The use of in situ non-invasive techniques as powerful tools in the investigation of eighteenth century Chinese wallpapers from the National Museum of Ancient Art—Lisbon

The National Museum of Ancient Art in Lisbon (MNAA) hosts the most important Portuguese public collection of art. Among its different types of artworks, a set of six Chinese wallpaper panels from the eighteenth century is present; they represent the production of porcelain and have been donated to the Museum in 1949. Despite the large interest that has raised around these kinds of artefacts, few technical studies have been carried out to date on Chinese wallpapers. In this study, a non-invasive investigation of the wallpaper panels from the MNAA by means of portable devices is described. More specifically, the combined use of technical photography (namely UVF, Vis and IR photography), Vis-NIR-FORS and EDXRF allowed to carry out a preliminary diagnostic survey, which higlighted an improper handling of the wallpapers prior to their donation to the Museum, and poor conservation conditions of the paper sheets. Furthermore, it allowed for the identification of the painting technique, the main pigments, and their distribution; the presence of inorganic pigments (such as vermilion and lead white) and organic dyes (e.g. anthraquinone-based red dyes and indigo), used both as overlapping layers and mixtures, has been determined.