Chapter 12: Spreading and Drying of Drops and Art

Drops of complex fluids (suspensions or solutions of macromolecules) are present in art at different levels. Specific painting techniques entitled “splatter painting” or “drip painting” involve drops or threads of paint, respectively, splashing or streaming from a brush to form drops on the substrate. These techniques lead to specific patterns and morphologies that fluid mechanics can qualitatively and quantitatively explain. In particular, watercolour paintings where water-based inks are traditionally deposited over porous and absorbent papers bring additional complexity that lies in the spreading, imbibition and drying processes. In the first part of this chapter patterns encountered in paintings are presented and associated with physical mechanisms. In this way model systems are used to explain and characterise the physical phenomena. This section particularly shows the point of view of a visual artist and that of scientists. In the second part, sessile drops of complex liquids are considered. The drying process is a way to explore physical processes that emerge during the ageing process of paint layers. In particular, the drying of sessile drops captures some mechanical instabilities such as cracking or wrinkling and plays the role of a “small lab” to highlight particular alterations in paintings.