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The rise of porcelain industry in northern China and the subsequent emergence of white porcelain production during the Northern dynasties (386–581 CE) played a pivotal role in shaping the historical trajectory of Chinese ceramics. Xing kiln is one of China's earliest and most representative white porcelain kilns. Herein, we investigated 23 porcelain sherds from the Neiqiu Xing kiln site during the late Northern dynasties and the early Sui dynasty (550–600 CE) from the perspective of firing temperature, firing atmosphere, and microstructure using a dilatometer, X‐ray photoelectron spectroscopy, and scanning electron microscopy. The results show that the early Xing porcelains were fired at high firing temperatures exceeding 1200°C with a reducing flame, and the adjustment of temperature promotes the emergence of early white porcelain. Moreover, the higher firing temperature of early Xing porcelain leads to the dominance of a glassy phase within the glaze, and the high bonding strength of the glaze and body caused by the body–glaze interaction layer formed with dense anorthite crystals. Overall, these findings provide valuable insights into the firing technology in the Xing kiln and even in North China during the late sixth century. [ABSTRACT FROM AUTHOR]

Dalian Island, located in the northwest of Pingtan County, Fujian Province, China, has been an important junction on the Maritime Silk Road since the Tang dynasty. This study focuses on sauce-glazed ceramic ware from the Song dynasty salvaged from the waters near Dalian Island Wharf. The composition, phase attributes, and microstructures of the marine organism remains attached to the ceramic ware were analyzed using an optical microscope, scanning electron microscope, and micro-Raman spectrometer to investigate the influence of marine organisms on the degradation of the ceramic ware. Long-term abrasion by sea wave-borne debris led to the increased surface roughness and wettability of the ceramic ware, facilitating the attachment of marine organisms. Differences in surface roughness between the inner and outer walls led to varying levels of biomass. Coralline algae secreted inducers to attract the larvae of macrofoulers. The attachment of different types of marine organisms had varying effects on the degradation of the ceramic ware. Firmly attached unitary organisms could alleviate the scouring of sea wave-borne debris and hinder the intrusion of foreign pollutants, thereby playing a 'bio-protective' role. In contrast, the group skeletons of modular organisms could reinforce the mechanically damaged surface but failed to block the intrusion of iron rust and other pollutants, resulting in chemical alterations of the glaze. Therefore, the specific species of the attached marine organisms should be considered in subsequent conservation efforts. [ABSTRACT FROM AUTHOR]

As the criterion used by archaeologists for determining early white porcelain is quite ambiguous, the origin of Chinese white porcelain remains a point of disagreement. In this study, we systematically investigate 61 typical Xing porcelains of the late Northern dynasties to the early Sui dynasty (550–600 CE) using spectrophotometer, X‐ray fluorescence (XRF), scanning electron microscopy (SEM), and X‐ray powder diffraction (XRD), and analyze the differences between early white porcelain and celadon of Xing kiln in terms of their whiteness and raw materials characteristic. The results show that early white porcelain is a new type of ware that differs from celadon, which can be distinguished by whiteness, with a whiteness greater than 8% being early white porcelain and a whiteness less than 8% being celadon. It is assumed that the ancient potters created the whiter wares based on celadon by improving the glaze and selecting new raw materials for the body, but the production of this type of ware was short lived and subsequently refined in the Sui dynasty (581–618 CE) owing to the limited improvement in whiteness. [ABSTRACT FROM AUTHOR]

Dalian Island is located in the sea area near Pingtan County, Fujian, Southeast China. The sea area used to be the junction of the eastern and western ship routes on the Maritime Silk Road, and is also an important region for underwater archaeology in China. This study focused on a sauce-glazed ware of the Song Dynasty, with serious degradation, which was salvaged out of the water at the Dalian Island Wharf. Optical microscopy, scanning electron microscopy, X-ray diffraction analysis, and micro-Raman spectroscopy were used to comprehensively analyze the composition, phase attributes and microstructure of the ware and the surface-attached coagula. The findings revealed that the sea wave-borne debris scoured the surface of the ware, causing mechanical damage to varying degrees and a significant decrease in its degradation resistance. This was the primary factor accounting for the poor preservation state of the salvaged ceramic ware, and the precondition for the subsequent attachment of marine organisms and the deposition of inorganic pollutants. The calcareous skeletons formed on the surface induced by the bio-mineralization of coralline algae (a type of marine plant) could resist the mechanical action caused by the motion of sea waves, thereby slowing down the ware's degradation process. In other words, the calcareous skeletons played a 'bio-protective' role to a certain degree. In addition, inorganic pollutants represented by iron rusts also participated in the corrosion of the glaze. Some pollutants were directly deposited on the pits and cracks on the surface of the ware, which brought stress to the glaze and glaze/body interface, causing the glaze to further crack and spall. Moreover, iron rusts reacted with the glaze, leading to chemical alteration, accompanied by the formation of iron silicate as the alteration product. Anorthite crystals in the interlayer did not participate in the reaction but remained at the original position. The alteration product gradually replaced the original glass phase of the glaze and entered into the body via pores and cracks. In conclusion, the complex degradation morphology of the salvaged sauce-glazed ware could be attributed to the combined action of mechanical damage, marine bio-fouling, and chemical alteration. [ABSTRACT FROM AUTHOR]

