Diagnosis of pathologies in ancient (seventeenth-eighteenth centuries) decorative blue-and-white ceramic tiles : Green stains in the glazes of a panel depicting Lisbon prior to the 1755 earthquake

Silva, TeresaFigueiredo, M. OndinaBarreiros, M. AlexandraPrudêncio, Maria Isabel2015-01-242015-01-242014-03Silva, Teresa P.; Figueiredo, Maria-Ondina; Barreiros, Maria-Alexandra; Prudêncio, Maria-Isabel - Diagnosis of pathologies in ancient (seventeenth-eighteenth centuries) decorative blue-and-white ceramic tiles : Green stains in the glazes of a panel depicting Lisbon prior to the 1755 earthquake. In: Studies in Conservation, vol. 59, nº 2, March 2014, p. 63-680039-3630http://hdl.handle.net/10400.9/2583Decorative panels of ceramic glazed tiles comprise a valuable cultural heritage in Mediterranean countries. Their preservation requires the development of a systematic scientific approach. Exposure to an open-air environment allows for a large span of deterioration effects. Successfully overcoming these effects demands a careful identification of involved degradation processes. Among these, the development of micro-organisms and concomitant glaze surface staining is a very common effect observed in panels manufactured centuries ago. This paper describes a study on the nature of green stains appearing at the surface of blue-and-white tile glazes from a large decorative panel with more than one thousand tiles, called Vista de Lisboa that depicts the city before the destruction caused by the 1755 earthquake. The characterization of green-stained blue-and-white tile glazes was performed using non-destructive X-ray techniques (diffraction and fluorescence spectrometry) by directly irradiating the surface of small tile fragments, complemented by a destructive scanning electron microscopy (SEM) observation of one fragment. Despite the green staining, analytical X-ray data showed that no deterioration had occurred irrespective of the blue or white color, while complementary SEM-EDX data provided chemical evidence of microorganism colonization at the stained glaze surface.engCerâmicaAzulejoPatrimónio culturalPreservação do patrimónioPatologiasDifracção de Raios XEspectrometria de raios XFluorescência de raios-XLisboa (Portugal)Diagnosis of pathologies in ancient (seventeenth-eighteenth centuries) decorative blue-and-white ceramic tiles : Green stains in the glazes of a panel depicting Lisbon prior to the 1755 earthquakejournal articlehttp://dx.doi.org/10.1179/2047058413Y.0000000094