CATS presented the poster Lead white blackening on graphic art at the Indoor Air Quality (AIQ) 2016 International Conference in Birmingham, UK

The blackening of lead white pigments is a well-known degradation phenomenon, which previously has been reported for paintings, murals, illuminated manuscripts, prints and drawings.
However, since the discovery of many master drawings in the Statens Museum for Kunst (Denmark) collection, which has blackened within the last 10-20 years, we are in the process of investigating the extent and source of this problem. Our survey also included parts of the print and photograph collection of The Royal Library.

We found the occurrences of darkened lead white on artist drawings, lithographs, and, surprisingly, even on historic photographs, where the white pigment has been used as a retouch in the highlight areas. At StatensMuseum for Kunstabout half of all the master drawings, which contain lead white pigment, may be affected. At the Royal Library about 200 cases have been identified.