The birth of copper-red glaze: Optical property and firing technology of the glaze from Changsha Kiln (8th–9th century)

Changsha Kiln rose and flourished alongside the development of China's Maritime Silk Road (8th–9th century). The kiln occupies an important place in the development of China's ceramic science and technology, notably as the source of high-temperature copper-red glaze. A variety of lime-colored glaze was one product of Changsha Kiln. Its surface was decorated with both copper-green and copper-red, and is the earliest known example of the successful firing of a copper-red glaze. This ware is representative of the birth of high-temperature copper-red glaze, but there has been a lack of research on its optical properties and the technology’s origin. In this paper, OM, SEM, TEM, optical coherence tomography (OCT), XRF, fiber optic spectrometry, and other analytical techniques were used to investigate the red and green glazes of Changsha Kiln. The key result of this paper is to reveal the optical properties of copper-green and copper-red in combination with colloidal absorption, ion absorption, and scattering, and to study the key factors for the origin of the high-temperature copper red glaze.     

Influence of firing temperature on the color developed by a (Zr,V)SiO4 pigmented opaque ceramic glaze

The analysis of the physical interactions between pigments, opacifiers and glazes is fundamental to understand the optical behavior of ceramic glazes. Furthermore is important to verify if the glaze devitrifies because the crystallized phases can contribute to the optical properties of the system. The size and the quantity of the formed crystals can change significantly the glaze color. The mean goal of this study was to evaluate the influence of firing temperature on the color stability of an opaque ceramic glaze colored by a blue vanadium–zircon pigment taking into account all the optical components. Quantitative X-ray diffraction analysis was conducted in order to evaluate the pigment dissolution at the three studied temperature and the quantity of the in situ formed zircon crystals from the used frit. The reported study demonstrated the importance to consider all the components in a multicomponent optical system as a ceramic glaze.     

Medieval glazed ceramic from Caesar's Forum (Rome,Italy): Production technology

This study is focused on Medieval Roman heavy lead-glazed ceramics from the archaeological site of the Caesar's Forum (Rome, Italy), dated from the 10th and not beyond the first decades of the 11th century. Optical microscopy (OM), X-ray powder diffraction (XRPD), scanning electron microscopy (SEM-EDS) and electron microprobe analysis (EMPA) have been used for the archaeometric characterization of the ceramics. Petrographic analysis of the body indicated the occurrence of three petro-fabrics, mainly composed by abundant quartz, feldspars, nodules of iron oxides, rare fragments of siliceous rocks, very rare fragments of calcareous rocks, pyroxene, biotite and olivine. This mineralogical assemblage suggests that the ceramics were fired in the range 950–1050 °C, under oxidizing conditions. SEM and EMP analysis show that the ceramic body was produced with non-or moderately calcareous clays and the heavy glaze with lead oxide, silica, alumina and alkalis. The microstructure of the glaze and the relationship with the body suggest that for the production of the ceramic repertoire of the Caesar's Forum either the single or the double firing techniques were used.     

Ascertaining the degradation state of ceramic tiles: A preliminary non-destructive step in view of conservation treatments

Conserving the cultural heritage is a general concern and the use of non-destructive techniques to characterize ancient materials is important. Serious deterioration effects in environmentally exposed ancient glazed ceramic tiles arise from the development of micro-organisms (algae/fungi) within the pore system. Subsequent biodegradation processes are particularly harmful once the decorated glaze is damaged by exfoliation/detachment.Three case studies will be addressed: Portuguese polychrome decorated tiles from the interior of two churches (16th–17th century) and from the outdoor of a Palace (18th century). Small tile fragments were directly irradiated in a wavelength-dispersive X-ray fluorescence spectrometer for glaze chemical characterization and subsequently irradiated in a powder diffractometer to assess the phase constitution of both glaze and ceramic body.Cleaning and conserving these ancient cultural artifacts involve a decontamination process applying innovative non-destructive techniques. The present work is intended as a contribution to diagnose the actual degradation state of ancient tiles in view of future decontamination actions using gamma radiation.     

