Abundance corrections for the Na i line at 8194 Å between different models, and specifically, from left to right: 3D NLTE to 1D LTE, 3D NLTE to 1D NLTE, 1D NLTE to 1D LTE, and 3D NLTE to 3D LTE, colour-coded as their [Fe/H]. The datapoints are computed at [Na/Fe]= −0.5 to +0.5 for the dwarfs, and +1.0 for the giants, in steps of 0.5 dex and, for the 1D models, at a v_mic = 1.0 km s⁻¹.