Exploring Benzyl Alcohol Derivatives and Related Compounds in the Cleaning of Oil Paintings

ABSTRACT

This study examines five benzyl alcohol derivatives and three chemically similar compounds and compares them against benzyl alcohol in gelled emulsions for the removal of overpaint during cleaning of oil paintings. Comparative cleaning tests using xanthan gels, Pemulen® TR-2 gels, and neat solvent were made on overpaint on fragments of a seventeenth-century test painting. This approach demonstrated that molecular changes to a benzyl alcohol core resulted in enhanced control during the cleaning process. In some cases a benzyl alcohol derivative enabled selective removal of non-original material, when benzyl alcohol appeared to affect the original paint. Select derivatives were also tested in an area of overpaint on a sixteenth-century oil on panel painting by Jan van Scorel in the Rijksmuseum Collection through modifying the chemical activity of benzyl alcohol. Finally, two GC-MS-based methods were used to monitor benzyl alcohol retention and possible oxidation in paint layers post-treatment.

KEYWORDS:

• Benzyl alcohol
• chemical derivatives
• molecular changes
• solvent cleaning
• gel cleaning
• xanthan
• Pemulen®
• oil paintings
• varnish removal

Acknowledgements

C. Liu. wishes to thank the Migelien Gerritzen Fellowship in Conservation and Conservation Science from the Rijksmuseum for funding this research. Special thanks to Gwen Tauber, former Senior Paintings Conservator, Rijksmuseum for testing select benzyl alcohol derivative xanthan gels during the cleaning tests for the treatment of the Jan van Scorel painting. Thanks to Saskia Smulders-de-Jong of the Rijksdienst voor het Cultureel Erfgoed (RCE) for performing the GC analysis of the overpaint of the Jan van Scorel painting. Authors thank Petria Noble, Senior Paintings Conservator and Head of Paintings Conservation at the Rijksmuseum, for her critical comments and improvement of the text.

Disclosure statement

The authors declare no potential conflicts of interest. C. Liu had examined and begun treatment on SK-A-3853 from 2019–2020 during an internship year. However, upon starting this research project, all cleaning tests performed on the van Scorel painting were chosen at the discretion of and performed by G. Tauber based on information relayed by C. Liu on results from tests on the seventeenth-century test painting.

Notes

1 Pemulen^® TR-2’s greater cleaning effect appears subtle/may not be evident from photographs of swabs used for clearance in Figure 5, however the difference is clearer when viewing directly under the microscope.