This review is aimed at presenting the evaporation of macroscopic sessile droplets on inert substrates in normal atmosphere in simple cases, as a basis for more complex analyses.

The dynamics of evaporation of wetting droplets is investigated experimentally in an extended range of drop sizes to provide trends relevant for a theoretical analysis. A model is proposed, which generalizes Tanner's law in the presence of evaporation. A qualitative agreement is obtained, which represents a first step toward the solution of a very old, complex problem.

The spontaneous spreading of the 5CB nematic liquid crystal on solid substrates has been extensively studied in the last years both at the microscopic(1-4) and macroscopic(5-6) scales. The remarkable feature at the microscopic scale is the presence of a discontinuity in the thickness profile of the films. On the other hand, the spreading dynamics of macroscopic drops is quite specific. The drop first spreads like a simple liquid, and then progressively faster, while a remarkable bell-shaped profile develops at the bottom.(5-6) How the behaviors at the various scales are linked is an open question. Any answer requires reconsidering these wetting experiments deeper into the context of nematic films. More specifically, the anchoring of molecules at the interfaces(7-8) and the competition between nematic elasticity(9) and anchoring(10) must be discussed quantitatively. For the thinnest films, the problem proves to be more complex than expected and contradictory data are found in the literature. Therefore, we decided to complete our previous studies with further experiments using another compound of the cyanobiphenyls series, the 6CB in the nematic phase, and also on liquid substrates, water and glycerol. These new data confirm that the description of the thinnest nematic films is not yet fully understood.

The evaporation of wetting drops deposited on a substrate at thermal equilibrium under normal atmosphere is discussed. The evaporation rate appears to be controlled by the stationary diffusion of vapour molecules in the gas phase. Experiments with alkanes and water drops are fairly well accounted for by an isothermal model, taking into account the specific properties of thin films.

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