Qinglin Ma

In China, bronze swords from the Wu and Yue regions of the Warring States period were renowned far and wide. Their pommels were often decorated with concentric rings, jade, turquoise, and other ornaments. In 2014, a bird‐script Yue‐style bronze sword was unearthed from Tomb M675, Phase III of the Jinding site in Linzi, Shandong. Analytical results indicated that this bronze sword pommel is centrally inlaid with a mammillated lead‐barium glazed pottery bead that was likely produced independently and subsequently set into the pommel. The bead's body is composed primarily of quartz, potassium feldspar, and iron‐bearing clay. The glaze is composed of Chinese Blue dispersed in lead‐barium glass and also contains a small amount of unmelted quartz particles. Within the glassy phase of the glaze, lead (Pb) and barium (Ba) levels are high, with a small amount of potassium (K) detected and no sodium (Na) present, characterizing it as part of the Pb‐Ba system. At the body‐glaze interface, celsian (barium feldspar) formed from the migration and deposition of Ba ²⁺ ions during firing; together with the abundant unmelted crystalline particles preserved in the body and glaze, this microstructure is consistent with a relatively low firing temperature for the bead, probably below 900°C. This study represents the first discovery of a lead‐barium glazed pottery ornament on a Wu–Yue bronze sword, and one that employs Chinese Blue as a colorant. Its composition, craftsmanship, and form provide new scientific information for the study of Wu–Yue bronze swords, reflecting the broad range of decorative applications for artificially synthesized lead‐barium glazed pottery beads during the Warring States period.

Glaze crystallization is a key surface decoration technique in black-glazed ceramics, reflecting the advanced craftsmanship of ancient ceramic production. In this study, a black-glazed ceramic sherd from the Song Dynasty (960-1279 C.E.), excavated in Nanjing, China, was systematically analyzed using optical microscopy, macro-X-ray fluorescence (Macro-XRF) imaging, and field-emission scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (FESEM-EDS) and Raman spectroscopy. The results reveal well-shaped stellate crystals within the cover glaze, which are comprised of oval crystals, brown prismatic crystals, fibrous crystals, and reddish-brown spherical crystals. These crystals are identified as α-cristobalite, rich-Ca and low-Mg hedenbergite [Ca(Mg_0.09Fe_0.89Mn_0.02)Si₂O₆] and rich-Ca spinel ferrite [(Ca₀.₆Mg₀.₄)Fe₂O₄], respectively. A potential growth mechanism for these structures is proposed. The α-cristobalite nuclei serve as a structurally compatible, low-energy substrate for hedenbergite nucleation. Local enrichment of Ca and Fe, combined with liberated SiO₄ units, supplies the components for hedenbergite growth, which proceeds radially as prismatic and fibrous aggregates around the cristobalite core. As crystallization advances, localized Fe enrichment and micro-oxidizing conditions at the hedenbergite-glass interface promote the precipitation of Ca-rich spinel ferrite as submicron spheres intergrown with hedenbergite. Prolonged cooling further enhances this intergrowth, ultimately producing the well-ordered, multilevel stellate structures observed.

Ancient Chinese bronzes, particularly bronze mirrors, often develop a fatty, oily, or greasy film on their surface, known as patina. This film can appear silvery, green, or black. Bronze mirror samples from the Spring and Autumn Period (770–476/403 BCE) to the Ming Dynasty (1368–1644 CE) were analyzed using a systematic approach that included super depth of field three-dimensional microscopy, scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM–EDS), Raman spectroscopy, and THM-Py-GC/MS. The analysis indicates the presence of advanced organic acid lead in the matrix of ancient bronze mirrors. The ancient existence of the lost wax method combined with the mould method of bronze casting technology is verified through simulation experiments and ancient literature. Ancient bronze mirrors may have utilized this technique, with advanced organic acid lead remaining in the mirror mould that entered the bronze mirror matrix during pouring. The Lead organic acids in bronze mirrors readily precipitate on the surface and cover the mirror. The change in the greasy sheen on the surface of the bronze mirror may be related to the degree of corrosion. If the mirror's corrosion level is low, the organic acid lead film remains transparent. If the level of corrosion is significant, the organic acid lead film may darken in color due to oxidation, aging, hydrolysis, or microbial activity.