Application of surface analysis techniques to the study of metal carboxylates in Southern Netherlandish oil paintings, Towards a better understanding through ToF-SIMS and XPS

Details

Supervisors

Delcorte, Arnaud ; Mederos-Henry, Francisco

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil physicien, à finalité spécialisée

Abstract

Historical paintings form an important aspect of our cultural heritage and their preservation is vital for honouring our history. Metal carboxylates, particularly copper and calcium oxalates, pose significant threats to historical oil paintings, and comprehending them is vital for proper artwork restoration. This work comprises two main sections. The main study utilized ToF-SIMS to detect and locate copper oxalate and calcium oxalate in cross-sections from Southern-Netherlandish oil paintings. The aim was to establish a reliable method for identifying these compounds, given their frequent occurrence in damaged paintings. Assessing the reliability and effectiveness of ToF-SIMS in achieving these objectives can provide insights into its potential for future similar research. We also characterized XPS spectra of metal oxalate powders. The XPS analysis of calcium, copper, lead, and zinc oxalates in historical samples has remained so far unexplored, making this theoretical investigation crucial for potential future research and foundational for historical sample examinations. Our results showed that we could detect CuC2O4- and CaC2O4- in ToF-SIMS. To confirm the presence of CuOx and CaOx in the samples, we verified consistency with ATR-µFTIR results, ion localization, and peak definition. Unfortunately, the mass resolution of ToF-SIMS does not allow us to conclusively confirm whether these peaks correspond to these ions. Exploring alternative techniques with enhanced mass resolutions, such as delayed extraction (which showed successful enhancement in this study), could be beneficial. The XPS study showed that it is possible to identify distinct characteristics of CaOx, CuOx, PbOx, and ZnOx, suggesting their potential identification in complex samples. Considering their limited detectability by ToF-SIMS, employing XPS for 3D analysis, particularly with a GCIB-equipped instrument, could be an intriguing avenue. However, before applying this to historical cross-sections, a systematic mock-up procedure is essential due to potential chemical changes and concerns about representation accuracy.