surface-active agent ( surfactant )
A substance that, when used in small quantities,
modifies the surface properties of liquids or
solids. A surface-active agent reduces surface
tension in a fluid or the interfacial tension
between two immiscible fluids, such as oil and
water. Surfactants are particularly useful in
accomplishing the wetting or penetration of solids
by aqueous liquids and serve in the manner of
detergent, emulsifying, or dispersing agents. They
are more effective than soap in certain situations
and are used by conservators for such purposes as
cleaning, wetting, and dispersing. See also: WETTING AGENT .
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