This document specifies a test method for the determination of the covering of the edge of enamelled steel plate to be used in heat exchangers. It is applicable to all enamelling processes. The specified test method is applicable to plates with a thickness between 0,5 mm and 1,5 mm. It is not applicable where the current flow generated in the test exceeds 3 A. During the procedure, the edge of an enamelled steel plate to be tested is submerged in an electrolyte. An alternating current source and a stabilized voltage are connected to the plate. The recorded current is a measure of the covering at the edge. The International Standard ISO 28723:2008 has been prepared by Technical Committee ISO/TC 107 "Metallic and other inorganic coatings" and has been taken over without any modifications as EN ISO 28723:2011 by the Technical Committee of the International Organization for Standardization, CEN/TC 262 "Metallic and other inorganic coatings", the secretariat of which is held by BSI (United Kingdom). The responsible German committee is Working Committee NA 062-01-63 AA "Prüfung von Emails und Emaillierungen" ("Testing of vitreous and porcelain enamels") at NMP.