Cambridge 7th to 9th September
Presenting Author:
Serena Panighello
<serena.panighello@unive.it>
article posted 22 Apr 2015
Serena Panighello
Serena Panighello is a PhD student in Chemical Sciences at the Department of Molecular
Sciences and Nanosystems, University Ca' Foscari of Venice and at the National Institute
of Chemistry of Ljubljana, Slovenia, with a research on the development and
application of spectroscopic
techniques for physico-chemical study of glass and its degradation.
She received the MSc diploma at the same university in Chemical Sciences for Conservation
and Restoration, with a dissertation on "Physical-chemical characterization of Pre-Roman and
Roman glasses by Laser Ablation ICP-MS and UV-Vis Reflectance Spectroscopy".
Investigation of glass leaching processes by laser ablation ICP-MS.
A selection of case studies
Panighello S. 1,2,*, van Elteren J.T.2, Orsega E.F.1, Moretto M.L.1 Kavcic A.2, Vogel-Mikus K.3,6, Tennent N.H.4, Wallert A.5
The analysis of archaeological and historical glasses remains a challenge for samples with physical and/or chemical damage on the surface of the artifact as a result of chemical instability of ancient glasses and often aggressive environmental conditions in which they remained, often for centuries or even millennia.
For archaeological (buried) glasses the moisture content in the ground results in leaching of alkali elements from the glasses, leading to glass weathering or corrosion as evidenced by discoloration or iridescence. Historical and modern glasses are affected by other types of diseases known as atmospheric corrosion and crizzling as a result of exposure to high levels of humidity and/or atmospheric pollution. In general two mechanisms are involved: de-alkalization (commonly referred to leaching) and network dissolution [1]. However, these mechanisms are not associated with ancient or historical artefacts only but also with e.g. all kinds of industrial glasses. The chemical resistance and weathering behavior of allegedly inert industrial glasses such as soda-lime, borate and crystal (lead glass) is largely studied nowadays. The chemical durability of these glasses should be incontestable as they are often used in industries directly related to human health (food, beverage, medicine, etc.).
In this work a selection of different archaeological, historical and artificially aged glasses were analysed by laser ablation ICP-MS in order to obtain quantitative elemental depth profiles related to different degradation phenomena. Case studies will highlight the elemental leachability of both archaeological/historical and contemporary/industrial glasses. Another case study concerned the altered blue pigment smalt (cobalt glass particles) in 17th century paint cross-sections via elemental mapping.
Laser ablation ICP-MS is an emerging tool to analytically investigate the mechanisms of glass degradation even in heterogeneous systems as paintings and till now unlikely candidates such as industrial glasses (Figure 1 below).
Figure 1. Schematic illustration of the sequence of steps in the glass degradation investigation, from degraded glass samples to interpretation of the analytical data. These steps are presented as a fractal system that grows and evolves in time, becoming more and more complex, giving more and more insight.
Reference:
[1] Newton R. and Davison S. (1989). Conservation of Glass, Butterworths, 1st edn., London
Institutions:
1 University Ca' Foscari of Venice (Italy)
2 National Institute of Chemistry, Ljubljana (Slovenia)
3 University of Ljubljana (Slovenia)
4 University of Amsterdam (The Netherlands)
5 Rijksmuseum, Amsterdam (The Netherlands)
6 Jozef Stefan Institute (Slovenia)