Preparing the foundation for stable gilding: Baroque craftsmen's empirical understanding of gesso gilding grounds

This paper is the fourth in a series covering Portuguese gesso gilding grounds from the late 13th to the 18th century, but with a special focus on the Baroque period when gilded surfaces played an important religious, political and social role in Portugal. This fourth paper concentrates on unravelling the motives of the craftsmen who chose to produce grounds for gilded surfaces using very specific materials and techniques: gypsum, as the raw material, and a double-structured layered system. It seems plausible that the properties of this type of ground, the religious and social importance and the function of the gilded objects, cultural influences from southern European, and the particular Portuguese historical context all contributed to this choice. This paper aims to contribute to enrich understanding of gilding technology and to inform conservation decision-making for the preservation of these gilded objects.