Our numerical investigation was motivated by FFC results showing lower values of the NMR relaxation time T 1 in the case of Na 2 SO 4 as compared to NaCl salt crusts (Fig. ). However, the value of T 1 obtained using MD simulations for salt concentrations close to the experimental values (c s = 4 kg/mol for NaCl, c s = 1 kg/mol for Na 2 SO 4 ) show a slightly lower value for T 1 in the case of NaCl as compared to Na 2 SO 4 , namely T 1 ≈ 0.6 s vs. T 1 ≈ 0.9 s (Fig. ). This apparent contradiction between experiments and simulations could indicate that the differences observed experimentally for T 1 in Fig. are not primarily induced by differences in surface properties between the two salt crusts, but rather by differences in their respective pore size distributions. This would suggest, that there is a larger proportion of small pores in the Na 2 SO 4 crust as compared to NaCl, which is consistent with the pore size distributions extracted from SEM images (Fig. ) and the pore size dependence of the relaxation rate shown in Fig. . However, in our SEM analysis, we lack data for pore sizes smaller than 1 micrometer and thus no definite conclusion can be made from this study, leaving room for future pore size characterization covering the full pore size range.