Growth and bouncing of a water ice grain with a₀ = 0.2 µm in our standard disc model (see Sect. 3.3) for two different distances. Our model (solid lines) uses Eq. (25), while the model from Garcia (2018, dotted lines) uses the Υ_d given by Shimaki & Arakawa (2012a). The dashed and dot-dashed lines show the impact of multiplying Vstick from Eq. (14) by 10 or 100. The light tan polygons trace the parameter space probed in experiments by Weidling et al. (2012) and Kothe et al. (2013). The grey shaded area marks the range of filling factors for which bouncing is not effective (see text).