Thin wetting films formed by spreading aqueous solutions onto a purified mercury surface yield residual thin layers after drying. The thickness of these residual layers, which had been ellipsometrically measured in a previous study, does not significantly depend on the volume of the solution injected onto the mercury that is placed in a trough. Here, we model the successive processes involved in the production of these residual layers : solution spreading, film formation, and film drying. Our model calculations showed that the volume of the wetting film and, hence, the film thickness, does not strongly depend on the volume of the injected solution. The increase in the film thickness that must correspond to an increase in the volume of the injected solution is restrained due to the formation of a Gibbs-Plateau border along the trough wall. A possibly crucial parameter in the formation of two-dimensional protein crystals, namely, the time needed for drying a film, is also calculated using our model.