Ice plays an important role in many naturally occurring phenomena. For example, most rainfall in temperate climates is triggered by the nucleation of ice around μm-sized particles in atmospheric clouds. Another reason to be interested in ice is that thin supported ice films provide excellent model systems for studying the interaction of water with solid surfaces. Despite the importance of water-solid interactions for catalysis, corrosion, water purification and fuel cells, even the basics of this interaction are poorly understood. In fact, the best theoretical models often fail to predict even the simplest phenomena. A fundamental question, for example, is whether water/ice wets a given substrate, i.e., whether the substrate is covered up by a uniformly thick water/ice film. (In the case of non-wetting an ice film would break up into separate three-dimensional (3D) crystallites of varying height, exposing the substrate.)