This document describes methods of scribing coated steel or test-pieces for corrosion tests, where the coating system is applied at dry film thicknesses of less than 500 µm. It is intended as a guideline only, being based on the results of a collaborative trial with no subsequent corrosion testing having been carried out to determine the suitability of the introduced scribe marks for such tests. This document covers the scribing of metallic panels or test pieces (chemically treated or not) made from: — steel; — galvanized steel; — aluminium alloys; — magnesium alloys. It does not cover the scribing of electroplated metal or clad aluminium panels.