Despite the qualitative agreement between the different datasets and the model, we observe that the local charging appears to require longer times than the model predictions from Equation . It is worth mentioning that the experiments were executed using the same stock solution in the chronology of decreasing slope (circles, diamonds, squares), which could indicate some effect of aging of the electrolyte. From the model perspective, such deviation can be either due to an increased α due to an underestimated required potential, or non-ideal charging. The latter can potentially be due to parasitic capacitance of the STM tip, as the different datasets were performed with different STM tips. It should be stressed that the model considers 1D charging and an instantaneously applied potential between the 2 electrodes. Parasitic charging along the STM tip might therefore perturb the pulse arriving at the apex, which we cannot measure in our experimental setup. In fact, it has been demonstrated recently that the machining resolution of a pulsed etching process can be improved for a given pulse length by introducing an additional capacitor that slows down the charging , further suggesting that pulse deformation at the tip may be responsible for the discrepancy between the model and experiments.