Pottery technology in the Tang dynasty (ninth century ad): archaeometric analyses of a Gongyi sherd found at Siraf, Iran

Abstract

In 1969-70, a single Tang dynasty blue-spotted Gongyi sherd was found at Siraf, Iran, the main trading port on the Persian Gulf in the early Islamic period. This is the only known example of Chinese blue-and-white ware, whether low-or high-fired, found in the Middle East from such an early date. The sherd provides direct archaeological evidence for the Indian Ocean trade between China and the Middle East in the ninth century AD. The body paste, clear glaze and blue glaze or pigment were analysed by thin-section petrography, scanning electron microscopy with energy-dispersive X-ray spectrometry (SEM-EDX) and X-ray fluorescence (XRF). The technological analysis reveals the different steps of the chaîne opératoire: clay mixing, slip and glaze application, and decoration with the cobalt blue glaze before high-temperature firing. These steps are characteristic of Tang stoneware production at Gongyi in Henan province, China. The use of cobalt blue pigment as part of a simple spotted decoration scheme on the Gongyi sherd, and its find context within the Middle East, provides evidence for the complex interplay and influence occurring between Chinese and Middle East ceramic industries at this time.Closely comparable examples of contemporary low-fired earthenware ceramics with cobalt blue decoration on a white tin glaze manufactured within the Middle East also occur within the same assemblage from Siraf.

Cobalt and Associated Impurities in Blue (and Green) Glass, Glaze and Enamel: Relationships between Raw Materials, Processing, Composition, Phases and International Trade

“…It is important to note that as early as the Ptolemaic and Roman periods, lapis lazuli was also used as a colouring agent of the glaze and enamels on glass [69][70][71][72][73][74][75]87,88], a fact still today ignored by most scholars. Taking into account that cobalt appears to have been used to colour glass continuously since the late Egyptian/Mesopotamian Antiquity [89][90][91][92][93][94][95][96][97], we should ask why the coloration of glazes with cobalt almost disappeared after the Ptolemaic period up to the Tang Dynasty (8th-Century) in China (at the kilns of Baihe and Huangye, close to Gongyi, in Gongxian, Henan province [98][99][100][101][102][103][104]) and the Umayyad Caliphate (661-750 CE) in Mesopotamia [19]. One reason can be found in the continuous recycling of blue glass proved by many shipwrecks in the Roman [105,106] and to some extent during the medieval period [14,106].…”

Synergistic chemical and structural colorations in early polychromic ceramic glazes over 1000 years ago

“…The pursuit of blue and application of Co pigment are believed to be in uenced by Islamic customs. 53,54 Nevertheless, Fe and Cu still remain as two dominant colouring elements in Tang ceramics, complying with earlier traditions of Chinese glazes. 23 The nely potted Yue kiln wares represented one of glorious periods of Fe coloured celadon glazes.…”

An exploration of potential raw materials for prehistoric pottery production in the Tao River Valley, Gansu Province, China

“…The VP mode enables a wide range of nonconducting samples (such as these fired briquettes) that cannot be examined in a conventional high vacuum SEM to be studied at a range of voltages, without being coated with a thin layer of carbon or gold (see Spataro et al, 2009, p. 39). Ideally, samples to be studied by SEM-EDX should be polished in thick or thin sections to improve the geometry of the sample, but the VP SEM used in this research has already been tested on unpolished surfaces (fractures), and the results are highly reproducible (e.g., see Falcone et al, 2006;Spataro et al, 2009Spataro et al, , 2013Spataro et al, , 2019. This technique is therefore appropriate for obtaining data accurate and precise enough to answer our research questions.…”