Zn I line at 4810.5 Å for three pairs of stars with similar stellar parameters but very different [Zn/Fe] values: a) and b) show stars with [Fe/H] ≈ −1.8; c) and d) stars with [Fe/H] ≈ −1.5; e) and f) stars with [Fe/H] ≈ −1.1. In each case, the spectrum is shown with black crosses, while the best fit is shown with a red solid line, and blue dashed lines show upper and lower errorbars (including error due to stellar parameters). The green solid line shows the case where there is no Zn present.