Analytical characterization of paintings on pre-Roman pottery by means of spectroscopic techniques. Part II: Red, brown and black colored shards

As a part of a systematic study aimed at assessing the chemical composition of ancient pigments as well as at collecting information useful for the understanding of the technical aspects related to pottery preservation and decoration, the results of analysis performed on red, brown and black pigments decorating pre-Roman pottery excavated in thirteen different tombs unearthed in the archaeological zone of Canosa (Puglia, Italy) are presented. Both surface (XPS) and bulk (FT-IR) spectroscopies were used which gave complementary information and XRD was used in some cases to further support the spectral assignments. Results suggested that the shards characterized by “nominally” the same color could be differentiated by the chemical composition of the pigmented layers; in particular, the shards exhibiting the red pigment could be divided into three groups containing, respectively, either hematite or ochre plus other substances not related to the color but of great concern for the understanding of ancient techniques used for color preparation. Manganese oxides were found to be the basis of the brown pigments, which could be divided into three groups on the basis of Mn and Fe contents. Either magnetite or carbon of vegetable origin was found in the black-pigmented layers. Furthermore, an attempt was made to find a possible correlation between this classification and the results of a provenance study carried out on the same pool of shards analyzed in the present investigation. Received: 28 May 1999 / Revised: 6 August 1999 / Accepted: 21 August 1999     

The identification by Raman microscopy and X-ray diffraction of iron-oxide pigments and of the red pigments found on Italian pottery fragments

The technique of Raman microscopy has been used to identify and characterise the pigments used in red shards of medieval and earlier items of pottery which have been found in various archaeological sites in the South of Italy. The research has led to the identification, on the basis of their characteristic Raman/resonance Raman spectra, of the red pigments as iron(III) oxide (e.g. Indian Red, Red Ochre or Venetian Red) and the yellow pigments as hydrated iron(III) oxyhydroxide (e.g. Yellow Ochre and Mars Yellow). X-ray powder diffraction experiments confirm the conclusions drawn above.     

On-site analysis of archaeological artifacts excavated from the site on the outcrop at Northwest Saqqara,Egypt, by using a newly developed portable fluorescence spectrometer and diffractometer

Blue-painted pottery was produced in the New Kingdom, Egypt, and decorated with blue, red, and black pigment. In this study, two newly developed portable instruments, a portable X-ray fluorescence spectrometer and a portable X-ray powder diffractometer, were brought to the site on the outcrop at Northwest Saqqara, an archaeological site in Egypt, to verify their performance in on-site analysis of excavated artifacts at the site. Pigments used for the blue-painted pottery and plasters in the New Kingdom were analyzed by these instruments on the basis of both their chemical compositions and crystal-structural information. The blue pigments were identified as two different pigments, Egyptian blue and cobalt blue. The diffraction pattern of the blue pigment of the painted pottery exhibited that of spinel structure. The XRF spectrum of the blue pigment obtained by the same instrument from the same position indicates the presence of Mn, Co, Fe, Ni, and Zn. The possibility of compositional transitions of the cobalt blue pigment with time was revealed on by detailed analysis of the XRF data. The reason for the transitions is considered together with the archaeological background of the New Kingdom, Egypt.     

Laser-induced breakdown spectroscopy for semi-quantitative and quantitative analyses of artworks—application on multi-layered ceramics and copper based alloys

In the present work, we report on the analyses of different types of artworks, such as medieval glazed Umbrian pottery and copper based alloys from Roman and modern periods, performed by means of Laser Induced Breakdown Spectroscopy (LIBS). The semi-quantitative analyses on the multi-layered ceramic findings regard glaze, luster and pigment decorations present on the surface. The composition for each decorative layer was determined by estimating the contribution of the ceramic layer beneath the examined one to the whole plasma emission. Two types of ancient luster have been considered: red and gold, while the pigments examined include painted decorations of different blue tonalities. The measured elemental composition of the decorative layers resulted partially correlated with the color of the painted surface, measured by a standard UV-VIS spectrometer. In LIBS analyses of bronze samples, a procedure was developed, which improves data repeatability and extends quantitative measurements to minor elemental constituents. Results of the quantitative analyses gave indications about the manufacturing process of the artwork, its actual degree of conservation and the presence of residual surface decorations.     

