Provenance study of ancient Iranian luster pottery using PIXE multivariate statistical analysis

Although luster potteries are frequently excavated at archeological sites in Iran, a thorough scientific study of their provenance has not yet been performed. In this work, 43 pieces of Iranian luster pottery (bowl, dish and tile) excavated from Rayy, Kashan, Maragheh, Alamoot, Takht-i-Sulayman and Jiroft were analyzed in order to investigate their origin. The luster shards which belong to Seljuks and Il-Khanids dynasties (12th–13th centuries) were analyzed using proton induced X-ray emission (PIXE) technique. To classify the fragments according to their location and origin, principal component analysis (PCA) and hierarchical cluster analysis (HCA) were applied to the chemical compositions of the body of the shards. We were able to classify the samples into three distinct groups using PIXE.     

Experimental investigations of stained paper documents cleaned by the Nd:YAG laser pulses

The historical paper samples from XIII–XIX c. are characterised by means of techniques of the optical spectroscopy. The influence of pulsed laser cleaning by means of the Q-switched Nd:YAG laser at 532 nm on the spectra and also cleaning results of stained paper documents are reported and considered. In the absorption spectra, the minima around 280 and 370 nm are identified and luminescence reveals a characteristic band centred around 430 nm. The laser cleaning diagnosed by the recording of the LIF spectra with 266 nm excitation shows a profile of increasing intensity and preserved structure. The LIPS spectra reveal sharp emission lines recorded at 612.5, 644.2, 646.5, 671, 714.9, 720.2 nm (Ca I), 589.4, 616.4, 780 nm (Na I), and 766.5: 769.9 nm (Mg I) which are ascribed to the surface contaminations. The intensity decrease of these peaks is in accordance with successive laser pulses and monitors the cleaning progress of the stained paper.     

PIXE analysis of V–XVI century glasses from the archaeological site of San Martino di Ovaro (Italy)

The analysis of 42 glass fragments, excavated in the Italian archaeological site of San Martino di Ovaro, that includes a palaeochristian church dated from the V–VI century, has been done using the PIXE technique in a fully non-destructive way without any sample preparation. The results have been validated with a set of standards and using PIGE data acquired in parallel. The data of 29 of the 42 glasses indicate that an earlier group of samples (window sheets and sacred vessels, dated from the V–VI century) is typical of the Roman technology and can be associated to a Levantine production of natron glass. The blue glasses of this group are all window sheets coloured with cobalt, probably from the Near-East. The remaining heterogeneous samples (lamps, necklaces, cups) are related by their type and function and by the different compositions, to the later use of the site as a market place. The natron glasses of San Martino di Ovaro provide new data for the understanding of the changes in the glass industry in North-eastern Italy and nearby regions across the fall of the Western Roman Empire.     

Approach to environmental risk analysis for the main monuments in a historical city

The analysis of environmental risk in historical cities facilitates the development of conservation strategies that can minimize the deterioration of historical heritage sites. Risk maps built with GIS software provide information about the probability of the main hazards in a region, and is a very useful tool to identify, evaluate and prioritize the restoration budget of a city in order to manage preventive conservation. In this paper, new methodologies are applied based on the vulnerability matrix and its relationship with static and structural factors, climate conditions, air quality and social agents. This technique has some obvious advantages in the application of risk analysis for cultural heritage conservation, such as the capability of simultaneous risk assessment and geographical references. The vulnerability study implies an on-site diagnosis analysis and requires an adapted protocol for archaeological heritage. The validation of this methodology was carried out in the historical town of Merida (Spain) with a GIS application (ArcGIS software), where the main monuments of this UNESCO World Heritage site were studied.     

