Conservation of 19th and early 20th century oil paintings : studies of pigment discolouration by scanning electron microscopy

Field	Value	Language
dc.contributor.author	White, RE
dc.date.accessioned	2015-09-22T03:28:56Z
dc.date.available	2015-09-22T03:28:56Z
dc.date.issued	2007
dc.identifier.uri	http://hdl.handle.net/10453/37293
dc.description	University of Technology, Sydney. Faculty of Science.	en_US
dc.description.abstract	The discolouration of artistic oil paintings due to pigment interaction has been a concern for artists and painting conservators since the early 1800s. Since then there has been considerable speculation on the origin and mode of this discolouration. This project sought to determine what discolouring interactions between pigments exist in historic oil paintings and to understand the mechanisms involved. The discolouring pigment system was studied using x-ray diffraction, thermal analysis, x-ray microanalysis techniques and hydration experiments using an Environmental Scanning Electron Microscope. A discolouring chemical interaction between cadmium yellow (a cadmium sulfide pigment) and malachite (basic copper carbonate) was identified. The darkening reaction between copper containing pigments and the range of cadmium sulfide pigments was established to be the only discolouring that occurs between artistic pigments investigated in this work. This interaction occurs due to copper ions being mobile in the drying oils used for oil painting. The copper ions are taken up by the oil medium and transported throughout the oil layer to adjoining paint layers. Any cadmium sulfide present in the oil painting will undergo ion exchange at its surface with the copper ions in the medium to produce copper sulfide. The copper-cadmium ion exchange was found to continue until the cadmium sulfide is completely converted to copper sulfide. For the combination of cadmium yellow and malachite it was established that the discolouring copper sulfide was covellite, CuS.	en_US
dc.format	Thesis (PhD)	en_US
dc.language.iso	en	en_US
dc.relation	https://opus.lib.uts.edu.au/bitstream/10453/37293/8/02whole.pdf
dc.rights	info:eu-repo/semantics/openAccess
dc.rights	au.edu.uts.lib/ppc
dc.rights	The author owns the copyright in this thesis including all reproduction and reuse rights for the work. The work may not be altered without the permission of the copyright owner. Attribution is essential when quoting or paraphrasing from this thesis.
dc.subject	Oil paintings.	en
dc.subject	Conservation of paintings.	en
dc.subject	Discolouration.	en
dc.subject	Discolouring pigment interaction.	en
dc.subject	X-ray diffraction.	en
dc.subject	Thermal analysis.	en
dc.subject	X-ray microanalysis techniques.	en
dc.title	Conservation of 19th and early 20th century oil paintings : studies of pigment discolouration by scanning electron microscopy	en_US
dc.type	Thesis
utslib.copyright.status	open_access

Abstract:

The discolouration of artistic oil paintings due to pigment interaction has been a concern for artists and painting conservators since the early 1800s. Since then there has been considerable speculation on the origin and mode of this discolouration. This project sought to determine what discolouring interactions between pigments exist in historic oil paintings and to understand the mechanisms involved. The discolouring pigment system was studied using x-ray diffraction, thermal analysis, x-ray microanalysis techniques and hydration experiments using an Environmental Scanning Electron Microscope. A discolouring chemical interaction between cadmium yellow (a cadmium sulfide pigment) and malachite (basic copper carbonate) was identified. The darkening reaction between copper containing pigments and the range of cadmium sulfide pigments was established to be the only discolouring that occurs between artistic pigments investigated in this work. This interaction occurs due to copper ions being mobile in the drying oils used for oil painting. The copper ions are taken up by the oil medium and transported throughout the oil layer to adjoining paint layers. Any cadmium sulfide present in the oil painting will undergo ion exchange at its surface with the copper ions in the medium to produce copper sulfide. The copper-cadmium ion exchange was found to continue until the cadmium sulfide is completely converted to copper sulfide. For the combination of cadmium yellow and malachite it was established that the discolouring copper sulfide was covellite, CuS.

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http://hdl.handle.net/10453/37293