Recovery of used cork stoppers

Cork is a natural cellular material. As fabricated cork stoppers for wine bottles are cylindrical with a uniform cross-sectional diameter. Upon removal from a bottle, the stopper shows a smaller and slightly non-uniform diameter. If a used cork stopper is immersed in water or water vapour at a sufficiently high temperature, the original dimensions can be recovered in a time interval of a few minutes. The kinetics of dimensional recovery in air and water (liquid and vapour) at different temperatures were experimentally determined. Water absorption is determinant of a fast recovery rate. A simple viscoelastic model is used to explain the experimental results. Since the mechanical properties are also restored, the stopper can be re-used, provided the damage due to the cork-screw used to remove the stopper is confined to its bulk.