Eleven celadons with different degrees of degradation excavated from the Dalian Island shipwreck of the Yuan Dynasty (1271–1368 AD) were selected, and the degradation mechanism of the ancient porcelain at marine environment was investigated. The chemical composition, microstructure, and corrosion morphology of the samples were characterized. The results showed that these celadons can be divided into two types: transparent glazes and matt-opaque glazes. The glazes are subject to the combined effects of physical damage and chemical corrosion. The glaze surface became rougher through physical impact, and the increased surface area may also promote chemical corrosion. The mutual promotion of the two effects usually leads to more serious degradation. There are two possible corrosion mechanisms, depending on the glaze microstructure. Transparent glazes may experience the process of dissolution and reprecipitation. The crystallization-phase-separation structure in the matte glaze has lower chemical stability, which can contribute to more extensive corrosion. [ABSTRACT FROM AUTHOR]

The Dalian () Island shipwreck of the Yuan Dynasty (1271–1368 CE) was located in the sea area of Pingtan (), Fujian () Province, China. A total of 603 Longquan () celadon wares were excavated, some of which have been severely corroded. In this study, two celadon specimens with severe corrosion were selected to investigate the corrosion mechanism in the marine environment. Optical microscopy (OM), scanning electron microscopy equipped with energy dispersive X-ray spectrometry (SEM–EDS), X-ray diffraction analysis (XRD), Micro-Raman spectroscopy, and thermal expansion analysis were applied to analyze the microstructure of the glaze, corrosion morphology, and composition of corrosion products, and the corrosion mechanism was discussed in depth. The results showed that these two celadon wares are opaque matt glaze, in which the anorthite crystallization-phase separation structure with low chemical stability was found, which was more likely to be corroded. There are three possible stages in the corrosion process of the glaze. The first stage is mainly the long-term cation exchange reaction. Then, because of the corrosion of the CaO-rich droplet phase and the crystal-glass phase interface layer, the porous structure and many microcracks may be formed, promoting the corrosion process. Finally, many corrosion craters, caused by the shedding of anorthite crystals, may appear on the glaze surface. The quintinite group minerals in the glaze were probably formed during the corrosion process, which may be related to the marine buried environment and the corrosion of the glaze. This study discussed the influencing factors of the corrosion process of celadon wares in the marine environment from the perspective of microstructure for the first time, which is of great significance to the study of the corrosion mechanism of ancient ceramics. [ABSTRACT FROM AUTHOR]

A glaze slip made from a mixture of porcelain clay and flux was melted at high temperatures to form an amorphous glaze layer on a ceramic body. All information about the raw materials and recipes of the glaze was lost in this process, leading to difficulties in the reconstruction of the ceramic-making process performed in ancient China. Herein, the refiring experiment was performed and the thermal dilatometer (DIL), X-ray diffractometer (XRD), X-ray fluorescence (XRF) and field emission scanning electron microscope (SEM) were utilized to investigate the crystallization behavior in the glazes of an underfired Jizhou tea bowl. The results showed that diopside, fluorapatite, and anorthite crystallized from the heterogeneous glaze slip, induced by the inhomogeneity of the raw materials and the incomplete mixing process, during the firing process in the glazes of the Jizhou tea bowl. All these crystals melted with increasing temperature, indicating the importance of the underfired samples in reconstructing the ancient ceramic-making technique. Diopside and fluorapatite could be potential fingerprints to identify the usage of botanic ash in the glaze recipes. [ABSTRACT FROM AUTHOR]

• The angle dependence phenomenon of Jian bowl colors was classified into two types. • The first type of coloring mechanism is assumed to be coherent light scattering by an amorphous photonic structure formed during the firing process, which has weak angle dependence. • The second type of coloring mechanism is thin-film interference, which has obvious angle dependence and is closely related to the corrosion process of Jian bowls in the burial environment. Jian bowl is generally known for its artistic appearance such as hare's fur and oil spots caused by the crystallization of iron oxides on the glaze surface. While very few Jian bowls have angle-dependent colors, scientific research on the topic is lacking owing to the scarcity of relevant samples. In this study, the angle-dependent colors of Jian bowls were systematically studied using various characterization techniques, such as angle-resolved reflectance spectra, X-ray diffraction, micro-Raman, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic force microscopy. The angle dependence phenomenon of Jian bowl colors was classified into two types, and the coloring mechanisms were clarified. The first type of coloring mechanism is assumed to be coherent light scattering by an amorphous photonic structure formed during the firing process, which has weak angle dependence. The second type of coloring mechanism is thin-film interference, which has obvious angle dependence and is closely related to the corrosion process of Jian bowls in the burial environment. [ABSTRACT FROM AUTHOR]