Phase-polarisation data for increasingly larger samples of members of the Koronis dynamical family. Top panels: phasepolarisation data for the two asteroids (158) Koronis and (208) Lacrimosa. In both cases, the data do not allow us to compute a phase-polarisation curve according to our criteria explained in Sect. 3. Bottom-left panel: plotted phase-polarisation curve, obtained by merging the polarimetric data for (158) Koronis and (208) Lacrimosa, as well as some data for a small number of additional Koronis family members. Bottom-right panel: slightly different phase-polarisation curve obtained by adding a fairly large number of Very Large Telescope (VLT) data, obtained by Cellino et al. (2010) for a sample of small members of the Koronis and Karin families (the latter being a sub-family of that of Koronis, see text), to the measurements used to produce the curve shown in the previous panel.