Gold leaf Murano glass piastras‘ performance in the trencadís Catalan modernism mosaic: recognition of primary alteration patterns

Abstract

Gold leaf Murano glass is a unique product that over the centuries, especially during Byzantine period, has been used as facing forming big flat or curved mosaics that result in an architecture full of light and symbolism. This product is presented in a format of squared piastras with the same approximate dimensions that the gold leaves ones have (8x8 cm). Piastras are cut in smaller squares (1-1,5cm) in order to obtain the tiles that form mosaic’s cladding. This cladding technique was incorporated during Catalan Modernism. Through this technique, beautiful pieces of tesseras of gold leaf Murano glass combined with others of opaline glass. In order to overcome the artistic challenges from this architectural movement, new mosaics were placed outdoors in order to shine by the incident sun beams and the square tiles were replaced by irregular tiles that form polygonal meshes capable of coating double curvature surfaces with great elegance. This location and prolonged exposure to the weather cause, over time, a deteriorated appearance, despite being composed of great resistant materials such as gold and glass. Studies oriented to know the phenomenology of this deterioration are being carried out and its impact on the expected durability of this coating. Being a handmade product and completely manual execution, the first studies have aimed to identify the primary anomalies that are originally generated in the different layers of this product at the time of manufacture, transport and handling. Knowing these primary anomalies must allow to prevent their occurrence and reduce their incidence in the manifestation of so-called secondary anomalies. All this in order to prolong the useful life of this appreciated architectural cladding.