Gilding and silvering surface decoration techniques, and copper provenance studies of the tomb of D. Afonso of Portugal (15th century)

The tomb of D. Afonso of Portugal (1390-1400), king D. Joao I first born raises questions about the production of its different elements, which according to their typology were not all made simultaneously. The singularity of both the composition of the metal and the type of techniques - fire gilding and amalgam silvering - used in the decoration of some elements causes difficulties in the attribution of the tomb to a Flanders or to a Portuguese workshop. The aim of this work is to attribute to the tomb a possible production origin based on the study of the copper provenance. Special attention was given to decorative techniques because these could bring further information about the production of the elements. For these purposes PIXE and SEM-EDS analysis were used. PIXE analysis revealed the importance given to the choice of an almost pure copper for the tomb pieces, since it has a direct consequence in the manufacture and decorative techniques. It also allowed concluding that the composition of the pieces correlates very well with the coins minted during D. Afonso V period, further studies being necessary to compare the results with objects from Flanders. Analysis by SEM/EDS characterized the gilded coating as being made of a layer of Au+Hg applied by fire amalgam. In the silvered coating, the existence of two separate layers characterises the silvering technique as having been executed by the application of an Ag+Hg amalgam, on top of a first layer of Au+Hg, also applied by amalgam. Copyright (C) 2008 John Wiley & Sons, Ltd.