This is not a mechanical test. however, the chemical composition of engineering alloys, e.g. steels and aluminium alloys, can determine their mechanical properties and their response to heat treatment.

A quick and accurate determination of the chemical composition of metals can be made by optical emission spectrometer (OES). An electric arc is struck between the solid metal sample and a tungsten electrode. The light from the arc can be separated into its various wavelengths and the intensities measured. The chemical composition can thus be determined in a matter of seconds and to an accuracy of, typically, 0.01 weight percent.

Grey cast iron can pose a problem to analysis by OES, the free graphite in the matrix can deceive the spectrometer and produce gross inaccuracies. By remelting the cast iron surface with a plasma arc or similar heat source, the resultant liquid will cool quickly as white cast iron, which may be analysed successfully.