The velocity-dependence of the dynamic contact angle is studied experimentally for a series of water-glycerol solutions having viscosities ranging from 1.5 to 672 mPa s. The results are interpreted through a theory of dynamic wetting as an interface disappearance-formation process, with the goal to analyse the dominant microscopic mechanism by which the interface formation occurs. As is shown, an assumption that this mechanism is diffusive in nature allows one to adequately describe the whole set of experimental data. Some estimates for the phenomenological parameters of the model are obtained.