Non-invasive study of plaster application marks in the 16th century Great Siege wall painting cycle, Valletta, Malta

Abstract

Plaster layers are integral components of wall painting systems and their surfaces often preserve an extensive record of their properties and application. However, most research about wall painting plasters focuses on composition and performance. Only a limited number of published studies reports on the documentation and analysis of plaster surface marks (e.g. Centauro 1989; Zanardi 1996; Bandini & Lanfranchi, 2002), and most of these focus on marks related to preparations for painting (e.g. setting out, preparatory drawings), rather than those resulting from the plaster application process. A non-invasive examination of the 16th century Great Siege wall painting cycle in the Grand Master’s Palace, Valletta, Malta, using simple techniques and accessible tools, has revealed a wealth of plaster application marks preserved in the surface of the lime plasters (Gorodetska 2022). The study of these marks serves as an excellent example of how surface texture can provide unique insights into the properties of the plasters, the working methods of the plasterers, and current conservation problems of a wall painting.