The past, present and future of lead white in Denmark’s national graphic art collections

A methodical examination of the graphic collections at the National Gallery of Denmark (SMK – Statens Museum for Kunst) and Danish Royal Library (RL) has shown that circa 900 objects
from the SMK are affected by the darkening of white highlights, while up to 200 cases have been estimated to exist at the RL. Lead white was identified on all the objects studied. Artworks and housing materials from both institutions, together with a group of test samples created in the laboratory, have been examined by analytical means to better understand and locate the degradation sources. The levels of H2S in storage and galleries were also measured.In the housing materials from the SMK and RL, sulfur products were identified. Results point out that the degradation can be attributed to a combination of poor archival housing materials, outside pollutants and, in some locations, the presence of many people as well as humidity.