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A study on the coloring mechanism of famous ancient Chinese ceramics (Conference Presentation)
Author(s): Weidong Li

Paper Abstract

Ancient Chinese glazes are colorful and mysterious, but it has been puzzling for the researchers to illustrate the coloring mechanism of glaze scientifically and characterize glaze colors specifically. In this study, the macro-spectrum measurement system and spectral measurement specification of ancient ceramics are built up. The location and distribution of the color of the specimens of each kiln are marked on the color chart. A quantitative optical evaluation method is established for the description of the color and texture of the ancient ceramic glaze. The color and texture of ancient glaze is determined by its chemical composition and microstructure. Factors affecting glaze color include chemical factor and physical factor. Fe2+/Fe3+ ions determine the color of transparent glaze, and the body color beneath the transparent glaze also modify the visual effect of the porcelain. While the coloring mechanism of opaque and translucent glaze is more complicated. The study shows that, the mild blue colors of Jun glaze and Ru glaze mainly result from the amorphous photonic structures in the glazes, which is an important breakthrough in understanding the coloring mechanism of ancient Chinese glazes. Computer simulation of glaze structure and simulative calculation of optical properties is carried out to establish the corresponding relationship between structure and reflective spectrum. Coloring mechanism for the glazes from the same kiln site, however, is not invariable, highly related with glaze composition and firing conditions. Both ion coloring and phase-separation structure take effects in the coloration of the famous Ru glaze. Fe acts as both flux and coloring element, favors the strong immiscibility tendency between SiO2 and CaO, and precipitates from the glaze under supersaturation. The analysis reveals that ‘oil spot’ patterns of the Jian bowl of the Song Dynasty contain large quantities of highly pure epsilon-phase iron oxide. It also has a special 2D intricate microstructure with interesting optical properties, which are responsible for the remarkable silvery look of the ‘Oil spots.’ Using plant ash as the main raw material, composite decorative glazes and high-iron crystallization glazes are designed and prepared. In imitation of the droplet phase-separation structure of the ancient Qionglai and Jun glazes, a photonic structure of tightly-piled micro-balls is prepared, which provides a solid scientific basis for the physical color mechanism of the ancient ceramic glaze. The spectral database of ancient Chinese glazes can also provide important reference for the non-destructive classification and authentication of ancient ceramics from different kilns.

Paper Details

Date Published: 22 July 2019
PDF
Proc. SPIE 11058, Optics for Arts, Architecture, and Archaeology VII, 110580A (22 July 2019); doi: 10.1117/12.2525650
Show Author Affiliations
Weidong Li, Shanghai Institute of Ceramics (China)


Published in SPIE Proceedings Vol. 11058:
Optics for Arts, Architecture, and Archaeology VII
Haida Liang; Roger Groves; Piotr Targowski, Editor(s)

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