Scientific study of the pigments and binders used in mural painting from the 16th-century ce St Mary's Church of Cheriapally,Kottyam, Kerala,and its relevance to conservation

The aim of this investigation was to analyze the materials and techniques of the paintings in the 16th-century ce St Mary's Church, to evaluate deterioration of the paintings, and to propose a suitable conservation treatment for their preservation. The material analysis of ground, pigments, binders, and plasters was undertaken using binocular microscopy, field emission scanning electron microscopy (SEM)–energy dispersive X-ray spectroscopy, X-ray fluorescence, Fourier transform infrared spectroscopy in reflectance (KBr) and transmittance mode (attenuated total reflection), thin-film X-ray diffraction, and micro-Raman spectroscopy. Gas chromatography–mass spectrometry (GC-MS) was used for identifying proteinaceous and lipidic materials extracted from the micro-samples. The study generated data on two different red and green pigments used as decorative materials. The red pigments were identified as cinnabar along with traces of hematite and clay minerals, and green as malachite and the minor presence of other minerals. SEM analysis identified cotton fiber embedded in the coarse plaster layer that provided better strength to the plaster. Plant oils and proteins found as the binder in the pigment samples suggested that the painting technique was executed as tempera. Lead white and gypsum materials were used in previous restoration works.     

陕西旬邑西头遗址出土彩绘白灰面的成分和工艺分析

对陕西旬邑县西头遗址出土的彩绘白灰面进行了成分和制作工艺分析。采用偏光显微分析、扫描电镜能谱、X射线衍射,拉曼光谱分析了该彩绘面的颜料和石灰层成分,采用气相色谱-质谱联用技术(GC-MS)分析了该彩绘面的胶料成分。结果表明,该彩绘面的颜料由铁红,铁黄和绿土构成。白灰层由碳酸钙构成,部分样品中存在双层白灰层。GC-MS分析表明,该彩绘面的胶料含动物胶,可能还含蛋类。通过比较研究发现,旬邑彩绘白灰面的制作工艺和与后期壁画制作工艺相似,对其组成和工艺的研究将有助于探索先周时期关中地区壁画的起源和发展。     

Multi‐analytical Studies of Archaeological Chinese Earthen Plasters: The Inner Wall of the Longhu Hall (Yuzhen Palace,Ancient Building Complex,Wudang Mountains,China)

The Yuzhen Palace is one of the nine palaces in the Ancient Building Complex built by order of the Yongle Emperor during the Ming dynasty. The buildings were built with dressed black bricks. As a result of the planned national South–North Water Diversion project, the water level in the Danjiangkou Reservoir that surrounds the Yuzhen Palace was expected to rise by approximately 15 m. To avoid submersion of the site, three gates were elevated by 15 m in 2013 and other buildings dismantled, for later reconstruction. The characterization of the construction materials has therefore become of primary importance. Here, we present results on the plasters of the Longhu Hall. The analysis of materials involved a multi‐analytical approach combining optical and electron microscopy with X‐ray and vibrational spectromicroscopies and thermogravimetry. The results indicated the use of two earthen plaster layers and a whitewash finish coating applied over a thin preparatory intermediate layer to improve the adherence of the finish coating to the earthen plaster. Ramie and straw fibres identified in the earthen plasters were added to reduce shrinkage and cracking during drying. The raw materials used and the application technique pointed to a well‐established construction industry using traditional earthen building materials together with lime technology.     

CHARACTERIZATION OF PLASTERS FROM PTOLEMAIC BATHS: NEW EXCAVATIONS NEAR THE KARNAK TEMPLE COMPLEX,UPPER EGYPT*

The aim of the present work is to characterize plasters from Ptolemaic baths recently discovered in front of the Karnak temple complex, by the excavations of an Egyptian–French team. The characterization was carried out by means of optical microscopy (OM), scanning electron microscopy (SEM) equipped with an energy‐dispersive X‐ray detector (EDS), X‐ray diffraction analysis (XRD) and Fourier transform infrared spectroscopy (FT–IR). The results allowed the identification of the chemical composition and structure of these plasters. In addition, samples of red, yellow, black and white pigments were examined and identified. The results helped in providing an image concerning some materials used during the Ptolemaic era in ancient Egypt.     