Chemical cleaning of soiled deposits and encrustations on archaeological glass: A diagnostic and practical study

The aim of this study is practically to establish a chemical strategy for cleaning soiled deposits and encrustations on archaeological glasses. Investigations were performed on a series of Roman glass samples (Fragments and complete objects) coming from different excavations in northern Jordan. The chemical composition of the glass samples was determined by X-ray fluorescence spectrometer (XRF) analysis technique, whereas X-ray powder diffractometer (XRD) and Energy dispersive X-ray (EDX) methods were used to determine the mineralogical and elemental composition of the soiled deposits and encrustations on the glass surfaces. Furthermore, Scanning Electron Microscopy (SEM) examination and optical assessment were performed before and after cleaning glass. The glass samples were subjected to different cleaning protocols such as Calgon (Sodium hexametaphosphate), ethylenediaminetetraacetic acid (EDTA) at different pH values, citric and tartaric acids and piranha solution (a solution of sulphuric acid and hydrogen peroxide). Sepiolite poultices soaked by chemical agents were the most suitable methods used for applying chemical solutions on the glass surface. It can be concluded that EDTA is generally accepted as the most effective chelating agents recommended for cleaning encrustations on durable glass. It was more effective and safe at neutral pH with low concentrations around 5 to 7%. The calcareous crusts can safely be removed by using a piranha solution. Citric and tartaric acids appeared a moderate efficiency on cleaning weathered and stable glass. Calgon has a tendency to damage corroded and iridescent surfaces, and should be avoided when cleaning weathered glass.     

Spectroscopic and chromatographic studies of sculptural polychromy in the Zhongshan Grottoes (R.P.C.)

The sculptural polychromy in the Zhongshan Grottoes, sited in northwest China, has been investigated in terms of chemical composition of employed materials and pigments, state of conservation and painting technique. Raman analysis, Fourier-transform infrared analysis, analysis through energy-dispersive X-ray spectrometry coupled to scanning electron microscopy and pyrolysis coupled to gas chromatography and mass spectrometry were applied. Six analyzed samples showed silicates and kaolin as main components of the ground layers. Also lead white has been found in these layers. Minium, red-earth and mercury sulfide are the red pigments detected in the polychromy. A mixed use of malachite and atacamite has been detected in three green samples. Optical characteristics of atacamite and malachite found in the samples indicate a synthetic origin. The presence of a synthetic organic pigment such as phthalocyanine chlorinated pigment was also revealed. Ultramarine blue pigment, obtained by purification of lapis lazuli, has been detected in the blue sample. As for the binders used, fatty materials and siccative oil were found.     

Modelling and analysis of a basilica under earthquake loading

In this paper a basilica-type church is analysed in order to assess its structural behaviour and seismic vulnerability. For this purpose, an effective two-step procedure has been used, consisting of: (a) 3D static and dynamic linear analyses of the structural complex, and (b) 2D nonlinear push-over analysis of the single macro-elements. The results obtained through push-over analyses have been compared to the collapse loads derived from limit analysis, proving the ability of finite element (F.E.) nonlinear model to provide reliable simulation of the actual response of masonry elements. Then, the strength demand on each single structural macro-elements, resulting from the 3D linear analyses, has been compared to the macro-element ultimate strength capacity. The comparison demand vs. capacity has been carried out for all transversal and longitudinal macro-elements of the church, allowing a direct, though approximate, assessment of the seismic safety level of the church. The comparison demand vs. capacity confirms the susceptibility of this type of buildings to extensive damage and possibly to collapse, as frequently observed. The insertion of rigid diaphragms, which represents a widely used retrofit technique, has also been investigated; such intervention triggers concentration of strength demand in the stiffest macro-elements, so that the seismic capacity of the building is not necessarily increased.     

Using contingent valuation and cost-benefit analysis to design a policy for restoring cultural heritage

Historical heritage is proving an ideal field to apply contingent valuation for estimating individual as well as collective preferences as goods tend to be non-market and publicly owned. Yet despite this, findings are seldom used to draw up cultural policies or assess cultural heritage related projects. The current paper thus posits an approach which merges contingent valuation and cost-benefit analysis to design a cultural policy aimed at restoring the urban cultural heritage of the city of Valdivia (Chile). Contingent valuation is used to estimate the expected benefits from heritage for both local residents and tourists visiting Valdivia. We then apply cost-benefit analysis to the findings to evaluate a project to restore the historical ensemble through a non-profit foundation. The originality of the proposal lies in its merging the two approaches and may prove appealing to developing countries in which much of the heritage has been neglected and left to deteriorate, and where few or no resources have been devoted and a lack of effective institutional schemes to address the situation is evident.     

