ISO 4969:2015 establishes guidelines for the macroscopic examination of steel by hot etching, room temperature etching and electrolytic etching. The method has very wide application. Selection of the type, concentration and temperature of the reagent, the etching apparatus and the conditions of surface preparation of the test piece make it possible to achieve the required aim. NOTE It might be difficult to see fine voids and cracks and discriminate between them and determine their nature by macroetching.