Introduction

The Ding kiln site, located in Quyang County, Hebei Province, is one of China’s most renowned porcelain kiln sites, famous for producing white porcelain. The kiln reached its zenith during the Northern Song dynasty (960–1279 AD)1, producing some of the finest white porcelains in north China2. Ding wares’ body composition and firing techniques profoundly impacted the development of porcelain technology in subsequent periods, making it essential to understand the history of porcelain manufacturing in China. Plenty of discussions have been conducted on the body recipe of Ding white porcelains3. The Ding wares were typically made by combining kaolin with a flux, though direct historical record regarding the specific flux type used in Ding wares bodies is currently absent4. Many scholars suggest that these fluxes may have included calcium- or potassium-rich materials such as wood ash, dolomite, or limestone1,5,6,7,8, but the flux was used in a relatively small quantity and had a limited impact on the overall composition of the porcelain body9. The significant shift in the body composition of white porcelain during the Song and Jin dynasties is a vital issue worthy of in-depth study10. Several scholars have explored this topic. Cui et al.1 attributed the decrease in CaO content from the late Northern Song to the Jin dynasty to the exhaustion of high-quality clay during this period. Ma et al.11 suggest that the shift in body and glaze composition from the Northern Song to Jin dynasties was related to the wars of the late Northern Song period, which led to skilled ceramic craftsmen leaving the Ding kiln12. Kang et al.8 propose that the change in the body composition of Ding wares during the late Northern Song period may have been related to technological advancements such as replacing wood with coal to fuel kilns. Zhou et al.13 suggests that using potassium-rich materials instead of calcium-rich materials in Jin dynasty Ding wares bodies contributed to increased production efficiency and expanded production scale at the Ding kiln.

The strontium isotope ratio has been extensively employed in this investigation as it can directly reflect the change of flux types. Liu et al.14 determined that the porcelain bodies of Jin dynasty Ding ware utilized high-alumina clay, dolomite, and plant ash as raw materials through a comprehensive study of strontium isotope ratios. However, these studied samples were unearthed from the Wanquansi site in Beijing, and only determined to be Jin dynasty Ding wares based on typological analysis. Ma et al.11 measured the strontium isotopes of Ding ware samples from the Five Dynasties, Northern Song, and Jin dynasties and discussed the types of flux used in glaze of different periods. However, the specific kilns where these samples originated are unclear. Wu et al.10 investigated the types of flux in the porcelain body of Northern Song Ding ware by measuring the strontium isotopes and trace elements of Ding kilns, but the specific kilns from which the Ding ware samples originated remained unclear. Due to sampling issues, there is still a lack of systematic isotopic and trace element data on the white porcelains directly excavated from the Jin period Ding kiln site, leading to an inconclusive understanding of its technology.

In this research, we highlighted the the effectiveness of an integrated methodology including contexualized sampling and detailed geochemial analysis. Trace elements and strontium isotopes were analyzed for Ding kiln white porcelain bodies from Jianci site dated to Early and Late stages of the Jin dynasty. These samples, with clear archaeological context, shed new lights on our understanding of the change in the Ding white porcelain recipe during the Song and Jin dynasties.

Methods

Archaeological setting and excavation of the Ding Kilns

The Ding kiln site is located in Lingshan Town, Quyang County, Hebei Province, primarily concentrated in the villages of Jianci, Beizhen, Yebei, and Yanchuan, covering a total area of ~10 km4 (Fig. 1). The Ding kiln originated in the late Tang Dynasty (782 AD)15 and reached its peak during the Song and Jin dynasties16. Archaeological expeditions at this site began in the 1960s, and decades of archaeological surveys and excavations have revealed that the Beizhen area was the production centre of the Ding kiln during the Tang Dynasty16, while the Jianci area took over during the Northern Song Dynasty and continued to be the production centre for high-quality Ding wares in the Jin Dynasty17. The Yanchuan area was more active during the Jin and Yuan dynasties, with relatively few earlier remains discovered in this region18.

Fig. 1
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Map of the Ding kiln site area, mainly distributed in Jianci, Yanchuan, Yebei, and Beizhen sites.

