Folding fans are complex artifacts that include a variety of materials that have been processed and assembled to produce very small supports and decorations. Unfortunately, due to their fragility, as well as the lack of suitable non-invasive and non-destructive analytical techniques, the constituent materials and stratigraphies of historic folding fans have been rarely studied so far. This work aimed to develop and demonstrate a suitable analytical methodology for characterizing a French fan and to establish manufacturing techniques employed in its production. To this goal, advanced non-destructive and micro-destructive photonic techniques were employed to gather compositional and processing information with a non-invasive approach. This artifact provided the opportunity to evaluate the potential of different techniques: Portable Raman spectroscopy (with excitation at 785 nm) was used for identifying the pigments of the painted leaves and the gemstones; particle-induced X-ray emission (PIXE) and Rutherford backscattering spectrometry (RBS) were employed to quantify metal alloy compositions and stratigraphy of the decorations; portable laser-induced breakdown spectroscopy (LIBS) allowed the measurement of elemental depth profiles of metal decorations which were congruent with those provided by PIXE. Finally, additional stratigraphic information on metal decorations, in terms of gold distribution and state of conservation, was achieved through selective laser ablation.

Two painted cubicles of the catacombs of Santa Tecla and Domitilla in Rome were analytically characterized and then restored by means of an overall application of laser ablation treatments. This is the first application of laser ablation in the conservation of wall paintings in hypogean environments in which the main cause of deterioration is calcareous precipitations associated with the karst phenomenon, which cemented carbonaceous and tuff microfragment deposits of the past. The alterations found in the two sites are representative of typical conservation problems encountered in the Early Christian paintings of Roman catacombs. This makes the present approach for unveiling and preserving such a unique cultural asset of general interest. Its application in the cubicle of Santa Tecla allowed the unveiling of the early icons of the Apostle Saints John, Paul, Andrew and Peter, while in that of Domitilla, expressive scenes from the New Testament were surprisingly recovered.

The control of biodeterioration encompasses the operations undertaken to eliminate the biological growth and, possibly, to delay a new colonization. The current attitude is generally oriented toward its planned removal whenever it causes an objective damage and/or structural impairments to the substratum. The English Cemetery, located in the centre of Florence, offers interesting features for a research focused on the removal of biofilms and lichens growing on stone surfaces of some tombs. The study compared the efficacy of two methods based on physical approach (mechanical cleaning with a brush and microwave heating) with a chemical approach using biocide ROCIMA™ 103 to remove biofilms and lichens from each tombstone. The research, focusing on methodologies with low impact for the environment, tested the efficacy of an innovative portable system that produces localized microwave heating. Its great advantage lays on lack of the potential risks associated with the irreversible application of microbicides. The assessment of the treatments' efficacy was carried out monitoring the chlorophyll a fluorescence's parameters, informative on the vitality and stress responses of photosynthetic organisms. The long-term monitoring of the recolonization after the treatments was performed for five years. The mechanical cleaning eliminated the superficial layer of biofilms and lichens but not the cells within the stones. The biocide was efficient in killing the biological growth; almost no recolonization was observed after about five years. The innovative microwave treatment was effective on biofilms and lichens, eliminating also cells present in the bulk of the substrata, but recolonization was observed after 15 months. This suggests that, dopo treatment aggiungere virgola the microwave treatment should be performed more frequently than biocide treatments yet guaranteeing lower impact on the environment.

Here we report the first extensive validation study of laser removal of biodeteriogens from marble. The work was carried out on the Speranza, monumental sculpture of the 19th century placed inside the English Cemetery in Florence. The statue was covered by diffuse greenish and black-grayish species due to the biological growth, a mix of cyanobacteria, algae and fungi classified as biofilm. Optical microscopy, culture-based methods and CF-PAM imaging (Pulse Amplitude Modulated fluorometry of the Chlorophyll Fluorescence) were used to characterize the biodeteriogens. Laser technique was proposed as an efficient alternative for the traditional cleaning methodologies. Preliminary trials were performed using different wavelengths and pulse durations. The optimization of the laser parameters was performed considering the results obtained from the stratigraphic layers observations of the 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. (C) 2018 Elsevier Ltd. All rights reserved.

The periodical removal of biodeteriogens is a fundamental need for the preservation of outdoor stone cultural heritage, which is stimulating significant efforts toward the development of low-impact conservation strategies. In the present work, the potential of laser removal of Verrucaria nigrescens Pers. from Carrara marble and the evaluation of the associated biocide effect on the organism residues embedded in the surface texture and through the outer porosities of the stone substrate were investigated. The fundamental wavelength of Nd:YAG laser (1,064 nm), commonly used in stone cleaning, and its second harmonic (532 nm) were comparatively tested. The phenomenology of laser treatments carried out in different irradiation conditions was characterized using optical, epifluorescence, and electron microscopes along with chlorophyll fluorescence with pulsed amplitude-modulated imaging. The results achieved show that 532 nm can provide significant advantages with respect to 1,064 nm. The potential of the latter against the biodeteriogens appears rather limited because of the low optical absorption, whereas the former can allow effective and practicable laser treatments, which disclose a significant application perspective.

