Pattern formation in drying water films

We describe experimental observations of water films evaporating from clean mica substrates. The films break up into coexisting thick and thin regions, the boundary between them forming well-defined patterns. The dynamic patterns demonstrate characteristic features which can be related to simulations of diffusion-limited growth in isotropic two-dimensional systems. The observations are related to a model for a volatile thin film bound to a substrate by both Van der Waals and polar forces.