Digitalization techniques, such as photogrammetry (PG), are attracting the interest of experts in the cultural heritage field, as they enable the creation of three-dimensional virtual replicas of historical artifacts with 2D digital images. Indeed, PG allows for acquiring data regarding the overall appearance of an artifact, its geometry, and its texture. Furthermore, among several image-based techniques exploited for the conservation of works of art, multispectral imaging (MSI) finds great application in the study of the materials of historical items, taking advantage of the different responses of materials when exposed to specific wavelengths. Despite their great usefulness, PG and MSI are often used as separate tools. Integrating radiometric and geometrical data can notably expand the information carried by a 3D model. Therefore, this paper presents a novel research methodology that enables the acquisition of multispectral 3D models, combining the outcomes of PG and MSI (Visible (VIS), Ultraviolet-induced Visible Luminescence (UVL), Ultraviolet-Reflected (UVR), and Ultraviolet-Reflected False Color (UVR-FC) imaging) in a single coordinate system, using an affordable tunable set-up and open-source software. The approach has been employed for the study of two wooden artifacts from the Museo Egizio di Torino to investigate the materials present on the surface and provide information that could support the design of suitable conservation treatments.

This paper describes a portable low-cost device for performing Electrochemical Impedance Spectroscopy (EIS) measurements which is based on an off-the-shelf TeensyDuino. The instrument does not make use of other components like operational amplifiers so it can be readily set up by anyone having a Teensy device and some resistors. Teensy 3.2, 3.5 and 3.6 can be used to realize the EIS system. The instrument can measure the impedance in the frequency range from 0.01 Hz to 50000 Hz and by selecting the shunt resistor it can be adapted to different impedance values. No special instrumentation is required for the system calibration. The proposed system uncertainty is of less than 5% for an impedance of up to 50 Ωk, a value which is lower than the usual intrinsic uncertainty of most of corrosion experiments.

This paper presents a long-term in-situ campaign to monitor contemporary bronze statuary exposed outdoors. The case study relates to the characterisation of three sculptures belonging to the Gori Art Collection, located in the Fattoria di Celle: ‘Cavaliere’ and ‘Miracolo – Composizione’ by Marino Marini and ‘Due forme o due ombre n°2’ by Luciano Minguzzi. The overall conservation state of the sculptures was investigated by means of a multi-analytical and non-invasive approach, involving different techniques. Three-dimensional photogrammetry was performed to fully document the artworks. The chemical and microstructural features of the corrosion patinas were then characterised through X-ray fluorescence and Raman spectroscopy. In addition, the stability and the protective effectiveness of the corrosion products were assessed by electrochemical impedance spectroscopy. Thanks to the combined use of these specific techniques, the information extracted through the different analyses could be correlated with each other and with the exposure conditions. The different corrosion products were identified as being primarily copper sulphates and phosphates, and they were correlated with the different microclimate conditions related to their location on the statues. The information gathered from the presented multi-analytical approach represents the fundamental knowledge required to develop a tailored conservation project to assure the long-lasting preservation of these artworks.

Recent progress in the realm of imaging technologies has swiftly disseminated fresh methodologies for representing objects, broadening the horizons for scholars such as art historians, archaeologists, conservators, and conservation scientists. Reflectance Transformation Imaging (RTI) and three-dimensional (3D) modeling via Structure from Motion (SfM) have rapidly gained popularity and are being employed by a wide range of users, expanding the possibilities for understanding objects of material cultural heritage from different perspectives. This paper explores the outcomes achieved through the application of these techniques to gain deeper insights into the surface of a bas-relief within a confined space. This methodology enhanced our understanding of the original sandstone surfaces of the bas-relief by integrating RTI and 3D visualization, thereby acquiring a novel investigative tool with enhanced illumination possibilities. A data fusion approach is proposed using photogrammetry to produce a Virtual RTI (V-RTI). In the case study reported in this paper, focusing on one inner wall of the chapel of Ellesiya at the Museo Egizio of Turin, V-RTI was employed to obtain useful surface information in a context where conventional RTI would have been impossible to achieve. Finally, the study compares the different techniques through direct qualitative and quantitative analysis, highlighting possible future developments from both instrumental and methodological points of view.

In this paper, a study of the corrosion products formed on archaeological bronze artefacts excavated in Tharros (Sardinia, Italy) is presented. The investigation was carried out by means of the combination of different analytical techniques, including optical microscopy, micro-Raman spectroscopy (µ-RS), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy and X-ray diffraction. The artefacts under study are three bronze coins from the Phoenician–Punic period that are deeply corroded due to the chloride-rich soil of the Tharros excavation site. µ-Raman spectroscopy was chosen to investigate the corroded surfaces of the artefacts because it is a non-destructive technique, it has high spatial resolution, and it makes it possible to discriminate between polymorphs and correlate colour and chemical composition. Through µ-RS, it was possible to identify different mineralogical phases and different polymorphs, such as cuprite (Cu2O), copper trihydroxychloride [Cu2Cl(OH)3] polymorphs, hydroxy lead chloride laurionite [PbCl(OH)] and calcium carbonate polymorph aragonite. The experimental findings highlight that micro-Raman spectroscopy can be used to provide further knowledge regarding the environmental factors that may cause the degradation of archaeological bronzes in soil.