Datong, located in the northern of Shanxi province of China, has an important transportation hub, connecting the Central Plains and Inner Mongolia. Various cultures converge in Datong and form rich aesthetics, reflecting in the famous carving black-glazed wares produced during Jin and Yuan Dynasties in Hunyun kilns located in Hunyuan county, Datong. The carving wares are characterized by gray-white body decorated with carved black glazed patterns. Such a gray-white and black contrast gives the patterns a relief-like decoration. Many researches were devoted to analyze regional features, decorative themes and technology of black-glazed carved wares by conventional archaeological methods. Wang et al. investigated one piece of black-glazed carved ware by micro-Raman spectroscopy and found a large number of ε-Fe₂O₃, a few hematite and magnesio-ferrite on the glaze surface, leading to the brown tune of the carved black patterns. However, the lack of the microstructure, chemical and mineral composition of carved black-glazed wares leads to the raw materials and firing protocol of black glazed carving wares, and its relationship to ordinary pure black glazed is still unclear. In this work, carved black-glazed wares and pure black glazed wares of Hunyuan kilns were investigated by a series of analytical techniques. The characteristic of raw materials and firing protocol of black glazed carving ware and its relationship to black glazed ware were discussed.

Eleven fragments were excavated from Jiezhuang village, Hunyuan county, Datong, China, which could be dated to Jin and Yuan Dynasties according to the archaeological layer. The fragments were prepared as cross-sections by a cold mounting method. The details were described in elsewhere. The morphology, chemical composition, mineral composition and valence state of colorant elements of glaze and body were measured by a model VXH-7000 optical microscope (OM, KEYENCE Co., Japan), a model XGT-7200 X-ray fluorescence (XRF, Horiba Co., Japan), a model Renishaw-invia micro-Raman spectroscope (micro-RS, UK), a model TD3500 Macro-X-ray diffracometer (macro-XRD, Dadong Co, China) and a model Axis Supra X-ray photoelectron spectroscope (XPS, Shimadzu Co., Japan).

The results by XRF analysis show that the raw materials used for glazes and bodies of carved black-glazed wares and pure black-glazed wares are similar except for the glaze of former, which is much richer in CaO. A higher CaO can enhance the adhesion of the glaze and body. Besides, the bodies are composed of higher TiO₂ and lower MnO₂ and Fe₂O₃ rather than the glazes, leading a gray-white and dark black contrast between the bodies and glazes. The glaze surfaces contain massive dendrite ε-Fe₂O₃ crystals and a few of hematite, magnetite and magnesioferrite. A few of zircon, anorthite, pseudobrookite and quartz appear in the glaze cross-sections. The bodies contain cristobalite, quartz and mullite. There is no obvious difference in the raw materials of carved black-glazed wares and pure black-glazed wares. The degrees of the glassy polymerization (I_p) of carved black glaze and pure black glaze are similar, i.e., 1.34–2.25, which are consistent with the glaze modifiers/network formers mole ratios, i.e., 0.12–0.2. The similar I_p values and mole ratios indicate that the wares both are prepared at the similar firing temperature. Most of carved-black glazed wares and black glazed wares present the similar ratios of iron bivalence and trivalence, i.e., 2.0–2.6, indicating that the wares both are prepared in a reductive atmosphere. Besides, the Raman spectra of the dendrite ε-Fe₂O₃ crystals show an obvious shift to s higher wavenumber possibly due to the lighter ions substituting irons in the crystals to improve their stability. Moreover, the spectra also present different intensity of Raman features, accounting for the different crystal orientation of these crystals. Such a different orientation can make the dendrite crystals react with incident lights in diffractive or reflective function, giving rise to the glaze surface presenting iridescent or silvery effect.

The similar raw materials were used for preparing the carving black-glazed wares and pure black glazed wares expect for the slightly higher CaO in the glazes of carved black glazes. The bodies were composed of higher TiO₂ and lower MnO₂ and Fe₂O₃ rather than the glazes, leading to a gray-white and dark black contrast between the bodies and glazes. The wares both were fired at the similar firing temperature and in a reductive atmosphere. The main minerals of the bodies were cristobalite, quartz and mullite. Numerous dendrite crystals in micron-size with different crystal orientation were distributed in the glaze surfaces, which could react with incident light in diffractive and reflective functions, leading to the glaze presenting iridescence or silver. Besides, a few of magnetite, magnesioferrite, zircon, anorthite, pseudobrookite and quartz were detected in the glazes.