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A Study of Enamels: Conservation and History
of the Global Transfer of Technology
 

Overview

Enamelled objects- comprising a vitreous, glass-based material applied to a non-porous substrate such as porcelain, metal or glass- are important components of museum collections around the world. Far from being purely decorative items, they provide direct evidence of technological development through time, and are representative of the global political, socio-cultural and economic networks in which they were manufactured and traded.  

Within museum collections, enamels can be challenging to manage. Some recipes and colourants used in manufacture were less stable than others, leading to variations in the stability of individual enamel objects. Production techniques employed in the decoration and firing of enamels also impact the structure and appearance of the final product and may similarly affect the stability of enamels over time. Damage from humidity, pollutants or material degradation is irreversible. Methods of identifying deterioration early are therefore extremely important, allowing objects which are “at risk” to be identified.  

The aims of this project are: 

 

1. to better understand and identify the factors and physical processes influencing the deterioration of enamels in museum collections;  

2. to provide information on the compositional and technological nature of the enamels studied and thereby the museum collections; and  

3. to inform our knowledge of the global transfers of enamelling technologies between enamel manufacturing centres in the Early Modern Period.  

Addressing the Challenge

Research showing the correlation between enamel surface deterioration and hydration has recently prompted the use of non-destructive Optical Coherence Tomography (OCT) and Hyperspectral Imaging techniques to study enamels and their conservation. Previously applied to paintings and faience, a pilot study, by Dr Margaret Read with the ISAAC Research Centre, has demonstrated the applicability of these techniques to enamels. In particular, they are well-suited to the analysis of museum collections, as large numbers of objects may be studied non-destructively at relatively little cost and time. This work has also demonstrated that by using complementary techniques such as portable X-Ray Fluorescence (XRF), to provide information on the composition of the enamels, we can increase our understanding of the enamel production technology. However, these techniques have yet to be used together in a large-scale study of museum enamels of varying regions of production.  

This project will apply the recent pilot study findings to a larger scale analysis of enamel objects from the British Museum and V&A collections, in order to develop a non-destructive analysis methodology for the study of enamels. This will inform conservation priorities, allow a detailed understanding of the manufacture of enamels held in the collections, and, by comparison of objects across different regions and time periods, enable an investigation into the global transfer of enamelling technologies. Several analysis techniques will be used together to provide complementary information: 

 

 

  • Visual analysis, historical, and art historical research into the collections/objects studied;  

  • Optical Coherence Tomography (OCT) to analyse physio-chemical features of the enamel layers, including forms of deterioration and technological features;  

  • Hyperspectral imaging to determine hydration levels of the enamels, and thereby levels of enamel deterioration;  

  • X-ray fluorescence mapping and Raman spectroscopy for compositional analysis, as different “recipes”, colourant and production technologies may be associated with particular time periods or production regions, or even specific workshops. 

Making a Difference

Taking an interdisciplinary approach to the study of enamels in the British Museum and V&A Museum collections, this project aims to better understand the technological relations between historical enamels, and identify the state, or risk, of deterioration of enamels within the collections to aid conservation decisions. In doing so, the study aims to inform understandings of the nature of enamel technological exchanges taking place during the Early Modern Period on a global scale, and thereby contribute further understanding to the significance of the enamels in the Museums’ collections. The data gained from these analyses will also seek to demonstrate the applicability to the techniques used for other museums and collections, and explore points for refinement of the techniques themselves when applied  to enamels. 

Publications 

Read, M., Cheung, C.S., Liang, H., Meek, A. and Korenberg, C. 2021. A Non-Invasive Investigation of Egyptian Faience Using Long Wavelength Optical Coherence Tomography (OCT) at 2µm. Studies in Conservation 67, 168-175. https://doi.org/10.1080/00393630.2020.1871208 

 

Read, M., Cheung, C.S., Ling, D., Korenberg, C., Meek, A., Kogou, S. and Liang, H., 2019. A Non-Invasive Investigation of Limoges Enamels using both Optical Coherence Tomography (OCT) and Spectral Imaging: A Pilot Study. In: H. Liang and R. Groves, eds., Optics for Arts, Architecture, and Archaeology Vii. SPIE Optical Metrology, Munich, Germany, 24-27 June 2019. SPIE Proceedings 11058, 1105803 https://doi.org/10.1117/12.2527092

 

Liang, H., Sax, M., Saunders, D. and Tite, M., 2012. Optical Coherence Tomography for the Non-Invasive Investigation of the Microstructure of Ancient Egyptian Faience. Journal of Archaeological Science, 39, pp. 3683-3690. https://doi.org/10.1016/j.jas.2012.06.007

 

Liang, H., Peric, B., Hughes, M., Podoleanu, A., Spring, M. and Roehrs, S., 2008. Optical Coherence Tomography in Archaeological and Conservation Science - A New Emerging Field. Proceedings of SPIE, 7139, 713915. https://doi.org/10.1117/12.819499 

People

Supervisory Team: 

Professor Haida Liang, Nottingham Trent University 

Dr Sotiria Kogou, Nottingham Trent University 

Dr Capucine Korenberg, British Museum 

Dr Andrew Meek, British Museum 

Dr Lucia Burgio, Victoria and Albert Museum 

PhD Student:

Rebecca Mitchell (Nottingham Trent University)

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