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Journal of Materials
Volume 2013, Article ID 972018, 6 pages
http://dx.doi.org/10.1155/2013/972018
Research Article

Decorative 18th Century Blue-and-White Portuguese Tile Panels: A Type-Case of Environmental Degradation

1Unit of Mineral Resources and Geophysics, LNEG, Estrada da Portela, Apartado 7586, 2610-999 Amadora, Portugal
2CENIMAT/I3N and Materials Science Department, Faculty of Sciences and Technology, New University of Lisbon, 2829-516 Caparica, Portugal
3Unit of Product Engineering, LNEG, Estrada do Paço do Lumiar, 22, 1649-038 Lisbon, Portugal
4Instituto Tecnológico e Nuclear, Instituto Superior Técnico (ITN/IST), Universidade Técnica de Lisboa, EN 10, 2686-953 Sacavém, Portugal
5GeoBioTec Research Center, University of Aveiro, 3810-193 Aveiro, Portugal

Received 19 November 2012; Revised 8 January 2013; Accepted 9 January 2013

Academic Editor: Eugen Culea

Copyright © 2013 Teresa P. Silva et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Decorated glazed ceramic tiles are used as an ornamental art, constituting an important cultural heritage whose preservation is mandatory. Environmental conditions are responsible for the degradation of exposed ancient tile panels originating various pathologies, related to the development of microorganisms. This is the case of a valuable 18th century blue-and-white Portuguese tile panel called “Cura do Cego,” belonging to the collection of the National Tile Museum (MNAz), where green stains are nowadays observable in the glaze. A prospective diagnosis of this green tarnishing was the aim of the present work. Small tile fragments were directly irradiated using nondestructive techniques: X-ray fluorescence spectrometry with a wavelength-dispersive system (WDXRF) for chemical characterization of the tile glaze and X-ray powder diffraction (XRD) to assess the phase constitution of both the glaze and the ceramic body. A destructive technique (scanning electron microscopy with energy-dispersive system (SEM/EDS)) was applied to tentatively infer the chemical changes induced in the glaze by the green staining and also to characterize the morphology of the microorganisms associated to this staining. The obtained results are reported and discussed, as a preliminary step for testing an innovative nondestructive decontamination technique applying gamma radiation, particularly suitable for overcoming such tile pathologies.