In this work, the potential applications of surface laser removal of biological crusts from Carrara marble artefacts and in-depth microwave selective heating for treatment of possible endolithic growths have been evaluated. The investigations were carried out on seriously deteriorated marble fragments from the monumental tombs of the English Cemetery in Florence, Italy. The second harmonic (532 nm) of a Q-switched Nd:YAG laser was used for cleaning while a microwave system emitting at 2.45 GHz was tested for in-depth sterilization. As is well known, microwaves are strongly absorbed by water via dipolar energy dissipation, which permits selective heating of endolithic organisms. The effects of laser and microwave treatments were characterized using scanning electron microscopy (SEM) along with chlorophyll fluorescence with pulsed amplitude modulated imaging. The latter has allowed the quantification of the impairment effects to photosystem II of epilithic phototrophic organism residues by mapping the maximum quantum yield, while the damage to endolithic growths was evaluated by means of SEM following osmium tetroxide staining of cytoplasmic lipids. The results provide an early picture of the development and application perspectives of the combined laser and microwave treatments in the conservation of biodeteriorated stone artefacts.

Here, we investigated the potential of laser removal of iron-rich dark films from weathered granite substrates, which represents a very difficult conservation problem because of the polymineralic nature of the stone and of its complex deterioration mechanisms. As often occurs, biotite was the most critical component because of its high optical absorption, low melting temperature, and pronounced cleavage, which required a careful control of the photothermal and photomechanical effects to optimize the selective ablation of the mentioned unwanted dark film. Different pulse durations and wavelengths Nd:YAG lasers were tested and optimal irradiation conditions were determined through thorough analytical characterisations. Besides addressing a specific conservation problem, the present work provides information of general valence in laser uncovering of encrusted granite.

The present work was aimed at characterising the materials and assessing the state of conservation of the ‘Adorazione dei Magi’, a wooden panel painted by Bartolo di Fredi in the second half of fourteenth century. To this goal, innovative non-destructive investigation techniques such as portable Raman spectroscopy, visible reflectance spectroscopy and unilateral nuclear magnetic resonance, were used in situ in order to achieve surface and bulk compositional data. The former allowed the identification of the artist's palette including cinnabar, red ochre, minium, carbon black, lead white, ultramarine blue, malachite and phthalocyanine green, while the latter provided information on the stratigraphic structure and state of conservation of the wooden panel.

A systematic study on the use of Chlorophyll Fluorescence (CF) imaging in Pulsed Amplitude Modulated (PAM) for assessing viability changes of biodeteriogen on stone artifacts has been carried out. The experimentation has been performed on different phototrophic organisms of gravestone slabs from the monumental British Cemetery of Florence (Italy). Since the viability of these organisms and then their chlorophyll fluorescence emission is strongly dependent on the environmental conditions, a preliminary study on the effects of local patterns during the season was carried out. The trend of the fluorescence quantum yield (QY(max)) at different dark adapted times in different periods of the year was determined. The results achieved in our work proves the effectiveness of the CF-PAM imaging for in situ lichen characterizations in conservation studies and defines an optimized application protocol.

The present work focuses on the potential of 3D digital microscopy for assessing micro-morphological features during laser cleaning treatments of artworks. This application requires preliminary optimization studies aimed at defining operative irradiation parameters and practicable degree of cleaning, as well as in situ diagnostic assessments during the restoration work. To this goal, we developed and tested a dedicated 3D digital microscope by implementing the "shape-from-focus" technique. The significant potential of this instrument, which provides textural and chromatic information, was proven for the phenomenological characterization of black crust removal from stones, earthy concretion from bronzes and dark varnish from easel paintings. Comparative measurements using 3D digital microscopy and contact microprofilometry were performed after laser cleaning tests of prepared samples, genuine archaeological bronze artefacts and a stone sculptural element from Florence's Dome. The results achieved demonstrate the effectiveness and reliability of the novel approach and the advantages it provides with respect to alternative techniques, which will allow the methods to be used in the wider restoration community.

In the present work the application of laser cleaning in the conservation of cultural assets is reviewed and some further developments on the interpretation of the associated laser-material interaction regimes are reported. Both the state of the art and new insights mainly focus on systematic approaches addressed to the solution of representative cleaning problems, including stone and metal artifacts along with wall and easel paintings. The innovative part is entirely dedicated to the extension of the application perspective of the Nd:YAG lasers by exploiting the significant versatility provided by their different pulse durations. Besides extensively discussing the specific conservation and physical problems involved in stone and metal cleaning, a significant effort was also made to explore the application potential for wall and easel paintings. The study of the latter was confined to preliminary irradiation tests carried out on prepared samples. We characterized the ablation phenomenology, optical properties, and photomechanical generation associated with the irradiation of optically absorbing varnishes using pulse durations of 10 and 120 ns. Further results concern the nature of the well-known problem of the yellowish appearance in stone cleaning, removal of biological growths and graffiti from stones, cleaning of bronze and iron artifacts and related aspects of laser conversion of unstable minerals, removal of calcareous stratification from wall paintings, and other features.

Innovative noninvasive material analysis techniques are applied to determine archaeometallurgical characteristics of copper-alloy coins from Florence's National Museum of Archaeology. Three supposedly authentic Roman coins and three hypothetically fraudolent imitations are thoroughly investigated using laser-induced plasma spectroscopy and time of flight neutron diffraction along with 3D videomicroscopy and electron microscopy. Material analyses are aimed at collecting data allowing for objective discrimination between genuine Roman productions and late fakes. The results show the mentioned techniques provide quantitative compositional and textural data, which are strictly related to the manufacturing processes and aging of copper alloys.