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

Abstract

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.

Pigments, Dyes and the Restoration History of the Painted Figurines of the Tang Dynasty from the Astana Tombs Revealed by Comprehensive Chemical Analysis

“…However, due to the scarcity of sources, it was believed that lazurite must be imported from Afghanistan via the Silk Road [21] . Therefore, mixing indigo with lazurite as a blue pigment can obtain a special blue hue while reducing the cost, highlighting the wisdom of Gaochang craftsmen in the Tang Dynasty.…”

Coupling of SEM-EDX and Raman spectroscopy to investigate painted preparation layers on two wooden statuettes from Ptolemaic era

“…As shown in Figure 10a the Raman spectra of the preparation layers applied on the statuette no. 1408 presented a strong peak at 1008 cm -1 that is nearly identical to the symmetric stretching of SO 4 tetrahedra, the peak of gypsum's strongest Raman spectra (26). In the Raman spectra of the preparation layer of statuette no.…”

Things Always Come in Three: Non-Invasive Investigations of Alexander and Roxane’s Wedding Room in Villa Farnesina

“…[8] , hematite [10] CaCO 3 [8], silicates [13] and acrylic resin [14] Hematite-based purple, possible caput mortuum [15] Purple/greyish Ca, Fe, Co, K, Si, As, Bi, Sr Ip:589,640,690 nm CaCO 3 [8], hematite [10] Hematite-based purple, possible caput mortuum [15] [8] CaCO 3 [8], weak signal of lapislazuli [20], acrylic resin [14] Lapislazuli from Vis-R [12] and traces of restoration materials Ca, Fe, Co, As, K, Si, Sr, Bi Max:480 nm, Min:595 nm, Ip:680 nm Lapislazuli and smalt [16] in different superimposed layers. From Vis-R only Lapislazuli [12] Ca, Fe, Co, As, K, Sr, Bi Max:481 nm, Min:541,590,637 nm, Ip:680 nm Lapislazuli [12] and smalt [16] [8] Smalt [16] In the red areas, the presence of Fe-based pigments prevails (Table 1). In the darker shades, Raman spectroscopy identified red ochre, with the addition of a few hematite (Figure 4a, right, line 2).…”