Search

The consistent amount of sectilia fragments from the late Roman Villa of Aiano (4th-5th century AD)provides important insights on the study of the diffusion of opus sectile during the Late Roman period. The extent of the corpus of glass slabs, in particular, immediately suggests interesting perspectives on both the archaeological and technological issues. Thanks to cooperation between archaeologist, conservators, IT and scientists, an in-depth study of the repertory is in progress to provide important information about the technologies and the raw materials used to produce a number of selected samples. High-resolution images have been obtained via Reflectance Transformation Imaging (RTI) to better understand all the different phases characterizing the manufacture of the more complex slabs. Due to their flexibility and low analytical costs, portable and non-invasive analytical techniques provided a fast and quite accurate definition of the chemical and mineralogical properties of each sample and the first classification of a large number of slabs in compositional clusters. Portable X-Ray Fluorescence (p-XRF) and Fiber Optics Reflectance Spectroscopy (FORS) allowed a first definition of the chemical variability within the repertory and provided indications about both manufacturing and coloring techniques.

This work is focused on the conservation-restoration workscarried out on the Speranza, monumental sculpture of the 19th century placed inside the English Cemetery in Florence. The statue was covered by scattered greenish and black-grayish patinas mainly due to the biological growth. Optical microscopy, culture-based methods and CF-PAM imaging (Pulse Amplitude Modulated fluorometry of the Chlorophyll Fluorescence) were used to characterize the biodeteriogens, while the study of the stone material and of the decay layers was performed trough microstratigraphic observations and X-ray diffraction analyses. Laser cleaning trials were carried out using different wavelengths (1064 nm and 532 nm) and pulse durations. The optimization of the laser parameters was performed taking into account the results obtained from the stratigraphic layers observations of the thin cross-sections of the stone material and real time CF-PAM imaging of the phototrophic presence.The study allowed improving, planning and accomplishing of the laser cleaning treatment of the whole statue.

The surface texture of a stone represents a sensitive parameter in evaluating its conservation state. In monuments and sculptures, in fact, external agents continuously alter the appearance of stones, determining peculiar weathering patterns and modifying properties such as retention of water and particles, interaction with light, color, and finishing. The application of protective coatings also determines changes in surface appearance of a stone, usually evaluated and monitored by color change tests. Surface metrology methods offer the possibility to quantify these changes, evaluating the impact of external agents (natural, i.e. weathering, and artificially, i.e. protective coatings) on natural stones. In this research, we demonstrate the potential of surface areal measurements in describing the evolution of weathering processes and the effects of protective treatments on porous stone materials. The obtained results suggest that the extent of the modifications is related to the scale of observation (small- vs. large-scale undulations, i.e. roughness and waviness, respectively), with an overall increase of surface roughness as the weathering proceeds. Unexpectedly, coatings based on nanoparticle dispersions increase the topographic height parameters, due to the absence of a homogeneous film.