Raman spectroscopic study of ancient South African domestic clay pottery

The technique of Raman spectroscopy was used to examine the composition of ancient African domestic clay pottery of South African origin. One sample from each of four archaeological sites including Rooiwal, Lydenburg, Makahane and Graskop was studied. Normal dispersive Raman spectroscopy was found to be the most effective analytical technique in this study. XRF, XRD and FT-IR spectroscopy were used as complementary techniques. All representative samples contained common features, which were characterised by kaolin (Al2Si2O5(OH)5), illite (KAl4(Si7AlO20)(OH)4), feldspar (K- and NaAlSi3O8), quartz (alpha-SiO2), hematite (alpha-Fe2O3), montmorillonite (Mg3(Si,Al)4(OH)2 x 4.5 5H(2)O[Mg]0.35), and calcium silicate (CaSiO3). Gypsum (CaSO4 x 2H2O) and calcium carbonates (most likely calcite, CaCO3) were detected by Raman spectroscopy in Lydenburg, Makahane and Graskop shards. Amorphous carbon (with accompanying phosphates) was observed in the Raman spectra of Lydenburg, Rooiwal and Makahane shards, while rutile (TiO(2)) appeared only in Makahane shard. The Raman spectra of Lydenburg and Rooiwal shards further showed the presence of anhydrite (CaSO4). The results showed that South African potters used a mixture of clays as raw materials. The firing temperature for most samples did not exceed 800 degrees C, which suggests the use of open fire. The reddish brown and grayish black colours were likely due to hematite and amorphous carbon, respectively.     

Neutron activation analysis of bulk samples from Chinese ancient porcelain to provenance research

Neutron activation analysis (NAA) is an important technique to determine the provenance of ancient ceramics. The most common technique used for preparing ancient samples for NAA is to grind them into a powder and then encapsulate them before neutron irradiation. Unfortunately, ceramic materials are typically very hard making it a challenge to grind them into a powder. In this study we utilize bulk porcelain samples cut from ancient shards. The bulk samples are irradiated by neutrons alongside samples that have been conventionally ground into a powder. The NAA for both the bulk samples and powders are compared and shown to provide equivalent information regarding their chemical composition. Also, the multivariate statistical have been employed to the analysis data for check the consistency. The findings suggest that NAA results are less dependent on the state of the porcelain sample, and thus bulk samples cut from shards may be used to effectively determine their provenance.     

The compositional and mineralogical analysis of fired pigments in Nasca pottery from Cahuachi (Peru) by the combined use of the portable PIXE-alpha and portable XRD techniques

An analytical protocol based on the combined use of the portable PIXE-alpha (Particle Induced X-ray Emission) and XRD (X-ray Diffraction) non destructive techniques developed at the LANDIS laboratory (Laboratorio di Analisi Non Distruttive) of the INFN–CNR (Istituto Nazionale di Fisica Nucleare–Consiglio Nazionale delle Ricerche) in Catania (Italy), was applied for the characterisation of the surface paints of some archaeological fragments of Nasca pottery from the Ceremonial Centre of Cahuachi in Southern Peru.Measurements were carried out on the black, white, red, orange and grey pigments; quantitative information on the chemical composition as well as on the mineralogical phases present on the paints were obtained.Results allowed to make some considerations about the materials and the manufacturing technique used to realise such fired pigments.It should be noted that during firing the precursor minerals composing the pigments undergo a phase transformation and their identification presents some difficulties.     

Raman microspectroscopy and SEM/EDS in the investigation of white and red painting layers from Celtic pottery from a Modlniczka site in Poland

Red and white painting layers from Celtic pottery from Southern Poland (Modlniczka 2 site near Kraków) were investigated with the use of Raman microspectroscopy, SEM/EDS and optical microscopy. The painting layers were performed homogeneously for all the examined shards, i.e. red layers as thinner, ca. 0,02 mm and white of 0,04 mm. The white painting layers are very fine grained and amorphous under SEM, prepared of compositionally complex magnesium based raw material, with phosphates and fluorite probably used as fluxes. Unusual phases: fluorite and silicon were identified. Raman spectroscopy of fine grained red painting layers revealed the presence of hematite and anatase/leucoxen. Again, rare phases, of silicon and destinezite were found. Both paints were carefully manufactured by grinding and homogenizing the raw materials. Their preliminary firing cannot be excluded. The painted pottery was fired approx. at 700–900 °C, but multistage firing is possible.     

