Abstract
Ultramarine blue paint layers in oil paintings can be affected by ultramarine ‘disease’ or ‘sickness’: a phenomenon described by a grey appearance and a loss of detail in the artwork. An explanation for this phenomenon is an interaction between the organic binder network and ultramarine pigment, with the pigment acting as a catalyst for the breakdown of the network. This breakdown results in micro-cracks in the paint film, which influences the appearance of the artwork. To investigate the possible catalytic property of ultramarine pigment, a test reaction – the dehydration of methanol to dimethyl ether – was carried out, with and without ultramarine pigment present in a micro-reactor with in-line gas chromatography mass spectrometry. It was observed that a higher yield of dimethyl ether was obtained in the presence of ultramarine pigment, confirming that ultramarine pigment possesses catalytic properties similar to commercial zeolitic silica-alumina catalysts.
Original language | English |
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Pages (from-to) | 25-32 |
Number of pages | 8 |
Journal | Journal of Cultural Heritage |
Volume | 45 |
Early online date | 12 May 2020 |
DOIs | |
Publication status | Published - Sept 2020 |
Funding
This work is financially supported by AkzoNobel . The authors would like to thank: Pieter Paul Pothoven (artist) for providing the lapis lazuli rock, Lloyd Smith of the University of Madison for offering the possibility to perform the GC–MS experiments, Ryan Wilkinson of Virent for the help in setting up the experimental catalysis experiments, Sergei Matveev of the University of Utrecht for the SEM/EDX and SEM/WDS analyses, Luc Megens and Annelies van Hoesel of the Cultural Heritage Agency of The Netherlands (RCE) for the XRD instrumentation and assistance.
Keywords
- Catalysis
- GC–MS
- Lapis lazuli
- Ultramarine pigment