Beauty of science: microstructure of blue decor of Qinghua porcelain

20-08-2015

The image shows a trichromatic map (Co, Mn and Ca) of fragments of Qinghua porcelain from the Ming dynasty (1279-1368 AD). Quinghua porcelain presents characteristic blue decoration, made from a cobalt pigment, over a white background.

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This image originates from a Chinese-French collaborative project between Sun Yat-sen University (Guangzhou), CEMES-CNRS (Toulouse) and the ESRF (PHC XU GUANGQI n°34389UD). The aim is to study the manufacturing processes and in particular to understand the chromogenic mechanisms of blue decors.

Micro-X-ray fluorescence maps were recorded at beamline ID21. Two fragments of porcelain were glued face to face (the glue is in the black part in the centre of the image below) before being prepared as a thin cross-section. Circular shapes in the image correspond to air bubbles within the glaze. The analysis reveals elemental composition over the full stratigraphy. The internal part of the glaze (pigment zone, appearing yellow in the figure) contains some cobalt-based pigments as well as Ca-rich needle crystals. These crystals are absent in the upper glaze, which shows much lower concentration of Co and Mn. By comparing different samples of different colours (tint and intensity), links between the chemical composition and colour can be established.

Micro-X-ray fluorescence map of Qinghua porcelain

Micro-X-ray fluorescence map of Qinghua porcelain. Image credit: P. Sciau, T. Wang (CEMES-CNRS), T.Q. Zhu (Sun Yat-sen University, Guangzhou), E. Pouyet, M. Cotte (ESRF).

 

Chinese Ming dynasty porcelain  

An example of Chinese Ming dynasty porcelain: Blue and white vase (1271-1368), Jingdezhen, unearthed in Jiangxi Province (Credit: World Imaging, CC BY-SA 3.0).

 

Top image: Microstructure of blue decor of Qinghua porcelain (Chinese Ming dynasty).