唐代彩绘陶俑中无机颜料的化学组成

采用X射线粉末衍射（XRD）、X射线荧光光谱（XRF）和扫描电子显微镜-能谱（SEM-EDS）等测试技术对西安西曹M16唐墓出土的2尊唐代彩绘陶俑颜料进行了化学组成分析。结果表明,陶俑中含有丰富的无机颜料,其中红色颜料的显色成分为铅丹（Pb₃O₄）;白色颜料的显色成分为铅白（PbCO₃）和石灰石（CaCO₃）;粉色颜料的主要显色成分为铅丹和铅白的混合物;青色颜料为铜绿（Cu₂（OH）₂CO₃）和青石（Cu₃（OH）₂（CO₃）₂）混合物。     

Chemical composition of contemporary black printing inks based on infrared spectroscopy: basic information for the characterization and discrimination of artistic prints

This article aims to provide the basic information necessary to afford the discrimination of artistic prints based on chemical information. The presence of original and non-original prints in the art market is a real problem, especially for contemporary artists. Most of the non-original elements can be distinguished on the basis of their stylistics and printing characteristics, but sometimes this information is not enough. To facilitate discrimination in these cases, we propose to add, to the previously indicated aspects, the chemical information of the materials involved in the production of the original series (inks, paper and pencil). Comparison of the composition of any element with that established for the original series will permit the attribution of any doubtful element. This article is focused on the evaluation of this approach by determining the chemical composition of contemporary black printing inks by infrared spectroscopy and by searching, on the basis of the information obtained, for criteria capable to discriminate between prints made of different inks. The success of the approach with this set of inks could easily be extended to the study of colour inks. The study also includes the characterization and discrimination of black pigments because they are the most characteristic component of these inks and because this information can also be useful for other artistic studies. The procedure proposed permits the analysis of inks with minimum deterioration of the artwork. Results indicate the capability of the approach because, following the procedure, it is possible to distinguish between black pigments attending to the presence of hydroxyapatite, silicate and some other specific bands, whereas black inks can be discriminated by paying attention to the inclusion in their composition of such pigments as bone black, Prussian blue, mars brown or other specific bands. Scanning electron microscopy analyses have corroborated the results obtained.     

Brown ceramic pigments based on open-hearth slag

The possibility and expediency of the application of dump waste open-hearth slag for obtaining ceramic pigments was revealed on the basis of complex physicochemical studies. Ceramic pigments of a brown color gamma were synthesized in the system open-hearth slag-Cr₂O₃-NiO. The composition of the crystal phase of roasting products of pigment burdens and its correlation with optical color indexes were determined. Laboratory and production tests of developed slag-containing pigments in the composition of various vitreous coatings were carried out.     

Analytical characterisation of pigments on pre-Roman pottery by means of spectroscopic techniques Part I: white coloured shards

This paper is part of a systematic archaeometric investigation aimed at the characterisation of the pigments and related materials (ligand, colour substrate) used in decoration of pottery excavated in the archaeological zone of Canosa (Puglia, Italy). Shards found in thirteen different tombs have been analysed; in this paper samples exhibiting a white colouration have been selected. Both surface (XPS) and bulk (FT-IR) spectroscopies were used which gave complementary information and enabled white pigments to be divided into two groups. Moreover, X-ray diffraction was used in some cases to further support some spectral assignments. The molecular specificity of FT-IR, when applied to the analysis of both pigments and ceramic body, allowed the identification of the various constituents and, hence, provided indirect information on the end-use of the original wares. The potential of the combined use of different spectroscopies to obtain valuable information on both painting materials and technical aspects is shown.     

