for "syndet".

Surfactants
These molecules or ions are comprised of a very water soluble (hydrophilic) part (1), the head and a fat-soluble (lipophilic) long-chained segment (2). Individual surfactants have specific properties, such a creating foam (anionic surfactants), or leaving behind a pleasant sensation on the skin (amphoteric surfactants). Most cleansing products consist of a mixture of them.

Besides active cleansing agents, the term surfactant is used to describe emulsifiers, foaming agents, solvents and other similar substances.