Low apparent valence of Mg during corrosion

•Data reanalysis confirmed prior conclusions.•EIS data did not provide good measurements of the corrosion rate.•Electrochemical evaluated corrosion rates were less than those evaluated by weight loss.•The value of the apparent valence was in many cases less than 1.0.•Part of the corrosion may be isolated by hydrogen gas from electrochemical measurement.

Our recent data on Mg corrosion has been reanalysed because of the recent criticism that our previous data analysis was inadequate. Re-analysis leads to similar conclusions as previously. The apparent valence of Mg during corrosion was in each case less than 2.0, and in many cases less than 1.0. Moreover, these values were probably over-estimates. The low values were consistent with the evolving hydrogen gas acting as an insulator, so that the corrosion of parts of the specimen could occur isolated from the electrochemical measurement system.