A Diagnostic Analysis of an Outdoor Fresco: the Case of "santa Maria Dei Battuti" of the Conegliano Cathedral

Abstract

During recent decades, the Santa Maria dei Battuti facade of the Conegliano Cathedral, painted by Ludovico Pozzoferrato in the XVI century, has been subjected to frequent intervention works to slow down a sharp increase in the degradation processes. According to previous investigations carried out respectively in 1989 and 2003 preliminary to the last two conservation works it was found that a sulphating process of fresco paintings was taking place. In addition a widespread presence of whitening of the painting surface was observed. At the end of the work it was decided to make some periodic checks on the wall paintings surface in order to establish if the decay products were increasing. In addition to the traditional laboratory analytical methods of analysis for the determination of soluble salts it was decided to map the gypsum presence on the wall paintings surface by using XRF spectroscopy. Making use of a transportable EDXRF system more than 350 analysis were carried out to check the full surface of the facade. Besides the degradation processes, the palette and painting techniques of the author were established. At the end of the scientific campaign, an up to now unique working protocol was established. The full facade was inspected and mapped out in all of its degradation processes. The result is a very powerful documentation of the state of the art of the fresco surface. This project was fulfilled with a strong synergy among scientists, art historians and restorers. Together with the results of the "Santa Maria dei Battuti" facade, in this memoir the working protocol established is explained. INTRODUCTION The diagnostic project we present in this memoir had the goal to verify the conservation state of the wall paintings after the restoration of 2003. The control followed the criteria: • General and detailed photographic documentation on the full area of the wall paintings to describe and register the present state. • Photo comparison with the documentation collected immediately after the restoration operation. • Mapping of the alteration with visual inspection. • Measurement made with a portable XRF system, of the sulphur concentration in various parts of the surface. The presence of the sulphur can be a precise indication of a sulphating process originating from sulphur dioxide. • Measurements using a portable XRF system, of the distribution concentration of barium ascribed to the consolidating treatment fulfilled with barium hydroxide. • Measurement of water absorbance parameters on the surface of the wall. • Stratigraphy studies of micro samples on the most significant pigments and comparison with the results of the non destructive measurements carried out with portable XRF. • Soluble salts measurements in whitening surface areas. THE FACADE OF THE DOME OF CONEGLIANO The Dome of Conegliano was built in successive stages starting from 1345 and modified up to the 60's of the XX century. It is an example of great complexity. The facade is, in fact, 1 9th International Conference on NDT of Art, Jerusalem Israel, 25-30 May 2008 For more papers of this publication click: www.ndt.net/search/docs.php3?MainSource=65

2 Figures and Tables

Cite this paper

@inproceedings{Fassina2008ADA, title={A Diagnostic Analysis of an Outdoor Fresco: the Case of "santa Maria Dei Battuti" of the Conegliano Cathedral}, author={Vasco Fassina and Marta Mazza and Ilaria Carocci and Stefano Ridolfi}, year={2008} }