Technological evolution of ceramic glazes in the renaissance: In situ analysis of tiles in the Alcazar (Seville,Spain)

The Alcazar Palace (Seville, Spain) is famous for its ceramic decorations; 16th century wall tiles of different typologies have been analyzed in order to relate the manufacturing process of their colored glazes to the evolving technologies of the Renaissance. Chemical and mineralogical compositions have been determined in situ by nondestructive X-ray fluorescence and X-ray diffraction on arista ceramics in the Cenador de Carlos Quinto, and majolica ceramics in the Palacio Gotico and the Royal oratory. The arista style belongs to the local Hispano-Moresque ceramic tradition. Majolica tiles have the complex microstructures of glazes from Italy. The two types are clearly differentiated by their typology, morphology (curved vs flat surface), and also microstructure (single vs multi-layers), glaze chemistry, and use of different coloring agents. Moreover, we found different glaze chemistries in the investigated majolicas, which correspond to different artists and/or practices.     

物理化学在陶瓷科技史研究中的应用

综述了物理化学的原理和物理化学的方法在古陶瓷科学技术研究中的应用成果,特别是在古陶瓷釉的呈色、分相釉、陶瓷釉中的气泡和坯釉过度层形成等的机理研究,并介绍了古陶瓷烧成温度和烧制年代测量的原理。随着物理化学的发展,新理论和新方法不断涌现,努力掌握这些新方法和新理论,并探索将其应用于陶瓷科学技术史研究中,将有可能出现更加显著的成果。     

Comparison of blue pigments prepared by two different methods

The color efficiency of ceramic glaze blue pigments obtained by synthesis methods was compared. the fired pigments and enameled samples were characterized by XRD, UV-vis-NIR spectroscopy, CIE-L^*a^*b^* color-measurements, and SEM. The pigments obtained by the Pechini method presented a better solubility in the molten glazes than the pigments obtained by the mechanical mixture of the oxide precursors. The pigments obtained by the Pechini method also developed a bluer color hue than the pigments obtained by the mechanical mixture of the oxide method.     

Double layers glaze analysis of the Fujian export blue-and-white porcelain from the Witte Leeuw shipwreck (1613)

Witte Leeuw was a cargo ship owned and operated by the Dutch East Indian Company. The wreck of this vessel is known for yielding a comprehensive range of Jingdezhen manufactured, blue-and-white export porcelains, particularly kraak wares; together with Fujian blue-and-white export porcelains, known as Swatow wares. A large number of ceramic fragments have been recovered from this wreck and currently reside in collections at the Rijksmuseum. For this study nine ceramic specimens were selected for further investigation, with the aim of determining the structure, composition and manufacturing process of the double-layer glazes. Both digital optical microscopy and scanning electron microscopy were used to examine the glaze morphology and microstructure; whilst energy dispersive x-ray spectroscopy was utilised to measure the spatial distribution of chemical elements and to determine bulk elemental compositions. Raman spectroscopy was also trialled, with the technique being applied to the measurement of molecular vibrations within the silicon-oxygen network and associated alkali metal oxides, with the aim of identifying potential differences in the glaze layers. Examining the ceramic specimens, the blue decorations were applied between two layers of glaze, and the majority of the blue colour extends into the outermost layer, often exhibiting dissolution in the outer layer glaze. The two layers of the glaze appear to be formulated from different compositional recipes. Some export Swatow blue-and-white wares made in the Wanli Period (1573–1620) were glazed twice and fired twice.     

喷打用蓝色陶瓷表面装饰墨水的制备与性能

制备了一种与传统陶瓷表面装饰的新技术(连续式喷墨打印法)配套的新型墨水——蓝色陶瓷表面装饰墨水。它以陶瓷颜料为基本着色料,用溶胶—凝胶法制备,以连续式喷墨打印墨水的质量标准为参照标准。经测试,所制墨水的电导率、表面张力、粘度等理化性能完全符合喷墨打印墨水的要求,适用喷墨打印法陶瓷装饰工艺的需要。研究了分散剂、粘接剂、pH值、固含量等工艺因素对该墨水性能的影响。该墨水制成时为草绿色,经煅烧,各组分反应生成颜料,显现蓝色。     

Colour in ceramic glazes: Efficiency of the Kubelka–Munk model in glazes with a black pigment and opacifier

