The common cork stopper takes advantage of the peculiar properties of the bark of the cork oak. This has very low permeability to both gases and liquids due to suberin and waxes; the cellular structure makes possible the deformation that gives a secure fit in the bottle neck.
Manuel Fortes is professor of materials science and engineering at the Instituto Superior Técnico in Lisbon, and chairman of the New Materials Committee of the Portuguese Research Council. In 1989, he shared the Gulbenkian Prize for researches on cork. His current research work is focused on cellular materials and on the topological analysis of microstructures.
* Departamento de Engenharia de Materials, Instituto Superior Técnico, Avenida Rovisco Pais, 1096 Lisboa, Portugal.