A multi-analytical investigation of the materials and painting technique of a wall painting from the church of Copacabana de Andamarca (Bolivia)

Cyclododecane shaping, sublimation rate and residue analysis for the extraction of painting micro-samples from resin cross-sections

Cross-section preparation of painting micro-samples is part of their routine analysis. This type of preparation can be used for several analytical techniques, such as scanning electron microscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, and optical microscopy. These techniques offer high-resolution imaging and/or elemental information, providing access to technical and material data important for the interpretation, preservation, and restoration of painted artworks. However, it also means that the material from the sample embedded in the resin becomes unreachable for further analysis, except for the polished surface of the cross-section. Degradation of the embedding medium can also occur over time, which can lead to misinterpretation, loss of information, or even complete destruction of the embedded sample. In the field of cultural heritage, cyclododecane (CDD) is commonly used for the consolidation and protection of objects, and is used in the preparation of cross-sections to prevent contamination of the sample by the embedding medium. This study enhanced the existing preparation process by shaping the CDD layer to enable extraction of the micro-sample from the resin if needed, without compromising the integrity of the sample. Moreover, the purity, the sublimation rate in a normal environment and a vacuum, and the impact of CDD on three different types of samples (historical painting on a canvas, wall painting fragment, model sample) were examined.

Conductive cross-section preparation of non-conductive painting micro-samples for SEM analysis

Scanning electron microscopy (SEM) is a common method for the analysis of painting micro-samples. The high resolution of this technique offers precise surface analysis and can be coupled with an energy-dispersive spectrometer for the acquisition of the elemental composition. For light microscopy and SEM analysis, the painting micro-samples are commonly prepared as cross-sections, where the micro-sample positioned on the side is embedded in a resin. Therefore, the sequence of its layers is exposed after the cross-section is polished. In common cases outside of cultural heritage, a conductive layer is applied on the polished side, but in this field, the measurements are mostly done in low-vacuum SEM (LV-SEM). Although the charging effect is reduced in LV-SEM, it can still occur, and can hardly be prevented even with carbon tape or paint. This work presents two conductive cross-section preparation methods for non-conductive samples, which reduce charging effects without impairing the sample integrity.

Multi-analytical approach to the mural painting from an ancient tomb of Ming Dynasty in Jiyuan, China: Characterization of materials and techniques

The pigments, surface deposition, preparatory layer and support from a mural painting tomb of Ming Dynasty (1368-1644 CE) were first time analyzed by micro-Raman, Fourier-transform Infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscope with energy-dispersive X-ray microanalysis (SEM-EDX), thermogravimetry and differential scanning calorimetry (TG-DSC) to reach a better understanding of the composition of the materials and the techniques adopted. All the pigments were identified, including hematite, cinnabar, malachite, yellow ochre, calcite and carbon black. The preparatory layer was found to be prepared by fine lime mortar with cotton fiber inside. The crystalline depositions on the mural painting were identified as calcite and dolomite originated from the lime-based preparatory layer. The support was found to be constructed with sticky rice lime mortar with several kinds of additives. The original lime stone was demonstrated to be magnesium-rich and the carbonization results were also discussed. These results revealed significant information on the materials and techniques used to build mural painting tomb in Ming Dynasty. This will benefit the further restoration and conservation works and also provide a methodology solution for the scientific analysis of ancient tomb mural paintings.

Investigation on the Painting Materials and Profile Structures Used in Ancient Chinese Folk Architectural Paintings by Multiple Analytical Methods