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In 2009, a joint archaeological expedition excavated four sectors (Jianci, Jianxi, Beizhen, and Yanchuan) of Ding kilns18. The nine excavation trenches at the Jianci site were set in three areas: T2 and T4 in Area A, T1, T3, and T10 in Area B, and T3 and T4 in Area C. The shapes and decorative features of excavated sherds are highly similar to white porcelain artifacts unearthed from Jin period tombs. For example, the fine white porcelain open dish (JCAT4④b:2) exhibits a similar form to Type I white porcelain bowls unearthed from the Jin dynasty tomb M1 (1153–1160 AD) in Haidian, Beijing19 Another fine white porcelain bowl closely resembles, in both shape and decoration, a white-glazed bowl with incised fish design recovered from the Jin dynasty hoard at Nong’an, Jilin Province20. In the early Jin Dynasty, Ding kiln white porcelain was primarily plain-bodied, with smaller sizes and simpler decorations, Incised decoration is neither as abundant nor as refined as that of the late Northern Song period, with most motifs being relatively simple. Dishes with folded rims and incised designs were popular. Traditional decorative patterns such as the “double fish amidst waves”, lotus, and daylily motifs continued to be used from the late Northern Song period. The combination of porcelain types in tombs is relatively stable. Entering the middle to late Jin Dynasty, Ding kiln white porcelain production experienced rapid development. Impressed decoration became the mainstream, and the decorations became increasingly rich and diverse. Plain-bodied wares gradually decreased, while more extensive and finely decorated carved wares emerged21. Combining stratigraphic and stylistic evidence, the white porcelain fragments from this site had been classified into the early Jin Dynasty (1127-1160AD) and the middle to late Jin Dynasty (1161–1219AD), respectively17.

Samples

All the Jin Dynasty white porcelain samples analysed in this study were from Area A (JCA) and Area B (JCB). Twelve porcelain sherds belong to the early Jin dynasty, while six are dated to the late Jin dynasty. Detailed information on all samples is presented in Table 1. Visual examination reveals that these samples are all fine white porcelain with a high level of whiteness (Fig. 2).

Fig. 2: Some representative white porcelain samples from the Ding kiln site.
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a Early Jin Dynasty white porcelain sample from the Jianci A site, b Late Jin Dynasty white porcelain sample from the Jianci A site.

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Table 1 Catalogue of samples
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XRF analysis

All samples were first cleaned with deionized water. They were then mounted in epoxy resin and ground to expose the porcelain body for chemical analysis. A Bruker S2 PUMA ED-XRF, operating at 40–50 kV and 2 mA, with a beam spot of 1 mm in diameter, was used to determine their chemical composition. A calibration curve for eight oxides usually presented in porcelain (SiO2, Al2O3, Na2O, K2O, MgO, CaO, Fe2O3, TiO2) was developed with seven standards (see Fan et al.22 for more details of this method). The standard samples utilized in the measurement are shown in Supplementary Table S1. Test results for the eight oxides are normalized to 100 wt%.

Isotope and trace element analyses

The trace element and isotopic analyses were conducted at Beijing Createch Testing Technology Co., Ltd. A 0.5 mm micro-drill was used to extract a 200 mg sample from the porcelain body, allowing for independent testing of the trace element composition and strontium isotope ratio. To prepare samples for ICP-MS analysis, ~150 mg of powdered material was dried at 105 °C for 2–4 h. Subsequently, the sample was digested in a Teflon bomb using a mixture of concentrated HNO3 and HF at elevated temperature and pressure. After digestion, the solution was diluted with 2% HNO3 and spiked with an internal Rh standard (GSR-2,GSR-3,GSR-5, See Supplementary Tables S2 and S3 for detailed data). For Sr isotope analysis, ~50 mg of sample powder was digested similarly. The resulting solution was purified using a standard chemical separation procedure. The Sr isotope ratios were measured using a Thermo Fisher Scientific Neptune Plus MC-ICP-MS, and the 87Sr/86Sr ratios were corrected for mass fractionation. The sample for the strontium isotope measurement standard is NBS 987 with a reference value of 87Sr/86Sr = 0.710249 ± 13 (2SD, n = 17). All sample preparation steps were conducted in a clean laboratory environment to minimize contamination. More information can be found in Wu et al.10.

