Overlay of the settling velocity-mass relation and the outcome of laboratory experiments on dust collisions. The red and blue lines show the settling velocity versus the grain mass in the radiative part of the atmosphere during phase II for the Σ10 and Σ4 case, respectively. For the Σ10 case, these are the same 12 structures shown in the right panel of Fig. 12. The black lines show in a simplified way the outcome of collision experiments (Güttler et al. 2010) in the collision velocity-grain mass plane. The actual outcome also depends on the grain porosity and the mass ratio of the projectile and target.