A process in which corrosive solutions are used to selectively remove or stain selected micro structural components from a polished metal surface so that the micro-structure can be seen using a reflected light (metallurgical) microscope or the overall structure of metal can be seen by the naked eye (macro-etch). There are many hundred different etch solutions, each one will reveal one or more specific micro-structural components. The etch characteristics of some etches will be altered by traces of unusual elements, with the result that it may take some time and effort to find the optimum etch conditions for some archaeological alloys as they do not fall into the ‘standard’ com-positional ranges for the etches.