Metal and precious metals laboratory: ongoing projects

Colorando Auro. Orfèvreries du Moyen Âge et recettes anciennes de la coloration de l’or: une approche analytique (Colorando Auro. Medieval silver and old recipes for the colouring of gold: an analytical approach) – Promoter: Helena Wouters (IRPA/KIK – Laboratories) – Copromoter: Gilberte Dewanckel (IRPA/KIK – Conservation) – Assistant: Amandine Crabbé
Project in the framework of the research campaign Stimulation of the Research in the Federal Scientific Institutes – January 2009-December 2012

The restoration of works of art contributes to their durability, but IRPA/KIK also seizes this opportunity to perform a profound study of the techniques employed in their manufacturing. Thus the long history of the restoration of the Reliquary shrine of Our Lady of Huy (13th century) has inspired a reflection on the medieval practice of the colouring of gold. This reflection led to the current project.

Shrine of Our Lady of Huy

The techniques for the colouring of gold, in Latin colorando auro, applied on silver and described in medieval manuscripts have for a long time been disregarded. As a result some of the restoration and cleaning treatments that have been carried out have been inadequate or have even caused some works to suffer irreversible damage. This study aims to broaden our knowledge of these colouring techniques. It will facilitate significant advances in the fields of the exact sciences, art history and the application of gilded silver and it’s restoration. The aims will be to gain insight in the chemical processes of recipes for the colouring of gold, to identify the results of these recipes and to determine the degradations due to time and the results of different methods for restoring or cleaning the colouration. Thanks to this new information it will be possible, among other things, to identify the silver that has been coloured following one of the recipes, to determine which one was used and to revise the techniques for it’s conservation-restoration.