In this study the efficiency of the Kubelka–Munk model (already known and consolidated in other industrial sectors) was evaluated in the prediction of the colour of an opaque ceramic glaze obtained by a mixture of black pigment (spinel Ni–Fe–Cr) and zircon opacifier (ZrSiO₄). Glazes with different percentages of black pigment and opacifier were prepared to determine the absorption and scattering optical constants from the reflectance curves measured with a spectrophotometer. After the physical and chemical characterization of the glaze components (frit, pigment and opacifier), suggestions for the adaptation of the Kubelka–Munk model were made to facilitate the experimental procedure of analysis. The result obtained with the adapted Kubelka–Munk model was in good agreement with the experimental reflectance curves. The reproduction of the desired colour was possible with a reduced number of experiments and the model made it possible to correlate the colour with the added pigments concentration facilitating the formulation step.     

关于釉下彩骨质瓷的研究

通过对素胎与花纸颜料中间层的研究及釉料适应性的分析与调试，研制出装饰效果高雅，铅镉溶出量为零的釉下彩骨质瓷。     

Synthesis of pigments based on the CuO-Cr2O3-Al2O3 system using the precipitation method

Compositions of ceramic pigments for coloring glaze and flux coatings have been developed using the powder method and the coprecipitation method. Comparative parameters of chromophore properties of the obtained pigments are given. The expediency of using the coprecipitation method in the synthesis of ceramic pigments is demonstrated.     

日用陶瓷釉面耐磨性增强技术的研究进展

日用陶瓷在运输和使用过程中釉面容易磨损,产生各种划痕,影响日用陶瓷的美观和使用性能。提高日用陶瓷釉面的耐磨性,对开发高品质耐磨日用陶瓷、提升我国日用陶瓷产品的品质具有重要意义。笔者分析了日用陶瓷釉面的结构特征、影响釉面耐磨性的主要的因素,探讨提高釉面耐磨性的途径和方法。     

Colour-generating mechanism of copper-red porcelain from Changsha Kiln (A.D. 7th–10th century), China

Changsha Kiln, located at Changsha in Hunan Province, south of China, is famous for exported and coloured porcelain during the Tang Dynasty (A.D. 7th-10th century) period. Although the opinion that copper-red porcelain originates from Changsha Kiln is widely accepted in academic circles, chemical characters of glaze and colour mechanism of its copper-red porcelain have not been fully investigated and studied. Therefore, a shard of opaque glaze porcelain with red pigments which excavated at Changsha Kiln (A.D. 7th-10th century) was analyzed by Energy dispersive X-ray fluorescence (EDXRF), Synchrotron X-ray absorption near-edge spectroscopy (XANES), micro X-ray diffraction (μ-XRD), microscopy and scanning electron microscopy (SEM) methods. Combining with XANES and μ-XRD results, it indicates that metal copper is the major colouring-generation element status of the red hue. On the other hand, for the first time the study demonstrates that glaze of the sample from Changsha kiln is a typical phase separated-crystalline glaze with large particles surrounding acicular crystals which lead the opaque appearances. Because the sample from Changsha Kiln is Chinese ancient early stage copper-red porcelain relic, it will help to understand the origin of copper-red porcelain in China and enrich the knowledge of Chinese ancient ceramic culture.     

On-site pXRF analysis of body,glaze and colouring agents of the tiles at the excavation site of Iznik kilns

The excavation at Iznik tiles kilns continues as the third period of the field mission. We present here the first on-site, non-invasive analyses performed with portable XRF instrument on twenty-five excavated tiles and two residue materials of the kiln. The shards studied were attributed to the productions from 14th- to 17th-centuries. The comparison was made by the discussion of characteristic elemental ratios selected from the ceramic technology criteria and PCA/Euclidean distances analysis. Three groups of body and glaze technologies were evidenced. We encountered that the amount of tin oxide in the glaze decreased over the centuries. Besides, two different types of fluxes were used in the glaze, some containing only potassium, and the others having potassium and calcium. The decors, which were investigated in this study were blue, turquoise, green, red colours, and black lines. A copper-iron mixture in the red areas was documented, which reflects the use of bornite.     

