The Chemical Composition And Painting Techniques Of Cobalt Pigment Applied On Tang Sancai Wares Excavated From Shaanxi And Henan

The Tang Sancai ware was the first production which decorated by cobalt blue for pattern in the C hinese ceramic family.It laid the foundation for the emergence and prosper ity of the blue-and-white porcelain.The reports of 1424 Tang tombs were collected and analysed and it indicated that there were 144 Tang tombs with some Tang Sancai wares in China.Among these tombs,43 tombs unearthed 171 blue wares.Almost of these blue wares were found in Shaanxi and Henan province.Two capital cities,Chang’an(Xi’an)and Luo’yang,were located in the two provinces in Tang Dynasty.According to collection and analysis about blue wares,royal family and officer did not monopolize the blue wares and many ordinary people used many delicate blue wares.In terms of configuration,the figures were more popular in Shaanxi than in Henan and the largest proportion of blue wares in Henan was utensils.The blue pigment applied on blue wares may co ntain C u,Fe,N i,Mn,Zn and Ba.Besides,the cobalt pigment used on Tang blue-and-white porcelain contained C u.It indicated that Tangsancai wares and Tang blue-and-white porcelain may use similar cobalt mineral.The results of chemical composition tests showed that the “blue pigment” was a kind of blue glaze rather than pigment.This glaze was similar with white glaze applied on Tang Sancai wares,and these glaze could fuse with each other.In the beginning,blue decoration and other colours decorated wares together and they had the same role in decoration.However,blue decoration became more and more important,which was relieved against white or yellow glaze.This style was similar with blue-and-white porcelain.O n the basis,two models of painting technique were proposed—monolayer and double-layer.Potters used white lead glaze to cover a ware in the first step and then,used cobalt pigment on the glaze.Compared with blue-and-white porcelain,the double-layer model also had two layers.This character was similar with that of the blue-and-white porcelain.In summary,the changes of decoration style and painting technique contain some meaningful information about the development of cobalt pigment,which is one of the key points in studying the emergence of Tang blue-and-white porcelain.