Results

Main oxide content of Ding ware bodies

The results presented in Table 2 indicates slight variation in the chemical compositions of Jin dynasty white porcelain samples from different areas and periods (Fig. 3). These porcelain bodies exhibit a relatively high average Al2O3 content of around 25 wt%. The SiO2 content ranges from 60 wt% to 73 wt%, averaging around 65 wt%. The Fe2O3 and TiO2 contents of porcelain bodies are relatively low, with average values of 0.93 wt% and 0.70 wt%, respectively. The alkaline earth metal oxides CaO and MgO have average contents of 2.90 wt% and 1.88 wt%, while the alkali metal oxides Na2O and K2O have average contents of 0.79 wt% and 1.72 wt%. Principle Component Analysis (PCA) shows that the early Jin samples are generally rich in Al2O3 than late Jin samples (Fig. 3).

Fig. 3
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PCA of primary oxide content in Ding ware bodies from the Early and Late Jin Dynasties (E for the early Jin dynasty, L for the late Jin dynasty).

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Table 2 Bulk chemical composition of Ding ware bodies
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Trace elements content of Ding ware bodies

Supplementary Table S2 includes trace element data of all samples. The trace element scatter plots indicate that the Early and Late Jin samples are significantly different from each other in terms of Sr, Rb, Sc, V, Ba, Nb, and ∑REE concentration as well as V/Ga, La/Sm, and Zr/Hf ratios (Fig. 4a, c). The rare earth elements (REE) are normalized to the chondrite values published by Sun and McDonough23 (Fig. 4b). All samples show a rightward trend but the early and late Jin samples have quite different ∑REE values. The early Jin samples have a ∑REE value between 64.16 ppm and 182.34 ppm, while the late Jin samples have this value fluctuating between 163.00 ppm and 224.27 ppm. The La/Sm ratio of Early Jin Dynasty samples ranges from 2.60 to 4.67, while that of Late Jin Dynasty samples falls within a range of 4.12 to 4.88. Therefore, all trace element data point to a separation between Early and Late Jin samples.

Fig. 4: Trace elements pattern of Ding kiln samples from different stages.
figure 4

a Scatter plot of trace element contents of Early and Late Jin dynasty Ding ware bodies. b REE distribution curve. c Scatter plot of REE-La/Yb. This shows a separation between white porcelain samples from the Early and Late Jin dynasties, while Early Jin samples from JCA and JCB kilns share similar characteristics.

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Strontium isotope analysis of Ding ware bodies

The 87Sr/86Sr ratios of the Ding ware porcelain bodies from the Jin Dynasty range from 0.71600 to 0.72388, while the 87Rb/86Sr ratios range from 2.00762 to 7.42469 (Table 3). As 87Sr is the product of the beta decay 87Rb, the 87Sr/86Sr of minerals usually shows a linear correlation with their 87Rb/86Sr value. The line, customarily called an isochron, defines the formation age of rock and cogenetic clays22,23. On the other hand, when two materials (end members) with different 87Sr/86Sr and Sr contents are mixed in various ratios, the 87Sr/86Sr of the mixture would form a mixing line against 1/Sr24. The mixing line is widely employed in the archaeological context to interpret the geological nature of raw clay and the potential fluxing reagent used in the porcelain-making process25,26.

Table 3 Rb-Sr data of Ding ware bodies during the Jin Dynasty
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The scatter plots of 87Sr/86Sr-87Rb/86Sr and 87Sr/86Sr-1000/Sr (Fig. 5) both separate the Early and Late Jin samples into two clusters. The early Jin samples have much lower Sr content, while the isotopic variations between the two groups are relatively small. Additionally, the early Jin Dynasty Ding ware samples from both the JCA and JCB regions are located on the right-hand side of the plots, suggesting a certain degree of homogeneity among the early Jin Dynasty Ding wares from these two regions.

Fig. 5: Distinct strontium isotopic compositions between Early and Late Jin dynasty Ding ware bodies.
figure 5

a Scatter plot of 87Sr/86Sr-1000/Sr for Early and Late Jin dynasty Ding wares bodies; b Scatter plot of 87Sr/86Sr-87Rb/86Sr for Early and Late Jin dynasty Ding wares bodies.

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Discussion

For comparative purposes, we incorporated the analytical data of Northern Song samples reported by Cui et al.1 and Li et al.27, along with strontium isotope data of raw materials (wood ash, dolomite, limestone, feldspar) near the Ding Kiln, obtained from Ma et al.11. The data on Ding kiln lead/silver smelting crucibles is from Wu et al.10, who argued that these crucibles represent the characteristics of the porcelain clay used at the Ding kiln.

