Glass - Back to the Future!



Presenting Author:
Teresa Palomar
<t.palomar@csic.es>

article posted 08 Feb 2016


Teresa Palomar is Doctor in Chemistry from the Autonoma University of Madrid, she has focused her research to the corrosion and conservation of inorganic materials from cultural heritage, especially on glass and metal. Currently, she is making a post-doc in the Centro do Vidro e da Cerâmica para as Artes (Lisbon, Portugal).










Effect of marine aerosols on the alteration of silicate glasses

Teresa Palomar1*, Anne Chabas2, David M. Bastidas3, Daniel de la Fuente3, Aurelie Verney-Carron2


Stained glass windows are the historical glasses most affected by atmospheric degradation. Several works have assessed the influence of pollution on degradation mechanisms, but the studies on the effect caused by marine aerosols are very scarce, previous works have shown that the presence of neutral salts (NaCl, KCl, CaCl2, MgCl2, NaBr, Na2SO4) dissolved in pure water lead to increase the corrosion rate of quartz and commercial glasses.

In this work is presented the study of the effect of saline aerosols on soda-lime, potash-lime and lead silicate glass samples. NaCl aerosols were deposited over a first set of samples of silicate glasses in the CIME, Chambre d'Interactions Matériaux-Environnement (LISA-UPEC, France), and afterwards they were exposed during 38 days to different relative humidity (RH) conditions: 20% RH, 100% RH and variable 20-100% RH, at a constant temperature (20ºC). The second set of samples was exposed to the real marine atmosphere of Cabo Vilano (Galicia, Spain) during three months. For comparative purposes, a 20th century stained glass window from the Treasury Department Delegation of Málaga, in the south coast of Spain, was also characterized. A set of analytical techniques to assess the physicochemical effects were used, including optical microscopy, scanning electron microscopy/energy dispersive X-ray spectroscopy, micro-Raman spectroscopy and small-angle X-ray diffraction.

Any alteration pathologies were observed on soda lime and lead silicate glasses exposed to simulated conditions, whereas the potash lime silicate glass presented fissures and new crystalline phases over the glasses including carbonates and sulphates. All the samples exposed in Cabo Vilano showed new crystalline deposits over their surface, potash lime silicate presented also small fissures, indicating that this glass was the least durable one. Similar deposits were observed in the 20th century stained glass window.

Institutions:

1 Depto. de Conservação e Restauro and Research Unit VICARTE-Vidro e Cerâmica para as Artes, Campus de Caparica, FCT-UNL, Quinta da Torre, 2829-516 Caparica, Portugal

2 Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), Universités Paris-Est Créteil et Paris Diderot CNRS, 61 Avenue du Genéral de Gaulle, 94010, Créteil, Cedex, France

3 Centro Nacional de Investigaciones Metalúrgicas (CENIM), Consejo Superior de Investigaciones Científicas (CSIC), Ave. Gregorio del Amo 8, 28040 Madrid, Spain.