Problemi di conservazione delle pitture murali del Cortile di Michelozzo in Palazzo Vecchio

The cycle of the wall paintings in the Cortile di Michelozzo at Palazzo Vecchio in Firenze represents the views of some cities of Austria, Bohemia, Hungary and Tyrol, commissioned in the 1565 by Cosimo de' Medici for the wedding between his son Francesco and Giovanna d’Austria. The views have been object of various restorations and, in the half of the past century, the detachment of many views was performed. Currently, most of the views have serious problems of conservation and their fruition is compromised . Starting from the analysis of the past restoration works, this paper describes the most important results obtained through analysis in infrared spectroscopy (FT-IR) and gas chromatography-mass spectrometry (GC-MS) on the views of the city of Possonia (now Bratislava), which was not detached. The analytical procedures adopted allowed to assess the presence of gypsum spread over the whole pictorial surface and mainly the presence of egg as the proteinaceous binder employed in this pictorial work. The formation of gypsum is related with the air pollution as well as with the high amount of water affecting the walls. Key-Word: wall paintings, gas chromatography-mass spectrometry, infrared spectroscopy, proteinaceous binders, lipidic materials, gypsum, sulphatization.