Made of blue underglaze and enamelled ceramic , porcelain .

由蓝色釉下陶瓷和搪瓷，瓷器。

Engrave the veins of the underglaze red flowers with an engraving needle .

用刻针将釉里红花形刻出脉纹。

At jingdezhen pigment with a very low-grade cobalt content and high in iron impurities was applied to porcelains beneath the glaze and can be hard to distinguish from underglaze iron painting ( see cat . No. 1:23 ) .

钴含量极低、铁杂质浓度很高的景德镇颜料适用于瓷器的底釉，并且很难同釉下铁绘画进行区分（见目录1:23）。