Efflorescence on thin sections of calcareous stones

Limestone and marble, still frequently used as building materials are especially vulnerable to the destructive effects of efflorescence. The effect of interaction between five different calcareous stones and corrosive atmospheres has been investigated. A novel technique of stone degradation analysis has been used where thin sections of fresh stone materials were exposed in a corrosion chamber under controlled conditions (temperature, relative humidity (RH), SO₂ and NO₂ concentration). Following 1-week’s exposure; observations of the initial crystallisation were studied by light microscopy, scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD). The results obtained from the surface analysis clearly showed sulphation of the samples and formation of gypsum. Observations of the initial corrosion indicated differences in the location of efflorescence and its shape among and within the samples. The mineralogy, grain shape and size, mineral defects and existence of cracks and pores, all influenced the substrate’s reactivity. The most vulnerable areas and the places where the corrosion started on the calcitic stones were the triple grain junctions followed by grain boundaries, and on the dolomitic marble cracks and pores.     

A study on a set of drawings by Parmigianino: integration of art-historical analysis with imaging spectroscopy

Due to the extreme fragility of paper-based artefacts, few techniques are available for scientific investigation and characterisation of ancient drawings or paper-based artefacts. Image reflectance spectroscopy represents an almost unique tool for scientific analysis on precious drawings, for which even micro-invasive techniques of analysis cannot be used. Indeed, beside the high fragility of the support, drawings and graphical works are typically characterised by a very limited number of artistic materials, which in principle could give information on the work of art. In this paper an interdisciplinary study on a set of drawings by Parmigianino (1503–1540), selected from the collection of the Uffizi Gallery in Florence, is presented. Non-invasive measurements of image spectroscopy (IS) have been employed to support the work of art-historians in the critical re-examination and interpretation of the graphical work of the artist. The multispectral analysis has been carried out over the extended spectral region (400–1700 nm), in order to provide simultaneous indications both on the pictorial materials and on possibly underlying hatches. The data processing has been performed by means of Principal Component Analysis (PCA) and the elaboration of each case has been addressed to specifically respond to questions related to the art-historical problem.     

The analysis of polychrome works of art: 40 years of infrared spectroscopic investigations

In this paper a synthetic chronological survey of analytical applications of infrared spectroscopy for the characterization of the materials of polychrome works of art and archaeology is outlined. Various sampling methods are described and some relevant examples, drawn from the published cases, are presented. The various methods prove to be very effective in characterizing both the inorganic and organic constituents of a wide variety of artworks, giving an insight into the materials and techniques of execution of the artifacts and, in the case of infrared mapping techniques, pinpointing the analytical data within a precise layer of the stratigraphy of the cross-sectioned samples. Overall, the great analytical potential and wide field of application of this technique is fully brought to light.     

Raman mapping analysis of pigments from Proas Iluminadas by Quinquela Martín

The painting Proas Iluminadas (Illuminated Bows) by Benito Quinquela Martín is studied by Raman spectroscopy in order to analyse the technique and the pigments employed by the artist: ultramarine blue, carbon black, cadmium-sulphure based compounds for the hue of yellow, orange and red; also zinc white, barium yellow, massicot yellow and viridian were observed. The importance of using different excitation laser lines in the analysis of mixtures of pigments is highlighted. The Raman mapping analysis of cross section samples shows the way the artist composed the ground layer: a lead white stratum over a calcite one. It also allows distinguishing between a mixture of components and strata superposition, both presenting the same appearance under an optical microscope. This paper provides information about the materials and techniques used in a period of Argentine art not studied before from this point of view.     

