Emma Cantisani

Pietra Serena: the stone of the Renaissance

Abstract The most frequently used material in Florentine Renaissance architecture was Pietra Serena, a sandstone that nowadays is found in a quite satisfactory state of conservation. The reason for this is that architects and stone cutters in the past made careful selections of the materials they employed. This conscientious picking out was very important because most sandstone layers have a composition that is not always suitable for assuring an acceptable durability. This paper deals with the mineralogical, chemical, petrographical and physical characteristics of the Pietra Serena sandstone quarried in the hills near Florence in order to verify what was affirmed by Vasari (1568), Tuscan painter, architect and historian of art of the 16th century, and other Tuscan naturalists regarding the quality of this sandstone. As a matter of fact, analyses demonstrate that the Pietra Serena sandstones quarried in the hills of Settignano (to the northeast of Florence) and in the Gonfolina area (Lastra a Signa, to the west of Florence), are composed of layers particularly rich in calcite present mainly as sparitic cement. This calcitic cement gives great durability to the stone as is demonstrated by the good state of conservation of some Florentine monuments realized with Pietra Serena.

Ceramic findings from the archaeological site at Aiano-Torraccia di Chiusi (Siena, Italy): a multi-analytical approach

In 2005, the remains of a Roman villa, dating from the early fourth to the sixth centuries ad, were discovered at the archaeological site of Aiano-Torraccia di Chiusi (Siena, Italy). After being abandoned in the sixth century ad, the complex was occupied by a group of Ostrogothic or Lombardic artisans in the period between the sixth and the seventh centuries ad. Many ceramic remains (coarse pottery and red slip ceramics) from the first to the seventh centuries ad have been discovered on this archaeological site. These findings have been analysed using different analytical techniques (optical microscopy (OM), X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscope-energy dispersive spectroscopy (SEM-EDS), attenuated total reflection Fourier transform infrared (ATR-FTIR), and micro-Raman in order to characterize the ceramic body, the coating, the temper, and to investigate the compositional relationship between the different kinds of ceramics. The use of different techniques on the same samples yielded information at different scales. OM and SEM-EDS yielded interesting information on the coarse pottery: the analyses performed on some minerals and rock fragments suggest that stone tesserae from the Roman villa (in the form of numerous marble fragments) were used in the production of this pottery. Bulk analyses (XRD and XRF) and subsequent micro-analyses (SEM-EDS, ATR-FTIR, and micro-Raman) of the red slip pottery revealed clear chemical, mineralogical and textural differences: some ceramics (the TCC sample group) typically have a Fe-enriched coating while others (the INGR sample group) present a clear difference in grain size but no chemical or mineralogical differences between the ceramic body and the coating.

Archaeometric study of natural hydraulic mortars: the case of the Late Roman Villa dell’Oratorio (Florence, Italy).

This paper shows the results of a multidisciplinary study carried out on the mortars from the Late Roman Villa dell’Oratorio (fourth-sixth ad), an aristocratic mansion built in the lower Valdarno (Florence, Italy). Thirty-one bedding mortar and plaster samples were analysed through optical microscopy, thermogravimetric analysis, X-ray powder diffraction and scanning electron microscopy with energy-dispersive X-ray spectroscopy for determining the chemical, mineralogical and petrographic characteristics, while their main physical properties were measured by geotechnical procedures. The collected data indicates that the analysed mortars are made up of very fine to coarse river sand aggregate mixed with white to yellowish-white natural hydraulic lime binder mainly consisting of mixtures of prevailing calcite and hydraulic compounds. With regard to the origin of the raw materials, the aggregates were recognized to be selected Arno river sands, and the binders are the burning product of a local marly limestone (ex Alberese). Therefore, the mortars of the Late Roman Villa dell’Oratorio are one of the first uses of natural hydraulic lime in the lower Valdarno.

Contemporary artists' spinel pigments: Non-invasive characterization by means of electronic spectroscopy

The identification of artistic materials represents a fundamental step in supporting the conservation of cultural heritage objects. The importance of their appropriate characterization is particularly relevant in modern-contemporary art, since they could be affected by the occurrence of rapid changes in chemical formulation over time. This paper focuses on an investigation of a series of contemporary blue-green commercial acrylic paints constituted of spinel pigments, using non-invasive spectroscopic techniques. The spectroscopic and color measurements obtained make it possible to characterize the acrylic paints under investigation and to compare the results obtained with those reported in the literature and in spectral databases. To be more precise, the proposed UV-vis-NIR reflectance spectroscopic technique was sensitive enough to characterize the acrylic paints according to their d-d ligand field and the charge transfer (CT) electronic transitions involved in the spinel structures. In addition, an overview of this class of inorganic pigments is also given.

The ancient gypsum mortars of the historical façades in the city center of Valencia (Spain)

In the historical centre of Valencia (Spain), the brick facades of the residential buildings which were built or modified in the end of the XVIII th century and the beginning of the XX th century have been protected and decorated with continuous renderings. According to the constructive tradition, the renderings had to be made with lime mortars, but the recent studies allowed to know their real nature: they are gypsum mortars. The main aim of the study has been to know the nature and the technical aspects of the historical renderings of the facades of the centre of Valencia, in order to discover their secrets from a theoretical and experimental point of view. Therefore, together with the examination of bibliographical sources, several samples of the historical mortars have been collected from renderings. The analytical results confirm that the great majority of samples are composed by gypsum mortars, with different degrees of purity and a variable amount of aggregate and lime. Some samples are mixed mortars (gypsum and lime mortars), but there are also examples of pure lime mortars probably indicating a change in the constructive tradition of the city in a historical moment as testified by the presence of buildings with brick walls bonded with lime mortar and gypsum mortars in the rendering. This fact supposes a conscious application of the gypsum in exteriors and the existence of a specific ancient technique. Moreover the analysis of the surfaces of renderings characterized by a specific finishing and several layers of painting, allows us to confirm that organic substances have been applied in order to protect the gypsum mortars from the inclemency of the weather. Definitively, the characterization of the gypsum mortars that cover the historical facades of the centre of Valencia allowed us to discover a particular and distinguishing aspect of the constructive tradition of the city that must be protected and valued in order to achieve its preservation.

