Artificial Aging Trials to Imitate Copper Corrosion on Paper with Four Copper-containing Pigments

This paper describes the examination of four copper-containing pigments that catalyze copper corrosion on paper and investigates methods to recreate the damage patterns through artificial aging. The series of tests focused on verdigris as the main catalyst for this damage type but also included atacamite, malachite and azurite in which the damage pattern occurs less frequently. The artificial aging methods include thermal aging, hydrothermal aging, light aging, and combinations thereof. Investigations into pigment changes, the migration behavior of the copper ions and the degree of paper degradation were carried out through Raman spectroscopy, scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX) and size-exclusion chromatography with multi-angle light scattering (SEC-MALS) and labeling of oxidized functionalities. Hydrothermal aging in a closed glass vessel as well as the combination of hydrothermal and light aging overall yielded results with the closest resemblance to historical examples of copper corrosion on paper.