Principal component analysis of major oxide components indicates that the Northern Song and Early Jin samples cluster together but are separated from the late Jin samples (Fig. 6a). The late Jin samples tend to have higher CaO and MgO contents and lower Al2O3 than the others. Trace element scatter plots also show that the Northern Song samples are similar to the early Jin Dynasty samples in terms of Sr, Rb, Hf, and ΣREE contents, as well as V/Ga, La/Sm, and Zr/Hf ratios (Fig. 6b). The late Jin samples however have much higher Sr and ΣREE contents. These findings demonstrate a continuity between the Northern Song and early Jin periods and a clear break between the Early and Late Jin periods.

Fig. 6: Principal component analysis reveals compositional distinctions between Ding kiln porcelain bodies from different periods.
figure 6

a and b show the PCA scores and trace element compositions of porcelain bodies from the Northern Song, Early Jin, and Late Jin Ding kilns. These figures clearly illustrate that the porcelain bodies from the Northern Song and Early Jin periods cluster together, while those from the Late Jin period form a distinct group. (D-NS indicates the Ding Ware samples from the Northern Song Dynasty.)

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The nature of the flux used in the porcelain body of Ding kiln white porcelain from the Song and Jin Dynasties remains a topic of scholarly debate, with researchers offering differing interpretations based on compositional and archaeological analyses. It is widely acknowledged that the Ding kiln in the Song Dynasty inherited ceramic-making traditions from the Tang and Five Dynasties periods28, and it is generally believed that fluxes such as dolomite or other CaO-rich materials were employed during this time1,10. In contrast, interpretations of the Jin Dynasty period show greater variability. Zhou et al.6 suggested that the porcelain body of Jin Dynasty Ding wares were manufactured with clay and rock-type materials in approximately equal proportions. Liu et al.14 proposed a three-component raw material system consisting of high-alumina clay, dolomite, and plant ash. Kang et al.8 emphasized a mineralogical composition dominated by kaolinite, quartz, and illite in the early Jin Dynasty wares, implying a clay-based recipe. Meanwhile, Cui et al.1 argued that the porcelain body might have incorporated either small amounts of calcium-containing raw materials or naturally calcium-rich clays.

These diverse interpretations reflect an evolving understanding of raw material selection and technical choices in the production of white porcelain at Ding kilns, particularly during the transitional period between the Song and Jin Dynasties. However, existing studies have yet to reach a consensus on the precise nature and role of the flux, a key component that significantly influences sintering behaviour and final product quality. This debate is not merely technical but holds broader implications for understanding the technological evolution of Chinese ceramics. In the history of ceramic technology, the introduction and refinement of fluxes—materials that lower the firing temperature and promote vitrification—represent a major technological innovation. The composition and choice of fluxes directly influenced not only the firing temperature and efficiency but also the translucency, strength, and whiteness of porcelain bodies. During the Jin Dynasty, notable changes appear to have occurred in the types and proportions of fluxes used in Ding ware, reflecting a broader shift in raw material procurement, technological adaptation, and possibly aesthetic or functional requirements. Situating the flux-related transformations of Ding kiln white porcelain within this broader trajectory helps to elucidate both the regional dynamics of ceramic technology and the micro-level choices made by artisans. Thus, compositional data derived from scientific analyses can contribute significantly to resolving long-standing debates and deepening our understanding of historical innovation in ceramic craftsmanship.

The Sr isotopic ratios of clay deposits are determined by the geological history of their source rocks and thus can be used to distinguish between different sources of ceramic raw materials29. Plotting the 87Sr/86Sr-87Rb/86Sr data for Jin and Northern Song samples as well as crucibles (Fig. 7a), shows that the Early Jin samples fall close to the Northern Song samples, while the Late Jin samples fall on the extension of the crucible trend line. This indicates that the Early Jin and Northern Song porcelains share similar paste characteristics, while the paste of Late Jin white porcelain is more similar to that of the original Ding kiln clay represented by the crucible. Furthermore, the mixing line shown in the 87Sr/86Sr-1000/Sr scatter plot (Fig. 7b) reveals an overlap between the Late Jin dynasty samples and the crucibles, further indicating that the body composition of Late Jin dynasty Ding ware is more similar to the original Ding kiln clay represented by the crucibles. The trace element scatter plot (Fig. 7c) also exhibits this phenomenon.

