Experimental evidence is given for the mechanism of film formation from industrial waterborne latices using Inverse-Micro-Raman-Spectroscopy (IMRS). In the vertical direction of the,film drying is gas-side controlled, indicated by uniform water concentration profiles. In the horizontal direction inhomogeneous drying resulting from a horizontal mass flux toward the edge of the film and the formation of a drying front are observed. The completeness of film formation is tested by so-called IMRS redispersion experiments. For hard lances (T-experiment similar or equal to T-mff) particle deformation is incomplete and the final coating-although transparent and optically clear-is a porous structure with a network of surfactant material located at the particle interfaces. The use of a film forming aid lowers the polymer's minimum film formation temperature (T-mff) and facilitates particle deformation and polymer interdiffusion. The result is a nonporous film structure where individual particles and a network of surfactant material are no longer observed. IMRS redispersion experiments are compared with pictures of the final coating surface obtained from atomic force microscopy (AFM).