Initial evidence of plant and animal-origin organic additives from the second-century bce earthen plaster of rock-cut caves of Karla,India*

Analytical investigations through phytochemical screening, scanning electron microscope (SEM) and light microscopic observation of the earthen plaster of Karla Caves of western India identified the presence of antifungal, antibacterial and insect repellent Careya arborea stem fibres as a vegetal additive. The scanning electron microscopy with energy-dispersive X-ray spectrometry (SEM-EDX) study also revealed the inclusion of rice (Oryza sativa) husk as a plant additive in the plaster. In the high rain-fed coastal regions of western India, the antimicrobial, antioxidant and termite-resistance properties of C. arborea helped the survival of the plaster in unfavourable climatic conditions. Besides, the C. arborea and rice husk together played a role in reducing cracks, decreasing the density, and imparting a plasticity and a durability to the plaster. The liquid Fourier-transform infrared spectrometer (FTIR) of organic extracts revealed carboxylic acid (fatty acids)-based additives in the earthen plaster. From the gas chromatography-mass spectrometry (GC-MS) analysis of the plaster, the presence of animal milk fat, animal and vegetable fat, and vegetable oil was identified, and probably used to strengthen the earthen plaster for their resistance to tensile stress. The analysis also diagnoses the inclusion of methyl commate B, a resinous material obtained from the Burseraceae plant family, which has antimicrobial properties, through GC-MS analysis.     

ANALYTICAL CHARACTERIZATION OF ROMAN PLASTERS OF THE ‘DOMUS FARINI’ IN MODENA*

The paper refers to the analytical characterization of Roman painted plasters dating back to the second century ad . The following techniques were used: optical microscopy (OM), scanning electron microscopy (SEM–EDS), micro‐Raman and Fourier transform infrared spectroscopies (µ‐Raman and FT–IR), X‐ray diffraction (XRPD), colorimetry and thermal analyses (TG/DTA). The investigation analysed the chemical composition and structure of the plasters, the chemical composition of the pigment layers, the use of binders and any chemical alteration of pigments as well as deterioration of the samples. Stratigraphic analysis of plasters allowed identification of their individual components, which proved helpful in finding out more about the mural painting technique employed.     

Differentiating between anthropogenic calcite in plaster,ash and natural calcite using infrared spectroscopy: implications in archaeology

Infrared spectroscopy provides information not only on the type of calcium carbonate polymorph, but also on the extent of atomic order. In calcite, three major infrared absorption peaks are identified: ν₃, ν₂, and ν₄. It was shown that the ratio between ν₂ and ν₄ bands reflects the order of the calcite crystal structure. In this paper we analyse this ratio in geologically formed calcites, archaeological plasters, modern plasters and experimentally prepared plasters. For the geological calcite, the values of the ν₂/ν₄ ratio are around 3, whereas for the experimentally prepared plasters, the values are around 6.5. The ν₂/ν₄ ratio for archaeological plasters varies from 3 to 6. This shows that a high ratio is indicative of disorder in the crystal, and implies that the calcite was formed from calcium oxide at high temperatures. It also implies that this disorder can be preserved for at least 14,000 years. The ν₂/ν₄ ratio of calcite from archaeological sites can thus be used to differentiate between anthropogenic calcite, such as in plaster, mortar and wood ash, from geogenic calcite, such as in limestone. The ratio may also be used to identify plaster or ash that still retains its original crystals and therefore carbon-14 content.     

CHARACTERIZATION AND PROVENANCE OF LIME PLASTERS FROM THE TEMPLO MAYOR OF TENOCHTITLAN (MEXICO CITY)

In this work, we present the results of the analyses of 20 lime plaster samples taken from the Templo Mayor (Great Temple), the main pyramid of Tenochtitlan (Mexico), the ancient capital of the Mexicas. The samples were analysed to recover information on the mixtures used in the fabrication of the plasters and for the provenance of the raw materials (in particular, limestone) used to make the plasters. The characterization of the samples was done by OM, SEM/EDS, XRF and LA–ICP–MS analyses, while the identification of the provenance of raw materials was done by studying the lumps present in the samples with LA–ICP–MS. The objective of the study was to establish if there was a relationship between changes in the construction techniques employed in the pyramid over time and if there were changes in the provenance of the raw materials. Six different construction phases of this pyramid are analysed, showing the similarities and differences among them, mainly based on differences in the sieving of the aggregates and in the raw materials employed. The provenance studies of the limestone used to make the plasters demonstrated that all the limestone comes from the Tula region.     

