Mass fraction profiles of accreted Mg (left panels) and mean molecular weight gradients’ profiles (right panels) for the M06T25H-4, M08T25H-4, and M10T25H-4 models, as a function of the outer mass normalised to the total mass of the white dwarf model. The top panels correspond to case 1 (the same value for σ for all models), the bottom panels to case 2 (a different value for σ so that the μ gradients’ profiles would be the same for all models). All cases were computed with the same total accreted mass (10¹⁶ g).