Evaporation leads to concentration and surface tension gradients that drive flow up the plate.
An experimental study indicates that the thin film is subject to two distinct instabilities. The second instability was evident only when the plate was nearly vertical, and was characterized by transverse waves propagating up the plate. We demonstrate that the observed longitudinal rolls are driven by the combined influence of surface deformations and alcohol concentration gradients. We develop stability criteria for the film which are in qualitative agreement with our experimental observations. Our analysis yields an equation for the shape of the interface which is solved numerically and reproduces the salient features of the experimental flows, including the slow lateral drift and merger of the ridges.