Cultural heritage objects, such as paintings and record documents, serve as unique materials with complex chemical systems that have been exposed to a range of environmental conditions. These objects require many forms of scientific analysis in order to better understand and guide preservation and conservation treatments. Generally, this requires the combined knowledge of curators, conservators, and scientists to protect these objects. Our group has been working in collaboration with the University of Delaware’s Art Conservation Department and the Winterthur Museum to tackle some of these interdisciplinary problems. Additionally, graduate students have been able to work on projects from institutions across the globe, from the Rijksmuseum (the Netherlands) to the Palace Museum (China).
To improve our understanding of the complex chemical interactions occurring in paint samples, our group deconstructs the complex systems into models to analyze them spectrochemically. Creating simplified systems allows for the study of multiple processes to assess the complex systems. Current phenomena of interest to the group is the interaction of copper-based and arsenic-based pigments with organic binders, as well as other possible environmental factors. In the case of copper-based pigments, like verdigris [Cu(OH)2(CH3COO)2●5H2O], the reactive nature of copper creates alteration products, with either fatty acids from the oil binder or resinous acids from the resin glazes. In the case of arsenic-based pigments, the degradation product of arsenolite [As4O6] has been found to migrate through multilayer paint films away from the original arsenic containing layer. In both systems, the questions revolve around the migration and further interactions of the chemical species.
- Wiggins, M.B.; Alcantara-Garcia, J.; Booksh, K.S. “Characterization of copper-based pigment preparation and alteration products.”MRS Advances 2017 (submitted)