Although using a metal reference electrode with the purpose of measuring the potential difference in direct contact with the electrolyte surrounding the structure does not seem logical, but the zinc reference electrode in clean seawater is suitable for many applications. The use of these electrodes in electrolytes other than sea water is not recommended.
It is essential that the zinc used in the production of zinc reference electrodes is sufficiently pure (zinc with a purity of at least 99.9% with a maximum iron content of 0.0014%). This reference electrode is cheaper and bulkier than the silver/silver chloride reference electrode and can be used instead unless a high degree of stability is required.
Measuring the potential using a zinc reference electrode in clean sea water shows a difference of about ±30 mV and using a silver/silver chloride reference electrode in sea water shows a difference of about ±5 mV.