Reale R.,University of Rome La Sapienza |
Plattner S.H.,University of Rome La Sapienza |
Guida G.,Istituto Superiore per la Conservazione Ed Il Restauro |
Sammartino M.P.,University of Rome La Sapienza |
Visco G.,University of Rome La Sapienza
Chemistry Central Journal | Year: 2012
Although it is well known that any material degrades faster when exposed to an aggressive environment as well as that "aggressive" cannot be univocally defined as depending also on the chemical-physical characteristics of material, few researches on the identification of the most significant parameters influencing the corrosion of metallic object are available.A series of ancient coins, coming from the archaeological excavation of Palazzo Valentini (Rome) were collected together with soils, both near and far from them, and then analysed using different analytical techniques looking for a correlation between the corrosion products covering the coins and the chemical-physical soil characteristics. The content of soluble salts in the water-bearing stratum and surfacing in the archaeological site, was also measured.The obtained results stress the influence of alkaline soils on formation of patina. Cerussite, probably due to the circulation of water in layers rich in marble and plaster fragments, was the main corrosion product identified by X-ray Diffraction (XRD). Copper, lead and vanadium were found in soil surrounding coins. By measuring conductivity, pH and soluble salts content of the washing solutions from both coins and soils, we could easily separate coins coming from different stratigraphic units of the site.Data were treated by cluster and multivariate analysis, revealing a correlation between part of the coins and the nearby soil samples. © 2012 Reale et al.; licensee BioMed Central Ltd.
Ingo G.M.,CNR Institute of Nanostructured Materials |
Guida G.,Istituto Superiore per la Conservazione Ed Il Restauro |
Angelini E.,Polytechnic University of Turin |
Di Carlo G.,CNR Institute of Nanostructured Materials |
And 2 more authors.
Accounts of Chemical Research | Year: 2013
Fire gilding and silvering are age-old mercury-based processes used to coat thesurface of less precious substrates with thin layers of gold or silver. In ancient times, these methods were used to produce and decorate different types of artefacts, such as jewels, statues, amulets, and commonly-used objects. Gilders performed these processes not only to decorate objects but also to simulate the appearance of gold or silver, sometimes fraudulently. From a technological point of view, the aim of these workmen over 2000 years ago was to make the precious metal coatings as thin and adherent as possible. This was in order to save expensive metals and to improve the resistance to the wear caused by continued use and circulation.Without knowledge about the chemical-physical processes, the ancient crafts-men systematically manipulated these metals to create functional and decorative artistic objects. The mercury-based methods were also fraudulently used in ancient times to produce objects such as jewels and coins that looked like they were made of silver or gold but actually had a less precious core. These coins were minted by counterfeiters but also by the official issuing authorities. The latter was probably because of a lack of precious metals, reflecting periods of severe economic conditions.In this Account, we discuss some representative cases of gold- and silver-coatedobjects, focusing on unique and valuable Roman and Dark Ages period works of art, such as the St. Ambrogio's altar (825 AD), and commonly used objects. We carried out the investigations using surface analytical methods, such as selected area X-ray photoelectron spectroscopy and scanning electron microscopy combined with energy-dispersive spectroscopy. We used these methods to investigate the surface and subsurface chemical features of these important examples of art and technology, interpreting some aspects of the manufacturing methods and of disclosing degradation agents and mechanisms. These findings may contribute to cultural heritage preservation, thus extending the applicability of the surface analytical techniques. © 2013 American Chemical Society.
Cianchetta I.,University of Rome Tor Vergata |
Colantoni I.,University of Rome Tor Vergata |
Talarico F.,Istituto Superiore per la Conservazione Ed Il Restauro |
D'Acapito F.,CNR Institute of Materials |
And 4 more authors.
