Documentation of Artistic Production Patterns and Alteration Pathologies in Glass and Glazes through Micro Computed Tomography (µ - CT)

Abstract

Glass and ceramic objects are intrinsically connected to their decorations, which can be very different according to their chronology and function. The most common decoration in glass was to use two different coloured glasses, such as in core-formed vases or filigree and millefiori glass canes. Surface paintings such as enamels, grisailles, sanguine, and cold paintings are very common in stained-glass windows, reverse paintings, and magic lanterns’ slides. And, finally, glass can also be decorated with induced crystallization and post-productional treatments such as white and opaque red glass, yellow silver staining, or coloured glazes, used in stained-glass windows, glassware, and ceramics. In this work, developed through a FIXLAB action (H2020 project IPERION HS), we used micro-computed tomography (μ-CT) to analyse the surface and the internal structure of different pieces (stained glass, glass beads, porcelain, tiles, etc.) in a non-destructive way. The objective of this project was to know how the objects were produced and their alteration state through the characterization of surface decorative layers, the identification of the crystalline particles, and the evaluation of alteration pathologies. Results showed that decorations with a different chemical composition were observed clearly, even in very altered glasses, as well as the bubbles produced during manufacturing. The thickness of the decorative layer in pieces from stained-glass windows and glazed ceramic was also estimated. This technique was especially interesting to study the distribution of inclusions and porous in ceramic pastes and mortars. It is, therefore, a very useful and promising technique to characterize the decoration, the alteration pathologies and production patterns in different glasses, glazes and ceramics.