First five panels: ratios of individual reddenings in several combinations of colours as a function of the effective temperatures for all GES targets (small dots) and for WTTSp cluster members with T_eff >  4000 K (red points). Lower right panel: mean ratios of reddening values for the WTTSp cluster members in several colours (red circles), compared with the expected analogous values given for R_V = 3.1 (green plus symbols) and R_V = 5.0 (blue squares) based on the Fiorucci & Munari (2003) relations.