A standard electrode offered by the assignee of the present invention includes a noble metal electrode disc soldered to a stainless steel substrate. The substrate includes a smaller diameter disc projection and a larger diameter body section. The substrate body section has a threaded blind end bore adapted threadedly to receive part of the electrode arbor or spindle. The substrate and electrode disc are inserted in a TFE fluorocabon sleeve. This sleeve is shrunk fit into an interference fit with the stainless steel substrate to form a seal therebetween. This plastic covered electrode has been successful, but the electrode disc is permanently connected to the stainless steel substrate which in turn is sealed to the TFE fluorocarbon sleeve. Therefore, the entire electrode must be removed and replaced by a different electrode if a different electrode disc is required for comparative testing functions or for different applications.