Surface modification processes on European Union bronze reference materials for analytical studies of cultural artefacts

This paper presents research results obtained in the 4th Framework Programm e (1994-1998) of the Standards, Measurements, and Testing Programme of the European Union, DG XII: 'Improvement of means of measurements on archaeolog ical copper alloys for characterisation and conservation' (IMMACO) project. One of the aims of this project was to study copper alloy compositions of European objects dating from the Bronze Age to Roman times. This work has r evealed that five types of alloy seem to be particularly representative of what was produced in Europe during this period. These alloy compositions wi ll be certified as reference materials by the European Union. In the second part, artificial patinas have been made on the different bronze alloys usi ng electrochemical polarisation as the surface modification technique. The characterisation of the corrosion surfaces and interfaces formed during the treatment with light microscopy and scanning electron microscopy (SEM-EDX, X-ray mapping) have shown that the artificial patinas seem to be very clos e to those from excavations. As a consequence the patinated specimens can b e used as a substitute for genuine artefacts in the future to improve conse rvation techniques.