The Afrasiab murals discovered in the northeast of Samarkand, Uzbekistan—the center of the ancient Silk Road—are presumed to date to the mid-seventh century during the Sogdian era. Although previous studies have examined the primary materials of the pigments used in these murals using chemical and microscopic analyses, in-depth investigations of the pigment raw material composition have not been conducted to verify the results of these studies. We applied X-ray diffractometry, Raman spectroscopy, and scanning electron microscopy in conjunction with energy-dispersive X-ray spectroscopy for the first time to identify the raw materials of ancient pigments in fragments obtained from the Afrasiab murals. The results show that lazurite, cinnabar, and amorphous carbon were used as blue, red, and black pigments, respectively. Moreover, we identified that pigments were not directly painted on the wall surface; instead, they were painted on a white undercoat of gypsum plaster, similar to other ancient Silk Road wall paintings. The results of this study can benefit the provision of more accurate information with regard to the composition of raw materials and further support the selection of appropriate substances for the purposes of conservation and restoration of Afrasiab murals.

Ancient Pigments in Afrasiab Murals: Characterization by XRD, SEM, and Raman Spectroscopy

Abstract Teotihuacan, the main city of the Classic period in Central Mexico ( ca. 150/200–650 CE), was among many things, a colorful city. Through its application on mural painting, ceramics, lapidary, bone, textiles, and the human body itself, coloring materials gave meaning to the Teotihuacan reality. This research presents color as a socio-technological phenomenon from the archaeology of color, the anthropology of technology, and the application of the concept of technological style. From this scope, pictorial palettes of mural painting fragments from three Teotihuacan architectural compounds were studied by digital microscopy, colorimetry, fiber optic reflectance spectroscopy (FORS), X-ray fluorescence (XRF), Raman spectroscopy, infrared spectroscopy (FTIR), and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) in order to identify the color technology of pigments. This approach led us to identify materials shared by the three studied compounds, red and yellow earths, cinnabar, malachite, pseudomalachite, azurite, and the Teotihuacan grayish blue, found to contain a mix of bone black with calcite. Our results contribute to the discussion on the use of raw materials and their mixtures. We observed a standardization of pigment technology in Teotihuacan mural painting through the use of shared and standard formulations with four indicators that we propose as markers of a technological style for pigments, along with variations in the color materials that evidence the use of different strategies for the procurement and distribution of raw materials among the diverse architectural assemblages of the city. 

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New insights on Teotihuacan color technology: a proposal of a technological style for mural painting

The detection of trace binding medium in wall paintings is usually challenging due to the aging and degradation of proteinaceous binding medium in a long time. Therefore, immunomagnetic beads (IMBs) with specific enrichment ability for casein and ovalbumin were prepared, and then the beads were applied for capturing target proteinaceous binding medium from ancient Chinese wall paintings. After optimization of experimental conditions, the enrichment performance of magnetic beads was confirmed by enzyme-linked immunosorbent assay (ELISA) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). In this experiment, archaeological wall painting samples were used to verify the accuracy of the construction enrichment method. The results showed that the OD450nm value of archaeological samples containing binding medium has increased to varying degrees after IMBs enrichment, effectively avoiding the occurrence of false negative results, indicating that the IMBs enrichment method developed in this work could be successfully applied for enriching ovalbumin and casein binding medium from ancient wall paintings for subsequently immunoassay detection. 

High‐performance enrichment of casein and ovalbumin in wall painting with immunomagnetic beads

Techinantitla building complex, in the Amanalco neighborhood of the ancient city of Teotihuacan, is famous for the iconography and quality of the mural paintings found in this site. A significant part of this heritage has been lost due to looting. In recent years, an interdisciplinary research project was developed to study the limited patrimony that was left. As part of this study, we first employed geophysical techniques to reconstruct the architectural pattern of the compound’s remaining walls, where other paintings may still be found. Then, we applied a non-invasive methodology to characterize a large set of fragments recovered in the 1980s and to gain information on their pigments and manufacturing techniques. This methodology included False Color Infrared Imaging, X-ray Fluorescence and Fiber-Optics Reflectance Spectroscopy, and led to the identification of hematite, calcite, malachite, azurite and an unidentified blue pigment. The results were compared with a previous study performed on a set of Techinantitla mural paintings looted in the 1960s. A broader comparison with contemporary mural paintings from other Teotihuacan complexes shows good agreement in the materials used. These results may suggest a standardization in the making of Teotihuacan mural painting during the Xolapan period (350 to 550 AD).

Luis Barba

Papers

Analytical Approach for the Study of Teotihuacan Mural Paintings from the Techinantitla Complex