The major elements of several Jun porcelain samples which have representative glaze colors and white thin layer of substance between the glaze and the body as well

were analyzed with EDXRF（energy dispersive X-ray fluorescence）probe technology to study the technics of ancient Jun porcelains.The result shows that the chemical composition of the thin substance is just between the glaze and the body.So it is concluded that this thin substance between the glaze and the body is a reaction layer.The CuO content of the red glaze is obviously higher than that of the blue glaze

which means that the reason why the red glaze is red is the existence of Cu.Besides CuO

the content of other elements of the red glaze is similar to that of the blue glaze

which reveals that the raw mineral of red glaze is similar to that of blue glaze.Meanwhile

it is revealed that the K2O content of reaction layer is higher than that of the glaze and the body

and this phenomenon is different from that of other oxides.K2O content of reaction layer is higher than that of the glaze and the body

which is the synthetical result of several factors

including the chemical composition of the glaze and the body

the character of silica glass of glaze

and the specialty of K2O in glass.