Ratio of the [Na/Fe] spreads on the AGB and RGB as a function of GC age. Predictions of Charbonnel & Chantereau (2016) for the original FRMS scenario are shown for different values of metallicity (colors) and for two values of the η parameter adopted for Reimers mass loss along the RGB (0.5 and 0.65, solid and dotted lines respectively). The values derived in the present analysis are shown for the nine GCs (blue, red, and black stars, with the colors of the symbols indicating the theoretical track that has the closest [Fe/H] from that of each individual GC).