Characterization of lime carbonates in plasters from Teotihuacan,Mexico: preliminary results of cathodoluminescence and carbon isotope analyses

This study characterizes the degree of calcination of lime in lime plaster samples from Teotihuacan, the capital of a regional state in prehispanic Central Mexico. Lime plaster production consists of multiple steps, from the firing of raw materials to the mixing of lime and aggregate and the final application. While previous studies have focused on the compositional variability, specifically the recipe of lime plasters and mortars, the characterization of lime itself has not been sufficiently addressed. In this study, cathodoluminescence analysis coupled with petrographic and image analyses were employed to examine the degree of calcination of lime. The results of cathodoluminescence petrography were further examined through stable carbon isotope and ¹⁴C measurements. It appeared that the results of cathodoluminescence analysis are consistent with those of other analytical methods and that there are diachronic changes in the degree of calcination of lime among lime plaster samples. This implies changes in the organization of lime production, specifically the consistency in the control of firing temperature.     

Characterization of Late Prehistoric Plasters and Mortars from Erimi – Laonin tou Porakou (Limassol,Cyprus)

Several plasters and mortars from the Middle Bronze Age site of Erimi – Laonin tou Porakou (Cyprus) were analysed in order to perform a technological characterization. Morphological (SEM), elemental (EDX), mineralogical (XRPD), petrographic (polarized OM, SEM–EDX), thermal (TGA) and spectroscopic (FT–IR) techniques were applied. Plasters and mortars were identified as pyrotechnological lime products, obtained using local raw materials and containing a moderate amount of spathic calcite fragments. The use of organic fibres was ascertained and a seminal use of a crumbled ceramic as additive was evidenced.     

湖南桃源出土战国彩绘陶器的科学分析

为研究湖南桃源县战国楚墓出土彩绘陶器的组成结构及保存现状,采用能量色散X射线荧光光谱法(EDXRF)、扫描电镜-能谱法(SEM-EDS)、X射线衍射法(XRD)和激光拉曼光谱法(LRS)等手段对陶器胎体成分、表面彩绘、金属涂层等进行分析检测。结果表明:这批彩绘陶器胎体成分相近,为普通易熔黏土。彩绘陶器表面的红色颜料为朱砂(HgS),黑色颜料为炭黑(C)。在彩绘陶壶、陶鼎和陶敦表面发现金属涂层装饰,通过扫描电镜能谱和X射线衍射分析,确定涂层为单质锡,属于锡涂陶的范畴。同时红外光谱测试显示锡层内面棕黑色物质为生漆,可能混合其他胶结材料。以上结果为研究战国时期彩绘陶器,特别是锡涂陶的制作工艺及发展提供了新的资料。     

The Beginnings of Pyrotechnology: Neolithic and Egyptian Lime Plaster

Abstract

Characterization of pre-pottery Neolithic and Egyptian plasters has been carried out, with emphasis on microstructural observations with the scanning electron microscope. Samples from Asikli Hüyük, Çayönü Tepesi, Tell Ramad, and Jericho were examined; the results show that true lime plasters were utilized in the aceramic Neolithic. The quantity of material used and the temperature necessary for limestone calcination imply that some sort of crude kilns must have been employed. The availability of this technology makes understandable the subsequent rapid development of fired pottery. Samples of Egyptian plaster from Timna (ca. 1400–1200 B.C.) were found to be lime, contradicting Lucas' statement that lime plasters were unknown in Egypt prior to the Ptolemaic period. Gypsum plasters of both Neolithic and Egyptian origin have also been characterized.     

WHITE LUMPS IN FIFTH- TO SEVENTEENTH-CENTURY AD MORTARS FROM NORTHERN ITALY

Ancient mortars from northern Italy, dating from the fifth to the seventeenth century AD, were examined in order to formulate an hypothesis regarding the origin of the white lumps often observed in these mortars and in other samples of the same geographical provenance. Various characterization techniques were employed, including scanning electron microscopy, X-ray powder diffraction and Fourier transform infrared (FTIR) and micro-FTIR spectroscopy.     

