Capillary action (sometimes capillarity, capillary motion, or wicking) is the ability of a liquid to flow in narrow spaces without the assistance of, or even in opposition to, external forces like gravity. The effect can be seen in the drawing up of liquids between the hairs of a paint-brush, in a thin tube, in porous materials such as paper and plaster, in some non-porous materials such as sand and liquefied carbon fiber, or in a cell. It occurs because of intermolecular forces between the liquid and surrounding solid surfaces. If the diameter of the tube is sufficiently small, then the combination of surface tension (which is caused by cohesion within the liquid) and adhesive forces between the liquid and container wall act to lift the liquid.

History

The first recorded observation of capillary action was by Leonardo da Vinci. A former student of Galileo, Niccolò Aggiunti (1600–1635), was said to have investigated capillary action. In 1660, capillary action was still a novelty to the Irish chemist Robert Boyle, when he reported that "some inquisitive French Men" had observed that when a capillary tube was dipped into water, the water would ascend to "some height in the Pipe". Boyle then reported an experiment in which he dipped a capillary tube into red wine and then subjected the tube to a partial vacuum. He found that the vacuum had no observable influence on the height of the liquid in the capillary, so the behavior of liquids in capillary tubes was due to some phenomenon different from that which governed mercury barometers.

Capillary Action is an American avant-rock/experimental music group formed at Oberlin College in 2004 by Philadelphia native Jonathan Pfeffer, the group's sole constant member, and active until 2012.

Capillary Action's self-described “confrontational cubist-pop” was characterized by an unusual blend of acoustic timbres; complex, constantly shifting meter; and Pfeffer’s 12-tone and Philly soul-inspired baritone vocals. The lyrics often employed autobiographical themes to critique power structures. Pfeffer cites Tropicália, Dizzee Rascal, Tim Buckley, the Batman Forever soundtrack, Need New Body, Joe Matt, the Minutemen, Converge, Ornette Coleman, and Scott Walker as major influences.

The group performed extensively across North America and Europe alongside Joe Lally, The USA Is a Monster, The Max Levine Ensemble, Už jsme doma, Lightning Bolt, Dirty Projectors, Deerhoof, Les Claypool, Rhys Chatham, Shudder to Think, and Dos, among others.

In 2009, Boston Phoenix named Capillary Action the Best New Band from New York, likening the group to "Both Elvises in a serious Burt Bachawreck with the Mothers of Invention".[3]