where γ is the liquid-gas surface tension and f ( h ) is a local free energy term that describes the wettability of the surface. Since µ corresponds to a chemical potential, the term µh may either bias the system towards the liquid or towards the gas state. The variation of F w.r.t. h gives the pressure. It contains the curvature (Laplace) pressure − γ Δ h and the disjoining pressure Π( h ) = − ∂$_{h}$f ( h ) . Many different forms for the latter are in use (see, e.g., Refs. [4, 8, 63, 70–73]). For the present system a thin film description using Eq. (1) is not appropriate because the nanopar- ticles are not taken into account. However, under certain conditions one can augment equation (1) for the evolution of the film thickness by coupling it to an equation for the evolution of the mean particle concentration. The resulting model is able to describe the behaviour of an evaporating so- lution on the meso- and macroscale. Such an approach is briefly discussed below in Section III C. We should expect such a model to describe the mesoscopic dewetting front discussed above. How- ever, the theory is less suited to a description of the dewetting dynamics of the ultrathin postcursor film. The dewetting of the ultrathin film of highly concentrated suspension may be described by a dis- crete stochastic model such as, for instance, a kinetic Monte Carlo (KMC) model based solely on evaporation/condensation dynamics of the solvent and diffusion of the solute [35, 39, 41]. The va- lidity of this strong assumption regarding the relevant transport processes can be confirmed from an estimate based on Eq. (1): The pressure p = δF/δh drives convection and evaporation. The convective mobility is proportional to h $^{3}$, i.e., it is large for thick films but decreases strongly with reduced film thickness. The evaporative mobility, however, is a constant, implying that evapora- tion will dominate below a certain (cross-over) thickness. For the parameter values of Ref. [57] and a small contact angle ( ≈ 0 . 01 ), the cross-over thickness is in the range of 1-5 nanometers. This estimate justifies the neglect of convective transport in a description of the postcursor film and may explain why one has such good agreement between the experimentally observed patterns and the patterns obtained from a purely two-dimensional (single layer) kinetic Monte Carlo model [35]. We introduce the KMC model below in Section III A. In several respects, however, the kinetic Monte Carlo model is rather simplistic, limiting its po- tential applications. For instance, the thermodynamic chemical potential as well as any wetting interaction of the solvent with the substrate are collected in a single parameter – an effective chem- ical potential. This implies that any influence of a disjoining pressure is ‘smeared out’ over the whole system and that no distinction between the short- and the long-range parts of the disjoining pressure is possible. It is furthermore based on the assumption that evaporation/condensation is 8