Influence of salt content on crack patterns formed through colloidal suspension desiccation

We analyze the influence of physicochemical properties on crack patterns formed by desiccation of a colloidal suspension, in the simple geometry of an isolated drop deposited on a flat surface. Depending on the suspension salinity, different types of crack patterns are observed: at low salinities a regular pattern of radial cracks develops all around the drop edge; at intermediate salinities, disordered patterns form, while at large salinities a unique circular crack appears. These behaviors are controlled by the evolution of the drop shape, that also depends on the suspension salt content. At intermediate salinities, large drop shape distortions appear that can be interpreted as a buckling instability. [S1063-651X(99)08903-5].