Preparing the foundation for stable gilding: the origins of materials and practices – a review

This paper is the fifth of a series and focuses on tracing the history of the use of gypsum based products as well as of the use of ground layers, centred on a review of published analytical evidence. The purpose is to contribute for the understanding of these long traditions which led to the choice of specific materials and practices used for producing gilding grounds in southern Europe. In fact, several practices and the raw material gypsum used in gilded surfaces do have an extremely long tradition, which can be traced back to the Pre-Pottery Neolithic B. The systematic use of these materials, especially the use of ground layers for decoration and other purposes, suggests not only an intention but also, somehow, the notion of a complex concept, the concept of a composite material, even at these very early periods, from which gilding origins. In addition, the particular case of Portugal shows that aspects such as religious, political, and sociocultural influences played a central role in the choice of gypsum as the raw material, which was curiously used exclusively for gilding.