The influence of Ca2+ and Zn2+ doping on the development of sustainable pigments based on GdFeO3 perovskite: From a reddish colour towards a pure black

Black pigments are very commonly used and arouse widespread interest in the ceramic industry. Nevertheless, these pigments contain toxic elements that are detrimental to human health. In view of this, the present work is focused on the development of sustainable black pigments prepared by a coprecipitation method at 1200 °C. Samples with the nominal formula (Gd_1–xCa_x)(Fe_0.95Zn_0.05)O_2.975–x/2 (x = 0.00, 0.05, 0.10) showed single-phase orthorhombic perovskite. The presence of dopants played an important role in the reduction of Fe³⁺ to Fe²⁺ and caused different local distortions in the structure which explained the final black colouration of these pigments in comparison with the red GdFeO₃ sample. The loss of symmetry and the increase in the number of d-d transitions of iron may explain the aforementioned changes. Co-doped pigments reached low C* values, improving on the purest black colour obtained in a commercial black ceramic pigment, which contains toxic elements. In addition to presenting good NIR solar reflectance values of up to 8%, the final colours of these pigments were also stable after their application in a commercial transparent glaze at 1080 °C that could be used for tiles.     

氧化锡对仿古砖面釉发色的影响

本文以某种亚光瓷质釉面砖的面釉为基础,分别添加不同比例的二氧化锡,分析陶瓷色料在面釉中的发色情况。     

Characterization of blue CoAl2O4 nano-pigment synthesized by ultrasonic hydrothermal method

Nano-sized CoAl₂O₄ pigments, which have received significant attention as a coloring agent in glaze and bulk tile compositions, were successfully synthesized by substituting mechanical stirring during hydrothermal process with ultrasonic irradiation. Difference in physicochemical and optical properties of the CoAl₂O₄ pigments prepared by an ultrasonic-assisted-hydrothermal method was characterized using simultaneous thermo-gravimetric and differential thermal analysis (TG–DTA), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), diffuse reflectance spectroscopy, CIELAB colorimetric analysis, and testing in ceramic glazes and bodies. The ultrasonic-assisted CoAl₂O₄ pigments present a narrow particle size distribution with vivid blue color, and better thermal stability, allowing their use for ceramic inks processed at high temperature. Application of ultrasonic irradiation during the hydrothermal process produces nano-sized powders with better physicochemical and optical properties.     

On-site identification of Sceaux porcelain and faience using a portable Raman instrument

During the 18th century many European manufactures tried to imitate Chinese, Vietnamese and Japanese porcelain. To address the lack of kaolin source they had to test new processes inspired from the fritware technology. Unfortunately, the Sceaux Factory production is poor documented: it was only vaguely reported that different technologies were used to produce soft-paste and hard-paste porcelain as well as different kinds of faiences, including an undocumented “faïence japonnée”. In order to bring new information, a selection of 25 objects from the Département du Patrimoine et des Collections de la Cité de la Céramique, Sèvres, France, attributed to the 18th century Sceaux Factory production, has been analyzed with a portable 532 nm Raman spectrometer in museum reserves. Identification of the crystalline phases of the body and glaze as well as pigments allows differentiating the different technologies. According to previous studies on porcelains produced by other factories in Paris area (Chantilly, Saint-Cloud, Mennecy, Vincennes/Sèvres, etc.), wollastonite (β CaSiO₄) appears to be characteristic of soft-paste porcelain paste. Therefore, the absence of wollastonite peaks is consistent with a faience body and the concomitance with the presence of quartz peaks can correspond either to hard-paste porcelain or to faience. Cassiterite, wollastonite and quartz are identified as glaze opacifiers. Different olivine and pyrochlore compositions have been evidenced for blue and yellow pigments, respectively. This fact can be related to different pigment technologies (periods or Master).     

简述18世纪景德镇对英国瓷业的影响

18世纪末英国结合景德镇传统配方创烧出硬质骨瓷。新的硬质骨瓷在烧成范围、工艺的稳定性、釉面外观等方面大大超越了传统硬质瓷,不仅适合大规模商业生产,而且成本低廉。19世纪前叶,这种瓷器帮助英国建立起一个全新的现代瓷业,并引领英国瓷业乃至世界瓷业进入了一个新的时期。