HMTY-KM (Black Copper) and the egyptian bronzes collection of the Musee du Louvre

At the instigation of the Musée du Louvre’s Department of Egyptian Antiquities, an intensive programme to study black bronze has been carried out at the Centre de Recherche et de Restauration des Muse´es de France. Systematic research has been undertaken on the museum’s
collection to identify objects that might have an intentional black patina.
The same experimental protocol has been applied to all the objects, alllowing this study to be one of the most important coherent investigation on this type of bronze decoration. It involves the use of non-invasive analytical methods in order to obtain the maximum amount of information
possible about the chemical nature and structure of the surface layer. The protocol makes it possible to compare objects and to propose an interpretation of how this decorative technique evolved during the Egyptian period.
Based on previous stylistic investigations (by J. Cooney, 1966) and personal observation, sixteen objects dating from the Middle Kingdom to the Late Period were selected. Thanks to elemental analyses, twelve of them were identified as being intentionally patinated. Only ten of these could be described as hmty-km, because the base patinated alloy contains small amounts of gold and/or silver and the black patina is made up mainly of cuprous oxide Cu2O (cuprite). Among the four other objects, one patina is very close to the black bronze patina, but contains neither gold nor silver. Three other pieces have an unusual patina. A lack of other comparable examples makes it very difficult to determine whether the patinas are of ancient origin.