Plasters from Different Buildings of the Sacred Precinct of Tenochtitlan (Mexico City): Characterization And Provenance

In this work, we present the results of the characterization of 20 lime plaster samples taken from the Sacred Precinct of Tenochtitlan (Mexico City), the ancient capital of the Aztec empire. The samples come from different buildings of this precinct (A, B and D) and from the west façade of phase VI of the Templo Mayor pyramid. The objective of the work is to characterize the plaster samples, to understand the raw materials used, and to evaluate the presence of similarities and differences among the samples in the building techniques and raw materials employed. All the samples were studied with OM, SEM–EDS and LA–ICP–MS. The study provided evidence of the plastering and replastering practice in the same constructive phases. The results of the analyses showed the existence of important similarities and differences among buildings and constructive phases in the Sacred Precinct. In order to understand the provenance of the limestone used in the plasters, the lumps and the binder of the samples were analysed. The results were compared with those of the limestone outcrops located in central Mexico. The provenance study showed that all the limestone used in the construction of the analysed buildings of Tenochtitlan's Sacred Precinct comes from the Tula region.     

The painting of the Etruscan “Tomba della Quadriga Infernale” (4th century BC), in Sarteano (Siena, Italy): technical features

This work presents the results of an investigation of the painting technique used in the Etruscan tomb “Tomba della Quadriga Infernale”. This tomb was discovered in Sarteano (Siena, Italy) in October 2003 and dated back to the second half of the 4th century BC. Red, dark red, pink, yellow, white, black, and grey colours were used in the tomb in order to create paintings, which now represent a very precious record of the Etruscan art of wall painting in a hypogeal environment. The technical features of the painting were revealed by stratigraphy using optical and electronic microscopy. The components and preparatory layers of the painted areas were characterized using Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray microanalysis (SEM-EDS), X-ray diffraction (XRD), and gas chromatography/mass spectrometry (GC/MS). XRD, SEM-EDS, and optical microscopic techniques were also used for mineralogical analysis of the rock substrate. The SEM-EDS and FTIR analyses showed that red and yellow ochre, calcite, and vegetable charcoal were used to paint the walls of the tomb: the pigments, either alone or mixed together, were utilized to produce pure colours (red, yellow, white, and black) and intermediate tonalities (pink, dark red, and grey). SEM-EDS, FTIR, and XRD highlighted that the painting was made on a preparatory layer of calcite, applied onto a levelling material made up of calcite, clay minerals, quartz, and iron oxides. GC/MS analyses revealed that egg was used as an organic binder to disperse the pigments.     

Multimethod characterization of terracotta figurines and lime mortar from the elite burials Shoroon Bumbagar I and II,Mongolia

The multi-analytical approach, including X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy with X-ray (SEM-EDX), was applied to terracotta figurines, mural plaster, and local clay sources coming from two elite burials in Mongolia—Shoroon Bumbagar I and Shoroon Bumbagar II—dated to the second half of the VII century AD. The aims of this study were: (1) by comparing the major composition of body samples with those of the ancient Tang sancai kilns to identify the origin of raw materials; and (2) to track changes in the manufacturing technology. Analysis of CaO, Fe₂O₃, TiO_2, and K₂O, which were crucial for distinguishing the provenance of red bodies, confirmed the local production of terracotta figurines. Furthermore, this study helped us attain a deeper understanding of the Tang sancai at both Shoroon Bumbagar sites, geographically located on both banks of the Tuul River yet separated in time by a few decades; it suggests the movement of two groups of artisans using different technologies to make Tang sancai locally by incorporating local tastes and traditions.     

New evidence of adhesive as hafting material on Middle and Upper Palaeolithic artefacts from Gura Cheii-Râşnov Cave (Romania)

Making use of analytical, chemical and mineralogical methods, this paper focuses on the analysis of inclusions in order to address the question of the provenance of prehistoric artefacts excavated in Gura Cheii-Râ?nov Cave (Romania). The study represents the first discovery of bitumen on lithic tools belonging to the Upper and Middle Palaeolithic in Europe. The material was identified through several analytical procedures, such as Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray fluorescence (EDXRF), inductively coupled plasma atomic emission spectroscopy (ICP-AES), and X-ray diffraction (XRD).     

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.