Change of dilution factors ξ_BVI with metallicity Z. The subset of the original solar metallicty models for which corresponding calculations with a lower metallicity have been performed are shown in red. The metal-poor models are depicted in blue. Arrows illustrate the changes in model properties induced by the change to the subsolar metallicity of Z = 0.2. To facilitate the comparison to the general ξ − T trend, all models of the original grid are included in gray.