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

This article presents research results obtained in the 4th framework (1994- 1998) of the Standards, Measurements and Testing Program (SM&T) of the Euro pean Union, DG XII : the IMMACO project (Improvement of Means of Measuremen ts on Archaeological Copper-alloys for characterization and conservation). One of the aims of this project was to study copper alloy compositions of E uropean objects dating from the Bronze Age to Roman Times. This work has re vealed that five types of alloy seem to be particularly representative of w hat was produced in Europe during this period. These alloy compositions wil l be certified as reference materials by the European Union. In the second part, artificial patinas have been made on the different bronze alloys usin g electrochemical polarizations as the surface modification techniques. The characterization of the corrosion surfaces and interfaces formed during th e treatment with light microscopy (LM) and scanning electron microscopy (SE M/EDX, X-Ray mapping) have shown that the artificial patinas seem to be ver y close to those from excavations. As a consequence, the patined specimens can be used as a substitute for guenine artifacts in the future to improve conservation techniques.