Advanced NMR Methodologies in Cultural Heritage

NMR methodologies were applied and optimized to characterize and monitor Cultural Heritage. The various cases reported, clearly evidence how NMR is not confined to a few specific applications, but its use can be successfully extended to a wide number of different issues regarding Cultural Heritage. In fact NMR is a very powerful tool in the chemical characterization of materials allowing to shed light in the techniques used by artists, and in the knowledge of materials constituting the artifacts. Besides, knowledge of the causes of degradation of artifacts may be achieved by NMR through the study of the chemical-physical transformation and structural modifications due to the ageing. As a matter of fact, NMR investigation may also help in planning proper restoration works. Portable unilateral NMR was used to quantitatively map in a fully non-invasive way the moisture distribution in the fresco of St. Clement at Mass , a precious and ancient deteriorated wall painting, before and after an intervention to reduce the capillary raise of water through the wall. A multi-technique approach was used to study a decorated Egyptian wooden sarcophagus (XXV-XXVI dynasty, Third Intermediate Period), belonging to the Museo del Vicino Oriente of Sapienza University of Rome. Portable non-invasive unilateral NMR was applied to evaluate the conservation state of the sarcophagus and to perform an educated sampling to obtain a small amount of materials to be analyzed in laboratory. A further case regarded the study of the performances of water repellent treatments in porous stones. This study was aimed at answering general questions such as the penetration depth of a water-repellent treatment, its capability to impair the water absorption, how the presence of a treatment may change the open porosity available to the water, and how a treatment may affect the diffusion of water inside a porous structure. Finally, in the case of an ancient Nubian detached mural painting, relaxation times, NMR depth profiles and 13C CPMAS NMR spectroscopy were applied to explain the stratigraphy of the painting. These results provided useful information in planning a suitable restoration project.