Application of sol-gel based sensors to environmental monitoring of Mauméjean stained glass windows housed in two different buildings at downtown Madrid

Abstract

Degradation of historical stained glass windows is mainly caused by acid attack enhanced by humidity and pollutants. Accordingly, their preventive conservation should include environmental evaluation. Mauméjean’s stained glass windows (c 1940) of two buildings located at downtown Madrid have been monitored by sol-gel sensors of acidity and temperature. The philosophy was the application of innovative glassy sol-gel sensors to assess the conservation conditions of stained glass windows, i.e. modern materials for preservation of historical materials. Conservation conditions (environmental acidity and temperature) of restored and non-restored stained glass windows have been recorded throughout 13 months. The main contributing parameter to outdoor acidity is proximity to road traffic, which produces acid species able to diminish two units of pH with respect to neutral conditions. This acid environment affects both sides of stained glass windows, even in those protected with a glazing system, which allows natural ventilation. Other contributing parameters to increase the air acidity were façade orientation, sensor position, distance to pollutants sources, human interaction and uncontrolled ventilation.La degradación de vidrieras históricas se debe fundamentalmente al ataque ácido favorecido por la humedad y los contaminantes. Por tanto, su conservación preventiva debe incluir una evaluación ambiental. Se han evaluado vidrieras de Mauméjean (c 1940) de dos edificios del centro de Madrid mediante sensores sol-gel de acidez y de temperatura. La filosofía consistió en aplicar dichos sensores basados en materiales vítreos para tasar las condiciones de conservación de vidrieras del patrimonio, es decir materiales modernos para la preservación de materiales históricos. Las condiciones de conservación (acidez ambiental y temperatura) de vidrieras restauradas y no restauradas se han registrado durante 13 meses. El principal parámetro que contribuye a la acidez ambiental es la proximidad del tráfico rodado, que origina especies ácidas capaces de disminuir el pH dos unidades respecto a la neutralidad. Este ambiente ácido afecta ambas caras de las vidrieras, incluso si están protegidas por acristalamientos que permiten la ventilación natural. Otros parámetros que contribuyen son la orientación de la fachada, la posición del sensor, la distancia a los focos de contaminación, la interacción humana y la ventilación no controlada.

Keywords

• sol-gel sensors
• stained glass windows
• acidity
• temperature
• pollution
• sensores sol-gel
• vidrieras
• acidez
• temperatura
• contaminación