In order to understand the painting materials and profile structures used in the creation of Chinese ancient folk architectural paintings, the architectural paintings of the Bell and Drum Tower at Fushan Temple in Shaanxi Province of China was investigated. In this study, optical microscopy, Fourier transform infrared spectroscopy (FTIR), micro-Raman spectroscopy, scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS), and chemical experimental methods were used. The profile structures, and the elemental and chemical compositions of the pigments and binders in the ground layer of the 12 samples were determined. Results showed that the painting profile structures in both towers comprised of pigment layer, underpainting layer and ground layer, where no starch was found in the chalk ground layer. The pigment layer mainly comprised of iron oxide red, chalk, lapis lazuli, carbon black, green earth, and a dark green pigment that is formed by a combination of carbon black and green earth. To-date, the use of green earth pigment in Chinese architectural paintings was not found in Chinese related academic literature; hence, this study marked the first identification of green earth being used in the architectural paintings. Tung oil, commonly used in Chinese architectural paintings as a binder for pigment, was also identified in the samples. Results from this study will serve as an important reference for better scientific investigation methods on ancient Chinese folk painting materials.

Mass spectrometry in art conservation-With focus on paintings

Conservation of historic artifacts has been a multidisciplinary field from its very beginning. Traditionally, it has been and still is associated with the history of art. It applies knowledge from technical and basic sciences, adapting their solutions to its goals. At present, however, a new tendency is clearly emerging-scientific research is starting to play an increasingly important role not only as a service, but also by proposing new solutions both in the traditional conservation areas and in new areas of conservation activities. The above trend opens up new perspectives for the field of preservation of our heritage but may also create new threats. Therefore, the conservators' caution in introducing new technologies should always be justified; after all, they are responsible for the effects of any activities on the historic objects. This, quite selective review, discusses application of mass spectrometry techniques for the detection of various components that are important to the conservators of our heritage with particular focus on paintings. The text also contains some basic knowledge of technical details to introduce the methodology to a broader group of professionals.

Antimony and Nickel Impurities in Blue and Green Copper Pigments

Impurities in paint layers executed with green and blue copper pigments, although relatively common, have been studied only little to date. Yet, their proper identification is a powerful tool for classification of paintings, and, potentially, for future provenance studies. In this paper, we present analyses of copper pigments layers from wall paintings situated in the vicinity of copper ore deposits (the palace in Kielce, the palace in Ciechanowice, and the parish church in Chotków) located within the contemporary borders of Poland. We compare the results with the analyses of copper minerals from three deposits, two local, and one historically important for the supply of copper in Europe, i.e., Miedzianka in the Holy Cross Mountains, Miedzianka in the Sudetes, and, as a reference, Špania Dolina in the Slovakian Low Tatra. Optical (OM) and electron microscopy (SEM-EDS), Raman spectroscopy, and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) have been used for a detailed investigation of the minute grains. Special attention has been devoted to antimony and nickel phases, as more unusual than the commonly described iron oxides. Analyses of minerals from the deposits helped to interpret the results obtained from the paint samples. For the first time, quantitative analyses of copper pigments’ impurities have been described.

Wall paintings – diagnostic and archaeometric studies

The paper deals with the techniques and protocols used for studying wall paintings. A brief introduction about the more recent literature dealing with archaeometric and diagnostic analyses of wall paintings is reported. After that, the illustration of three case studies, spanning from Roman to contemporary wall painting are described.

Spectroscopic analysis of XIV century wall paintings from Patriarchate of Peć Monastery, Serbia

The Church of the Holy Mother of God Hodegetria in Peć is decorated with wall paintings that date from the beginning of the 14th century. In terms of style they correspond to Byzantine wall paintings from the epoch of Paleologos. The painting technique and pigment pallete has been examined on micro fragments in thin cross-sections by means of optical microscopy (OM), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) and micro- Raman spectroscopy. Use of the fresco technique and two supporting plaster layers was noted on the majority of samples, while in large blue painted areas, a combination of fresco and secco techniques was used. The SEM-EDS results showed the presence of Ca as the main component of plaster besides the traces of Si and Mg. In some samples egg white as a binder was identified. The paint film is often multilayered. Twelve pigments were identified, mainly natural earth pigments such as red ochre, yellow ochre and green earth. A mixture of pigments was used for attaining desirable optical and aesthetical impressions. As decay product only weddelite was detected in many preparatory and painted samples.