Comparison between the measured mass-metallicity data points of GCs in Hydra/Centaurus, and the default version of the self-enrichment model by Bailin & Harris. The Y axis is the current mass of the GCs. The black curve shows the self-enrichment model with β = 2 and f_⋆ =0.3. The blue and red solid curves are the result of the combination between self-enrichment and pre-enrichment. The dashed lines represent the scatter in colour of the points used in Fig. 5, converted into metallicity. The straight lines are the linear fits from Fig. 7.