Fig. 7: Strontium isotope ratios and trace element data reflect raw material variation in Ding ware production.
figure 7

a Scatter plot of 87Sr/86Sr and Rb/Sr ratios of Ding ware bodies during the Jin Dynasty and Northern Song Dynasty; b Scatter plot of 87Sr/86Sr-1000/Sr ratios of Ding ware bodies during the Jin Dynasty and Northern Song dynasty, as well as for wood ash and dolomite from the surrounding area of the Ding kiln site. c Scatter plot of trace element composition for Ding ware porcelain bodies from the Early and Late Jin Dynasty, as well as crucibles.

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The eastern flank of the Taihang Mountains, where the Ding kiln is located, is with extensive outcrops of limestone, primarily of Ordovician age. The North China Platform, a geological unit covering much of central North China, was a marine environment during the Ordovician period, and the limestones in this region were deposited in that ancient sea. A notable feature of these Ordovician limestones is that they have commonly undergone varying degrees of dolomitization. As a result, a significant portion of the limestone in this area has been transformed into dolomitized limestone or dolomite. According to Zhang et al.30, the Sr concentrations in limestone, dolomitized limestone, and dolomite in this region range from 79 to 296 ppm, considerably lower than the global average for limestones (~460 ppm). This supports the interpretation that Sr is lost during the dolomitization process11. The strontium content of Late Jin dynasty porcelains is significantly higher than that of Early Jin samples (Fig. 7b), suggesting a change in the primary flux material. Early Jin porcelains, which share similarities with those from the Northern Song period, were likely produced using locally available dolomite as the main flux. In contrast, the Late Jin samples are isotopically closer to local clays, indicating that dolomite was less commonly used as a flux during this period. Wood ash contains high levels of CaO, with an average content of 57.14 wt%31. The Sr concentration in plant ash is also high and varies greatly32, plant ash collected near the Ding kiln site has Sr concentrations ranging from 1218 to 2019 ppm, with an average of 1523 ppm11. Furthermore, the 87Sr/86Sr ratios of various Chinese wood ashes fall within a narrow range, averaging around 0.710433. Therefore, the addition of plant ash is unlikely to cause the Sr isotopic composition of the porcelain body to resemble that of the Late Jin Period.

In conclusion, the differences observed between porcelain bodies can be attributed to a higher proportion of dolomitic flux in the Early Jin period, consistent with practices during the Northern Song. By the Late Jin period, however, there was a shift toward relying more on the original raw clay. This transformation may reflect reduced access to high-purity dolomite resources due to political, economic, or environmental changes. Porcelain workers may have adjusted their production recipes in response to shifts in raw material availability or in pursuit of improved cost-efficiency.

At the end of the Northern Song Dynasty, the Jin Dynasty invaded and occupied the current Hebei Province, where the Ding kiln was located. Following the Jingkang Incident (靖康之役) in 1127AD, the production of Ding ware experienced a temporary disruption but quickly resurrected. The region of Zhongshan prefecture, where Ding kiln site is located, rapidly recovered under the Jurchen’s revitalization policies, and the Ding kiln captured a substantial portion of the northern porcelain market34. Production at the Ding kiln had returned to its normal scale by the first year of Emperor Shizong’s reign (1161 AD)35. The ceramic technology of the Early Jin Dynasty Ding ware was based on that of the late Northern Song period, and products exhibit strong similarities in shape and decoration21, indicating a direct continuation from the Northern Song period. Li and Bi36 believe that the decline of the Ding kiln began in the late Jin Dynasty. During this period, potters began to adopt a more economical stacking firing process, which involved scraping off the glaze on the inner bottom of the porcelain to prevent the vessels from sticking together and stacking wares in the kiln for firing. At the same time, the porcelain was made without any decoration. The current study found a similar trend in terms of raw materials. To reduce costs and increase efficiency, potters were probably forced to use simple formulas without flux, even though this recipe inevitably compromised the quality of the porcelain.

Our research indicates that Early Jin Dynasty Ding wares are geochemically similar to the Northern Song Ding wares, indicating a continuation of porcelain production techniques and material choice in this transitional period. Dolomite type material was probably used as a flux. By the Late Jin Dynasty, to improve the production efficiency and lower the costs, potters began to adopt a simpler porcelain making recipe. Plant ash, previously proposed as a major flux of Jin wares, is argued to not be used according to the geochemical results. It is tentatively proposed a flux-free clay was probably used in this period for porcelain production. The change of recipe would result in an inferior quality of the late Jin Dynasty Ding wares in comparison to the Song Dynasty ones, marking the decline of Ding kiln porcelain production.