Abstract
The drying process of thin films of polymer solutions or colloidal suspensions with a pinned contact line is investigated theoretically. The time evolution of the surface shape is calculated by taking into account of the solvent evaporation, the internal flow driven by surface tension, and the gelation (or solidification) of the fluid. It is shown that the final shape of the solidified film changes from dot-type to ring-type as the initial concentration of solute increases, or the evaporation rate decreases, but this is due to a rather intricate balance of the change of the solvent evaporation rate and the change of viscosity.