Fig. Drawing by Hans Holbein the Elder (1514-1515), Inv.no. KKSgb2991, Statens Museum for Kunst
Ongoing research project in CATS
The research project is financed by a major grant from the Danish Ministry of Culture, and began in May 2015 and runs until April 2016. The project is a collaboration between CATS and the Royal Library, National Library of Denmark.
The project aims to examine and understand a degradation phenomena observed in graphic works (on paper, parchment and photography), where certain lead white pigments darkens dramatically and may become completely black. This reaction is believed to primarily be an air pollution phenomenon, but other causes are also investigated.
The pigment lead white (basic lead carbonate) has been used for centuries and the fact that lead white can darken or turn black over time (by conversion to the black mineral galena) is a known fact. However, the phenomena is described primarily for oil paintings and murals. This research project investigates the degradation of lead white in both mock-ups and real artworks. Tests are carried out by exposing test samples painted with the pigment to air containing sulfur compounds. Followed by analyses of the changes in the color and the degradation products.
Selected original works from SMK and the Royal Library are investigated and the results from the research project will contribute to future possible precautions regarding the museums exhibition and storage conditions.