Macroetching is a procedure for revealing the large-scale structure of a metallic specimen, that is, the structure visible with the unaided eye, by etching an appropriately prepared surface. This article provides information on the basic procedures for macroetching as well as the apparatus used. It discusses selected etchants for efficient macroetching of various metals and their alloys, including iron, steel, high-alloy steels, stainless steels, high-temperature alloys, titanium, titanium alloys, aluminum, aluminum alloys, copper, and copper alloys. The article also describes various conditions that are revealed by the macroetching of aluminum.

Magnesium and its alloys are among the most difficult metals to prepare for metallographic examination. This article describes specimen preparation processes, including sectioning, mounting, grinding, and polishing. It discusses macro and microexamination techniques as well as related etching processes, including macroetching and color etching based on polarized light enhancement. The article concludes with an overview of the effects of alloying elements, including aluminum, beryllium, calcium, copper, iron, lithium, manganese, rare earth metals, silicon, silver, strontium, thorium, tin, zinc, and zirconium.

Metallographic contrasting methods include various electrochemical, optical, and physical etching techniques, which in turn are enhanced by the formation of a thin transparent film on the specimen surface. This article primarily discusses etching in conjunction with light microscopy and describes several methods for film formation, namely, heat tinting, color etching, anodizing, potentiostatic etching, vapor deposition, and film deposition by sputtering. It provides information on the general procedures and precautions for etchants and reagents used in metallographic microetching, macroetching, electropolishing, chemical polishing, and other similar operations.