Coatings of liquids on surfaces such as glass are commonly used in manufacturing processes. The stability and homogeneity of these liquid films is of course crucial to these applications. In the case of silicone oils coating glass, a rough estimate of the long-range interactions such as Van der Waals’ shows that such films should bear a uniform thickness at equilibrium: repulsive interactions should tend to a flat thick film. However, in practical situation, initially heterogeneous films never get uniform in thickness in a timely manner. As examples, defects on glass substrates lead to thickness heterogeneities that grow over time rather than heal. When starting from a collection of droplets sprayed onto a flat substrate, a nanometer-thick film first spreads around the droplets, and delays the spreading and coalescence of the droplets. The goal is to gain insights into the behavior of silicone oil on glass and to elucidate the mechanisms underlying the time evolution of such coatings. To do so, model systems will be used (plane glass or chemically-modified silicon wafers, well-characterized silicone oils), and imaging techniques such as ellipsometry or profilometry will be used, in order to measure and model the time variation of silicone oil coatings. Two cases will be particularly studied. - Time evolution of oil spread onto substrates decorated will well-controlled defects - Spreading dynamics of several droplets deposited on smooth substrates.