A multi-analytical approach for the characterization of wall painting materials on contemporary buildings

Samples from Keith Harings wall painting of the Necker Children Hospital in Paris were studied by a multi-analytical protocol. X-ray fluorescence (XRF), powder X-ray diffraction (XRDP), Electron microscope (SEM-EDS), Infrared and Raman spectroscopy (μ-FT-IR and μ-Raman) measurements were performed in order to characterize the materials and to identify the art technique used to produce this contemporary work. Materials from the mural suffered from severe detachments of materials and several fragments were found on the ground beneath. Some of these fragments, which were representative of the whole palette and stratigraphic sequence, were collected and studied. The fragments were sufficiently large to enable non-invasive measurements to be performed in order to characterize the materials. A comparison of the data of the techniques applied revealed that Harings palette was composed of organic pigments such as Naphtol red, phthalocyanine blue and green and Hansa yellow, in accordance with those used previously by the artist in other painted murals.

Restoration of a Sandstone Facade: From the Project to the Monitoring

This work describes the restoration of a facade of an historical building, constructed from typical local sandstone, characterized by different subsequent decay phenomena and subjected in the past to a conservation treatment. The sandstone was characterized, the quarry of provenance was identified, and the causes of the different decay phenomena were investigated. Potential commercial products for the restoration were tested first in the laboratory, then in situ selected products were applied and the effectiveness of treatment was subsequently monitored. Analytical methodologies such as x-ray diffraction (XRD), observation of thin sections under polarized microscope (OM), Fourier transform infrared spectroscopy (FT-IR), micro-Raman spectroscopy, and water absorption tests were employed in the laboratory, while nondestructive tests, performed with portable instrumentation such as colorimeter and sponge contact, were carried out in situ.

Innovative application of portable X-ray fluorescence (XRF) to identify Göktepe white marble artifacts

An efficient and non-destructive method to classify white marble artifacts by using a hand-held, portable XRF analyzer (pXRF) is here reported. The identification is based on the uniquely high strontium content of this marble and has been verified by testing 32 artifacts, most of which had already been provenanced, using conventional micro-destructive analyses. Besides strontium, other potential provenance indicators, such as manganese and iron, were analyzed and their concentration values obtained after empirical calibration of the instrument by using 17 quarry samples of known composition. The results show that Göktepe/non-Göktepe discrimination is almost always possible (30 artifacts) and that additional analyses are required only when the Sr value is at the lower edge of the Göktepe field (2 artifacts). The success of the method, however, resides in the particular composition relative to trace elements of Göktepe and is not easily extended to other marble varieties. Main reasons are related to insufficient accuracy at low concentration values, intrinsic trace variability of marble artifacts, surface effects that may produce not representative results. Interest in the method therefore is tightly linked to the exceptional importance of Göktepe as a sculptural marble, in which case, detailed data, obtained with a fast and totally non-destructive method, may provide relevant information concerning chronology, workshops, and places of production of the artifacts.

Painted Fiberglass-Reinforced Contemporary Sculpture: Investigating Composite Materials, Techniques and Conservation Using a Multi-Analytical Approach

A multi-analytical approach was used to study the constituent materials, manufacturing technique, and state of conservation of a contemporary sculpture. This sculpture, entitled Nuredduna, was created by Aligi Sassu in 1995 and is located in the “Bellariva garden” in Florence (Italy). Fourier transform infrared spectroscopy (FT-IR), optical and electronic microscopy (OM and SEM-EDS), X-ray diffraction (XRD), and portable X-ray fluorescence (XRF) highlighted the multi-layered structure of the statue: fiberglass and an overlay of different layers (gel coat) applied with an unsaturated polyester resin added with aggregate materials and bromine compounds. A top-coat in acrylic black varnish, used as a finish, was also found. The combination of these materials with their different compositions, environmental impact, and even vandalism have negatively affected the state of conservation of Nuredduna, causing the loss of strata in its lower parts (legs and feet).

Petrographic study of lime-based mortars and carbonate incrustation processes of mural paintings in Roman catacombs.

The Roman catacombs of St Tecla, Domitilla and St Mark, Marcellian and Damasus located south of the centre of Rome were extensively investigated in this research, to study the technology of lime-based mortars and techniques of mural painting used by the ancient fossori to execute the decorated surfaces. The integrated minero-petrographic and microchemical approach exploited here and including thin section observations, X-ray diffraction analyses and diamond anvil cell FT-IR spectroscopy, provided evidence of the technical variability in terms of materials, mortar stratigraphy and application methods. Scientific data suggest potential environmental and operational explanations for certain technical solutions used by fossori in the second half of 4 th - early 5 th century AD. We also discuss a wide range of surface carbonate crystallisations, which represent one of the alteration processes affecting the inner surfaces in Roman catacombs, with direct impacts on the preservation and promotion of the painted heritage. The petrographic examination of the textural properties confirms that the morphologies with which the crystallisations occur depend on the hypogean microclimate of exposure. Strategies of preventive conservation should be based on long-term monitoring of the critical microclimate parameters, coupled with periodic diagnostics of the surfaces.