Published online by Cambridge University Press: 10 February 2011
Coating of solid surfaces with uniform, thin liquid films occurs in many industrial processes. A common process consists of spraying some liquids or emulsions on a freshly created solid surface. In this context, we have investigated the impact of a single droplet of various emulsions and surface-active solutions on a solid substrate using a high frequency fluorescent visualization technique (1 picture every 0.25 ms). Whatever the materials in presence, the drop spreads and then retracts under the action of inertia and capillarity respectively. Inertia induces spreading and generates a peripheral rim which is unstable to fingering. Then contact line instabilities appear under the form of festoons with pure liquids which are damped with surface-active solutions and amplified with emulsions. When the adsorption kinetics of the surfactant is slow, the equilibrium surface tension is not restored during the duration of the experiment and the drop can bounce back.