In most dewetting studies a thin polymer film is spin-cast onto a substrate. Even in the case of  the film does not dewet immediately if it is in a metastable state, e.g. if the temperature is below the glass transition temperature of the polymer. Annealing such a metastable film above its glass transition temperature increases the mobility of the polymer-chain molecules and dewetting takes place.
The process of dewetting occurs by the nucleation and growth of randomly formed holes, which coalesce to form a network of filaments, before breaking into droplets.  When starting from a continuous film, an irregular pattern of droplets is formed. The droplet size and droplet spacing may vary over several orders of magnitude, since the dewetting starts from randomly formed holes in the film. There is no spatial correlation between the dry patches that develop. These dry patches grow and the material is accumulated in the rim surrounding the growing hole. In the case where the initially homogeneous film is thin (in the range of 100 nm), a polygon network of connected strings of material is formed, like a Voronoi pattern of polygons. These strings then can break up into droplets, a process which is known as the Plateau-Rayleigh instability. At other film thicknesses, other complicated patterns of droplets on the substrate can be observed, which stem from a fingering instability of the growing rim around the dry patch.