mtDNA analysis of the human remains buried in the sarcophagus of Federico II

The sarcophagus containing the remains of Federico II, located in the Cathedral of Palermo (Sicily, Italy), was opened on 1998 to perform a multidisciplinary survey [1]. Next to the remains of Federico II and in close contact with them were laying two other skeletons belonging, according to historical records, to Pietro II di Aragona and to an anonymous person (“The Third Individual”), probably a woman. The bones appeared severely deteriorated. Chemical analysis performed on bone samples excluded that the bodies underwent some kind of embalming process. The analysis of mtDNA from bone samples taken from the three skeletons was successful in only one of the two labs involved. The HVR1-mtDNA sequence (region: from nt 16,035 to nt 16,395), obtained from the bone samples of Federico II and “The Third Individual” appear identical but bear double peaks at the same nucleotide positions, suggesting mixing (i.e. contamination) of different mtDNA types. The HVR1 sequence obtained from the bone sample of Pietro II di Aragona does not present double peaks and differ from the Cambridge Reference Sequence (CRS) at six nucleotide positions. Cloning experiment of the Federico II amplicon demonstrated that the mixed mtDNA types are only two: one identical to CRS, the other identical to the sequence of Pietro II di Aragona. A reconstruction of these data are proposed in the Discussion. Due to the problematic context in which this study was carried out (mixed and deteriorated biological material, failure to replicate results in two different labs), our results and reconstruction can only be offered on a tentative basis. It is hoped that the data presented in this study will reveal useful, for future comparison, if further molecular genetics research will be carried out on the royal dynasties that ruled Sicily in the early centuries of the past millennium.     

Mosaic floors of roman Villa del Casale: Principal component analysis on spectrophotometric and colorimetric data

Spectrophotometric and colorimetric data obtained during a measurement campaign aimed at supporting the Roman “Villa del Casale” (Piazza Armerina, Sicily, Italy) conservation activities, are presented. Special attention was paid to the possible variation of the chromatic coordinates, possibly due to the interventions of cleaning, consolidation, and protection. Data have been analyzed by the Principal Component Analysis (PCA) statistical technique, with the attempt to investigate its role in data variability reduction and verify its effectiveness in interpreting the phenomena occurring on the mosaic surface of the Villa, through grouping the observations into homogenous clusters. Effectiveness in the use of the information provided by the spectrophotometric and colorimetric analyses is strongly related to the immediacy and ease of data reading by the restoration operators for whom the issues concerning the color measurement and its representation are often unfamiliar. This paper analyses data of different mosaic tesserae before/after the cleaning intervention and presents data clustering with PCA. This statistical technique has provided a synoptic scheme capable of improving data interpretation concerning the chromatic behavior of the materials. Moreover, the cluster distribution highlighted by the multivariate analysis made it possible to identify, more clearly, the parameters that mostly contribute to the chromatic shift and to monitor the behavior of variously colored tesserae.     

Surface analysis of stone materials integrating spatial data and computer vision techniques

This paper deals with a possible application of computer vision techniques in the field of Cultural Heritage. These techniques allow an effective integration of data from different sources. Particular consideration will be given to an accurate geometric analysis of the zone under study in order to detect degradation damage in historical building-stone materials. To this end, we employ a computer vision technique, known as the Shape from Shading method, for which a photographic image of the stone material under consideration is the only input data required. By using this method, it is possible to recover, under some constraints, the shape of the three-dimensional surface of the object from the photographic image. In order to improve the results, in this paper, we implement this technique by using an optimization approach which allows a suitable integration of photographic and spatial data, the latter of which is obtained by a topographical device. We outline the potentialities of the method which mainly consist of two relevant capabilities. The first one is the geometric shape reconstruction of the surface material at a resolution much higher than the one allowed by topographical acquisition. The second one is the correction of the lighting-induced distortions in the photographic image. Such a correction is relevant for further image-based analysis of the degradation of the stone material. Experimental results, obtained by using both photographic and spatial data relative to a pudding stone with degradation, are presented and discussed.     