Journal of Analytical Atomic Spectrometry | Year: 2012
Smalt is a blue pigment used by many European artists in mural and easel paintings, mainly in the period from the XV to XVIII century. It is a potassium glass where cobalt is added to the glassy matrix to get the blue hue. The pigment deteriorates with age, changing its colour from an intense blue to a grey-yellowish hue, causing severe problems in the conservation of the paintings. In this study a set of specimens of smalt dispersed in linseed oil was prepared and artificially aged to simulate the progressive deterioration of the pigment in a painting on canvas. The artificially aged smalt specimens were compared with some samples of naturally aged smalt taken from a banner painted at the end of XV century by Luca Signorelli, the "Baptism of Jesus". A multi-technique approach, including SEM-EDX, spectro-colorimetry, X-ray absorption spectroscopy and ab initio calculations, was used to understand the progressive discoloration and to reveal its correlation with changes occurring in the pigment structure. © 2012 The Royal Society of Chemistry.
Di Tullio V.,CNR Methodological Chemistry Institute |
Proietti N.,CNR Methodological Chemistry Institute |
Gobbino M.,CNR Methodological Chemistry Institute |
Capitani D.,CNR Methodological Chemistry Institute |
And 4 more authors.
Analytical and Bioanalytical Chemistry | Year: 2010
As is well known, the deterioration of wall paintings due to the capillary rise of water through the walls is a very widespread problem. In this paper, a study of microclimate monitoring, unilateral nuclear magnetic resonance (NMR), and evanescent-field dielectrometry (EFD) was applied to map non-destructively, in situ, and in a quantitative way the distribution of the moisture in an ancient deteriorated wall painting of the eleventh century. Both unilateral NMR and EFD are quite new, fully portable, and non-destructive techniques, and their combination is absolutely new. The approach reported here is proposed as a new analytical protocol to afford the problem of mapping, non-destructively, the moisture in a deteriorated wall painting in a hypogeous building such as that of the second level of St. Clement Basilica, Rome (Italy), where the use of IR thermography is impaired due to the environmental conditions, and the gravimetric tests are forbidden due to the preciousness of the artifact. The moisture distribution was mapped at different depths, from the very first layers of the painted film to a depth of 2 cm. It has also been shown how the map obtained in the first layers of the artwork is affected by the environmental conditions typical of a hypogeous building, whereas the maps obtained at higher depths are representative of the moisture due to the capillary rise of water from the ground. The quantitative analysis of the moisture was performed by calibrating NMR and EFD signals with purposely prepared specimens. This study may be applied before and after performing any intervention aimed at restoring and improving the state of conservation of this type of artwork and reducing the dampness or extracting salts (driven by the variation of moisture content) and monitoring the effectiveness of the performed interventions during the time. This protocol is applicable to any type of porous material. © 2010 Springer-Verlag.
Golubic S.,Boston University |
Pietrini A.M.,Istituto Superiore per la Conservazione Ed Il Restauro |
Ricci S.,Istituto Superiore per la Conservazione Ed Il Restauro
International Biodeterioration and Biodegradation | Year: 2015
The Pyramid of Caius Cestius in Rome is a funerary architecture erected between 272 and 279 AD. The Pyramid is composed by a nucleus in opus caementicium covered by Luni marble slabs. The marble surface has been colonized by a biocoenosis of microorganisms. The most frequent alteration found on the surface of the stone is the grey-black microbial crust, consisting of three different systematic groups: coccoid and filamentous Cyanobacteria, belonging mainly to the genera Chroococccus, Gloeocapsa and Tolypothrix, and green algae often associated with microscopic fungi or lichenized. The present work is aimed to establish which taxa present in the black crust are epilithic and which ones are endolithic. The cyanobacterium Chroococcus lithophilus is the most abundant and frequent taxon in all the samples collected; its growth is epilithic, chasmoendolithic, cryptoendolithic and euendolithic. The resin embedding-casting technique allowed to define the traces produced by this cyanobacterium highlighting its ability to actively dig tunnels into the marble. The present paper is a significant contribution to the knowledge of the important role of C.lithophilus in the biodeterioration of stone monuments. © 2015 Elsevier Ltd.