Drying suspensions often leave behind complex patterns of particulates, as might
be seen in the coffee stains on a table. Here, we consider the dynamics of periodic
band or uniform solid film formation on a vertical plate suspended partially in a
drying colloidal solution. Direct observations allow us to visualize the dynamics of
band and film deposition, where both are made of multiple layers of close packed
particles. We further see that there is a transition between banding and filming when
the colloidal concentration is varied. A minimal theory of the liquid meniscus motion
along the plate reveals the dynamics of the banding and its transition to the filming
as a function of the ratio of deposition and evaporation rates. We also provide a
complementary multiphase model of colloids dissolved in the liquid, which couples
the inhomogeneous evaporation at the evolving meniscus to the fluid and particulate
flows and the transition from a dilute suspension to a porous plug. This allows us
to determine the concentration dependence of the bandwidth and the deposition rate.
Together, our findings allow for the control of drying-induced patterning as a function
of the colloidal concentration and evaporation rate.