Each fouling experiment was repeated three times, and thus the accuracy of the results can be estimated: the standard deviation of the recorded lag-time was 10% (repeated experiments with stainless steel electrodes), 18% (for TiN coated electrodes) and 7% (graphite electrodes). The duration of each experiment was about 3 h, and all 27 experiments with stainless steel electrodes, 27 experiments with TiN coated electrodes and 10 experiments with graphite electrodes were carried out with new pairs of electrodes. Reduced number of experiments with graphite electrodes was motivated by the fact, that no fouling effects were observed with graphite.