text: polymers which only result in ﬁngers without side-branches [75] or ﬁelds of droplets left behind 
  
  [18]. 
  
  A quantitative analysis shows that the mean number of ﬁngers depends only very weakly on the av- 
  
  erage concentration of the nanoparticles ρav 
  n ; only the mean ﬁnger width increases with increasing 
  
  concentration. However, decreasing the mobility (i.e., decreasing the diffusivity of the particles) 
  
  leads to a much denser ﬁnger pattern and also causes the front instability to appear at an earlier 
  
  stage, i.e., when the front instability is in its initial linear regime, it has a higher growth rate and a 
  
  smaller characteristic wavelength (cf. Fig. 2(c) and (d)). Decreasing the effective chemical poten- 
  
  tial (increasing its absolute value) has a similar but less strong effect. For details see [41]. These 
  
  ﬁndings lead to the conclusion that the determining factor for the front instability is the ratio of 
  
  the time-scales of the different transport processes. In particular, the front becomes more unstable 
  
  when the velocity of the dewetting front increases as compared to the mean diffusion velocity of 