text: is similar to the size of the nanoparticles. At a certain distance from the macroscopic front, the 
  
  ultrathin ﬁlm starts to evolve a locally isotropic pattern of holes. The holes themselves grow in an 
  
  unstable manner resulting in an array of isotropically branched structures as shown, e.g., above in 
  
  Fig. 1. This indicates that at least some of the patterns described in the literature may have arisen 
  
  from processes in similar ultrathin ‘postcursor’ ﬁlms. 
  
  The existence of the ultrathin ‘postcursor’ ﬁlm is an experimental ﬁnding that can be drawn on 
  
  when choosing a theoretical approach to account for the pattern formation (see below). Note how- 
  
  ever, that at the moment there exists no explanation for its existence. A possible hypothesis is 
  
  that the substrate strongly attracts the nanoparticles. As a result they form a dense suspension 
  
  layer having a thickness roughly equal to the diameter of the nanoparticles. The observed meso- 
  
  scopic dewetting front then actually correspond to an autophobic dewetting of a low concentration 
  
  suspension from the higher concentration suspension on the surface of the substrate. 