Application of chemical and chemometric analytical techniques to the study of ancient ceramics from Dougga (Tunisia)

In the present paper chemical characterization has been carried out on 67 shards of archaeological pottery from Dougga (North Tunisia). The analysed shards, dated to the Byzantine period (VI–VII century A.D.), belong to the three ceramic classes African Red Slip Ware, Dougga Ware and African cooking Ware. Fourteen elements have been determined by both atomic emission spectroscopy with flame as source (AES) and by using an inductively coupled plasma source (ICP-OES). The data acquired have been treated by statistical techniques in order to define grouping for the examined shards. Both unsupervised and supervised methods have been employed in order to define groups of different pottery shards. As a comparison, some samples (control group) coming from Southern Tunisia have been examined. All the statistical methods employed have evidenced how the control group, as concerns the chemical composition, is clearly distinguishable from Ain Wassel samples which are highly homogeneous. In fact because of the compositional homogeneity of the Northern Tunisia productions, it is quite difficult to establish a good classification and distribution of the samples in well defined cluster. Nevertheless supervised analysis has evidenced how, among the three classes, the African cooking Ware is the more distinguishable one confirming the archaeologists' hypothesis that Dougga Ware is an imitation of African Red Slip Ware.     

Use of various spectroscopy techniques to investigate raw materials and define processes in the overpainting of Apulian red figured pottery (4th century BC) from southern Italy

Analytical investigations using Scanning Electron Microscopy (SEM), with Energy Dispersive Spectrometry (EDS), X-ray Diffraction (XRD), Infrared Spectroscopy (FT-IR) and High Resolution Magic Angle Spinning Nuclear Magnetic Resonance (CP-MAS NMR), were carried out on white, yellow and red overpaintings on Apulian red-figured pottery fragments (4th century BC) from Altamura, Monte Sannace and Canosa - among the most relevant archaeological sites in ancient Peucetia - in order to outline technological features and define the nature of pigments. The results obtained allow us to highlight that Apulian objects have an external appearance which is very similar to Attic objects, but that they are nevertheless different, as they were made using locally available raw materials employing similar but not identical production technology. Perhaps familiarity, rather than real and proper continuity with the Attic pottery tradition, would explain the analytical results.Moreover, this paper proves that solid state nuclear magnetic spectroscopy (CP-MAS NMR) is a useful analytical tool for the examination of ancient pottery, which is also suitable for the identification of its firing temperature.     

Spectroscopic techniques applied to the characterization of recently excavated ancient potteries from Thiruverkadu Tamilnadu, India

The systematic and scientific study of artifacts reflects technological development and civilizations during the past. The importance of pottery artifacts as indicators of the artistic and technological advances reached by the ancient culture is investigatedby a number of techniques. Spectroscopic studies have been performed on recently excavated archaeological pottery samples from Thiruverkadu, Tamilnadu, India. The clay mineral type and its structural deformation due to firing have been studied from their Fourier transform infrared (FT-IR) spectra. The maximum firing temperature attained during baring, firing conditions (open/reduced atmosphere) and iron mineral phase changes is well established. X-ray diffraction (XRD) is used to identify minerals in the potsherds. Further scanning electron microscope (SEM) studies on potsherds pave the way to microstructural analysis and trace the subsequent development of virtification stages, thereby firing temperature is being confirmed. The results obtained from the different techniques provide the information for understanding the technological conditions implemented for the production of pottery and are found to give useful information about the analytical composition of potteries.     

Analytical characterisation of pigments on pre-Roman pottery by means of spectroscopic techniques Part I: white coloured shards

This paper is part of a systematic archaeometric investigation aimed at the characterisation of the pigments and related materials (ligand, colour substrate) used in decoration of pottery excavated in the archaeological zone of Canosa (Puglia, Italy). Shards found in thirteen different tombs have been analysed; in this paper samples exhibiting a white colouration have been selected. Both surface (XPS) and bulk (FT-IR) spectroscopies were used which gave complementary information and enabled white pigments to be divided into two groups. Moreover, X-ray diffraction was used in some cases to further support some spectral assignments. The molecular specificity of FT-IR, when applied to the analysis of both pigments and ceramic body, allowed the identification of the various constituents and, hence, provided indirect information on the end-use of the original wares. The potential of the combined use of different spectroscopies to obtain valuable information on both painting materials and technical aspects is shown. Received: 5 December 1997 / Revised: 16 March 1998 / Accepted: 19 March 1998     

Study of mural paintings using in situ XRF, confocal synchrotron-μ-XRF, μ-XRD, optical microscopy, and SEM-EDS--the case of the frescoes from Misericordia Church of Odemira

