Which Controls Wetting? Contact Line versus Interfacial Area: Simple Experiments on Capillary Rise

Working equations that describe wetting phenomena can be derived in a variety of ways starting from capillary forces, Laplace pressure, or solid surface energies. We examined the relative importance of the contact line and interfacial areas in the capillary rise inside small diameter glass tubes. A series of simple experiments demonstrate that this wetting phenomenon is controlled by interactions in the vicinity of the contact line.