Validating chemical and structural changes in painting materials by principal component analysis of spectroscopic data using internal mineral standards

This work shows the capability of principal component analysis (PCA) to detect molecular, chemical and mineralogical changes in historic painting materials subjected to a thermal ageing test (< 250 °C). To simulate the heat-induced alterations an ageing accelerated process was performed on two sets of samples containing two mineral phases (hydroxyapatite and quartz) and two organic compounds (collagen and albumin). The chosen minerals behaved as internal standards during the tests since they are stable and chemically inert at the tested temperatures. Raman microscopy (RM) was applied to characterise one set of samples made of bone, containing ca. 70% hydroxyapatite and 30% collagen. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy was used to study the other set of samples made of four different quartz/albumin mixtures with quartz contents of 30%, 50%, 70% and 90% (w/w). The aim was to identify the ideal proportion of internal standard to be validated by ATR-FTIR and PCA, determined to be 70%. PCA analyses detected changes in the molecular structures of the organic components while the internal mineral standard remained stable. Moreover, the internal standard IR/Raman bands were constant during the tests and confirmed that the results of PCA analyses were independent of instrumental and technical factors, as well as sample collecting and handling. This demonstrates the potential benefits of our approach to study historical painting materials, which have suffered any type of heat-induced alteration.     

Historical and probabilistic structural analysis of the Royal ditch aqueduct in the Alhambra (Granada)

The structural and historical analysis of the aqueduct of the Alhambra is presented. In the 13th century, Muhammad I built the palatial city of the Alhambra. To provide a water supply, Muhammad I built an irrigation ditch, known as the Royal ditch. The aqueduct was reconstructed in the 18th century in ashlar masonry to replace the original one. This work analyzes the history, geometric modeling, materials and stability of the aqueduct. Due to difficulties in testing and measuring the properties and loads, the Monte Carlo analysis technique is used to analyze stability, where the input parameters are defined as probabilistic distributions. Monte Carlo analysis provides the probability of risk of collapse defined by the geometric security coefficient obtained by means of the theory of limit analysis. Additionally, this technique is used to optimize the thickness of the arch.     

The varnished truth: The recipes and reality of tintype coatings

The most popular photographic technique in the USA between 1856 and 1900 was the tintype, with millions of these objects created by photographers in established studios, by itinerant artists in portable workshops, and by amateurs working from ‘how-to’ manuals and journal articles. Whereas the fundamentals for this photographic process (collodion binder on a japanned metal support) were largely invariant, historical documents recommended a wide variety of protective varnish materials. A collection of 221 tintypes was analyzed using pyrolysis gas chromatography-mass spectrometry (py-GC-MS) to compare the components of actual tintype varnishes with recipes from the historical literature. Several resins in published tintype varnish recipes, including mastic, copal, and amber, are entirely absent from this collection and only five constituents – shellac, Pinaceae resin (Canada balsam or colophony), dammar, sandarac, and camphor – are detected alone or in combination. Each detected resin appears in historical recipes, but just 24% of the samples have varnish layer constituents consistent with published tintype varnish recipes. Forty-four percent of the tintypes have varnish constituents consistent with formulations recommended for other collodion images, but the varnishes of the remaining samples have no direct literature equivalents. The preponderance of shellac- and Pinaceae-based varnishes suggests that these correspond to inexpensive commercial varnishes, but tintypists may have developed their own preferred mixtures or simply used what was at hand. This first in-depth technical analysis of tintype materials suggests that the cheapest and most readily available materials were employed in the varnishing process and that the artists were not bound by literature recommendations.     

Characterisation of wall paintings in the Sos Furrighesos necropolis (Anela,Italy)

The Sos Furrighesos necropolis (Anela) is considered to be one of the most important funerary monuments in Sardinia. The hypogeum consists of various graves, called Domus de Janas, which are decorated with Neolithic mural paintings and sculptures. This work was undertaken in order to clarify which techniques were used in the past, through the identification of pigments and binding media. The samples, scraped off from the paint surface, were studied by using various analytical techniques in order to characterise both the pigments and the binding media. The main problems concerning the characterisation were due to the small sizes (1–5 mg) of the samples and their complex nature. As regards pigments, X-ray diffraction and scanning electron microscopy-energy dispersive X-ray spectrometry analyses were performed on the samples. These techniques are well suited to the characterisation of inorganic pigments and have led to the identification of the red pigment as haematite. In order to characterise the organic binders, the samples were analysed by a procedure based on a gas chromatography–mass spectrometry technique, which allows proteinaceous and lipidic media determination in the same sample. In most of the samples, the presence of egg was suggested.