In this work, we present the results of an analytical method developed for detailed pigment identification, stratigraphy, and degradation of the paint layers of mural paintings applied in the study of the 17th century frescoes from the Misericordia Church of Odemira (Southwest Portugal). In situ X-ray fluorescence spectrometry analyses were performed on three panels of the mural paintings and complemented by colorimetric measurements. The different color areas were also sampled as microfragments (approx. 1 mm2) that were studied as taken or mounted in epoxy resin to expose the different paint layers. The microfragments of paint layers and their cross sections were characterized by optical microscopy and scanning electron microscopy coupled with energy dispersive X-ray spectrometry. Furthermore, elemental analysis was obtained with spatially resolved confocal synchrotron radiation μ-X-ray fluorescence spectrometry performed at ANKA synchrotron FLUO beamline. Occasionally, phase analysis by μ-X-ray diffraction was also performed. Results from the different techniques allowed pigment identification and, in some cases, the evaluation of color changes due to degradation processes and, considering the Southern Portugal geology, the identification of their possible provenance. The pigments used were essentially yellow, brown and red ochres, smalt blue, copper green, and black earths, probably from local sources.     

Analysis of the Chemical Composition of Red Pigments and Inks for the Characterization and Differentiation of Contemporary Prints

Prints are one of the most popular artistic forms. They consist of an original matrix that is printed on a paper support. The stamps are part of a series, and each series is composed of a particular number of prints. Many contemporary prints are made using oil inks and synthetic pigments (reds and yellows). Inks are mainly composed of pigments (organic or inorganic) and a binding medium. The analysis of inks has the potential to facilitate and complement the identification of stamps of different origins.

Fourier transform infrared spectroscopy (FTIR) and Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX) are techniques that are typically available in museums and centers related to the study of works of art. Both can be classified as micro-destructive and provide complementary information about the organic and some inorganic compounds (FTIR), and the elemental composition (SEM-EDX). In this article, the two techniques were used to analyze the composition of red ink in prints. As a result of these analyses, it was possible to distinguish among nearly all of the pigments and inks, indicating that the composition of the red ink can be reliably used to differentiate between stamps of different origins in a series of prints.     

Study of provenance character on ancient porcelain of Yue Kiln at Silongkou with NAA

Chemical composition is an important information of studying the provenance character of ancient pottery and porcelain. The ancient celadon samples produced in Later Tang (850–907 A.D.) to Former Southern Song (1127–1279 A.D.) have been analyzed with NAA. Its provenance characteristic was compared with that of Hongzhou Kiln of Jiangxi Province and Yaozhou Kiln of Shanxi Province in this paper. The experimental data were studied with statistic methods. The results indicated that the chemical compositions of ancient porcelain body samples made in three kilns were different. The difference is able to be identified. The porcelain body materials of both Silongkou Yue Kiln and Hongzhou Kiln were similar. The samples of Yaozhou kiln in north of China existed obvious difference.     

Multivariate chemical mapping of pigments and binders in easel painting cross-sections by micro IR reflection spectroscopy

Paintings are composed of superimposed layers of inorganic and organic materials (pigments and binders). Knowledge of the stratigraphic sequence of these heterogeneous layers is fundamental for understanding the artist’s painting technique and for conservation issues. In this study, micro-IR mapping experiments in reflection mode have been carried out on cross-sections taken from simulations of ancient easel paintings. The objective was to locate both organic binders and inorganic pigments. Chemical maps have been re-constructed using the common approach based on the integration of specific infrared bands. However, owing to the complexity of painting materials, this approach is not always applicable when dealing with broad and superimposed spectral features and with reststrahlen or derivative-like bands resulting from acquisition in reflection mode. To overcome these limitations, principal-component analysis has been successfully used for the re-construction of the image, extracting the relevant information from the complex full spectral data sets and obtaining reliable chemical distributions of the stratigraphy materials. Different pigment–binder combinations have been evaluated in order to understand limitations and strengths of the approach. Finally, the method has been applied for stratigraphic characterization of a cross-section from a 17th century wooden sculpture identifying both the original paint layer and the several overpaintings constituting the complex stratigraphy.