Response to comments on E. Huttunen-Saarivirta et al., "Kinetic properties of the passive film on copper in the presence of sulfate-reducing bacteria"

The Comments by Martino et al.¹ on the original manuscript² criticize our interpretation of the existence and properties of the Cu₂S barrier layer of the passive film that forms on the surface of copper in SRB-bearing groundwater at 10°C. First, it is necessary to recognize that this discussion involves two forms of copper, which we refer to as “pure copper (P-Cu)” (nominally > 99.999%) and “oxygen-free phosphorous copper (OFP-Cu)”. P-Cu has been used in the majority of our work^3–6 with only some of our later work employing OFP-Cu,² a point that does not seem to be appreciated by Martino et al.¹ On the other hand, the Shoesmith group appears to have concentrated exclusively upon OFP-Cu, at least in recent years.^7–11 This difference is of crucial importance in responding to the critique by Martino et al.¹