Degradation-induced fluorescence patterns of zinc white in watercolours (ADSS/DRFART7P/61826)

The aim of this research is to establish the relation of degradation processes with specific fluorescence patterns of zinc white pigments in order to propose a methodology for an informed visual interpretation of historic works of art leading to implementation of suitable art conservation treatments and reliable authentication.

Introduced in 1834 by Winsor and Newton, zinc white became widespread as a watercolour pigment following concerns over the safety of lead white.[1] Aged watercolours containing zinc oxide now pose significant problems for art professionals as degradation has led to discolouration of surrounding paper and media.[2] This degradation is often linked to the pigment’s production method which can yield distinct fluorescent patterns.[3]

UV fluorescence of zinc white pigments is characterised by various light intensities as well as a range of colours from dark khaki to bright yellow-green. While the stronger intensities are linked with an abundance of interstitial cations within the crystal lattice,[4] colour variation arise from the combination of blue and green fluorescing nanocrystals which are fundamental compounds of the zinc white particle structure.[5] Sources indicate that these fluoresce characteristics may change upon ageing as a result of photo-degradation and hydrolysis reactions which, in turn, has a significant effect on the zinc oxide and other pigments in the vicinity.[6] There is ambiguity about which of the component nanocrystals in zinc white particles are primarily responsible for these degradation reactions and therefore new research is required to uncover the precise mechanism of degradation and its impact on fluorescence.
This studentship aims to uncover the degradation mechanism of zinc white in watercolours and its relation to specific fluorescence patterns using a range of sampling and accelerating aging methods, crystallographic and spectroscopic analysis as well as imaging and microscopy. Careful isolation of the pigment’s fluorescence will lead to the creation of a diagnostic tool for art professionals in an attempt to inform conservation treatments and prevent further degradation occurring on historic and contemporary works of art.

[1] Kuhn, H., 1986. Zinc White. In: R. L. Feller, ed. Artists Pigments: A Handbook of their History and Characteristics. Cambridge: Cambridge University Press, pp. 169-186.
[2] Colbourne, J., 2006. Pigment, Extender, or Adulterant: a Discussion on Artists’ White Pigmetns in Aqueous Medium in the Early Twentieth Century. Edinburgh, ICON
[3] Hey, M., 1987. Chinese White - A Potential Source of Trouble on Paper?. In: A. Vendl, B. Pichler, J. Weber & G. Baink, eds. Wiener Berichte ueber Naturwissenschaft in der Kunst . Vienna: ORAC, pp. 362-369.
[4] Klingshirn, C., 2007. ZnO: Material, Physics, and Application. ChemPhysChem, 8(1), pp. 782-803
[5] Morley-Smith, C. T., 1958. Zinc Oxide - A Reactive Pigment. Journal of Oil and Colour Chemists Association, 74(2), pp. 85-97
[6]Markham, M. C. & Laidler, K. J., 1953. Kinetic Study of Photo-oxidations on the Surface of Zinc Oxide in Aqueous Suspensions. Journal of Physical Chemistry, 57(3), pp. 363-389

Enquiries regarding this studentship should be made to: Dr. Charis Theodorakopoulos, +44(0)191 227 4611, [Email Address Removed]

For further details of how to apply, entry requirements and the application form, see
https://www.northumbria.ac.uk/research/postgraduate-research-degrees/how-to-apply/
Please ensure you quote the advert reference above on your application form.