Lead glaze is a low-temperature glaze that uses the compound of lead as the basic flux and begins to melt at about 700 ° C after entering the furnace. Its main colorants are copper and iron, which are fired in an oxidizing atmosphere. Copper gives the glaze a beautiful emerald green color, and iron gives the glaze a yellowish-brown and brownish-red color. Lead glaze as early as the Shang, Zhou Dynasty has been invented, the western Han Wu Emperor period of the tombs are very few found, to the Han Xuan Emperor period, lead glaze technology began to obtain a relatively rapid development, firing successful lead glaze pottery, not only has a jadeite beautiful green, and the glaze layer is clear and transparent, the glaze gloss is strong, smooth and smooth, brilliant. However, the lead-glazed pottery found in the Han tombs is all meditative vessels, which may be related to the inability of low-temperature firing to be practical. The surface of the unearthed lead-glazed pottery sometimes has a layer of silver-white metallic luster of the substance, known as "silver glaze", which is actually a translucent coat of lead-green glaze, which is a layer of sediment. When the lead green glaze is in a humid environment, due to the action of water and atmosphere, the glaze is slightly dissolved, and the dissolved substances together with the original soluble salts in the water precipitate on the surface and cracks of the glaze layer under certain conditions. However, the contact between this layer of sediment and the glaze is not very tight, so the moisture can still enter the gap between the sediment and the glaze, and continue to dissolve the glaze, resulting in new sediments. So repeatedly, when the sediment reaches a certain thickness, due to the interference of light, a silvery-white luster is produced. This silver glaze is sometimes found on Han Dynasty green glaze pottery and Tang Sancai. This silver glaze is produced due to the fact that the patina glaze is susceptible to the dissolution of water and atmosphere. Iron yellow glaze and cobalt blue glaze are not susceptible to water dissolution, and the surface does not produce "silver glaze". Lead glaze refractive index is relatively high, high temperature viscosity is small, fluidity is larger, melting temperature range is wider, melting is stronger, so it avoids the more common "orange peel" and "pinhole" in lime glaze and lime alkali glaze. At the same time, there are no bubbles in the glaze layer and the presence of a large number of residual crystals, making the glaze layer clear and transparent, the surface is smooth and smooth, and it is full of decorative feeling. Lead-glazed pottery was still fired in the north during the Three Kingdoms and the Two Jin Dynasties, but the quantity was small and the quality was not as good as before. Lead-glazed pottery in the Northern Dynasty was mature in craftsmanship and varied in variety, and firing was made in various regions of the North. The Northern Wei Dynasty was popular for making utensils and palace building components with low-temperature lead glaze, and the glaze color was bright and lustrous, some adding green color to the yellow glaze and white glaze, and some yellow, green and brown colors were used at the same time. The appearance of multi-colored glazes laid the foundation for the brilliant and colorful Tang Sancai pottery. The Northern Dynasty lead glaze products are more refined, such as the yellow glaze high foot plate found in the Fengshi Tomb Group in Hebei Province, and the glaze is yellow and shining blue, crystal like a mirror. The most representative ones, such as the yellow glazed flat pot excavated from the tomb of Northern Qi Fan Chu in Anyang, Henan, have a dark yellow glaze, lustrous and transparent, exquisitely made, and have been mistaken for porcelain. Unearthed glazed pottery such as green glaze, light yellow glaze and sauce color glaze, some of which add deep yellow glaze and green color to the light yellow glaze at the same time, can be described as the predecessor of Tang Sancai pottery, which plays the role of inheriting the past and opening up the future between Han and Tang. During the Ming and Qing dynasties, susancai, low-temperature yellow glaze and glass glaze all belonged to lead glaze, but the firing temperature was different.
Copper red glaze is a red glaze made by reducing the flame with copper-containing substances as colorants. It is reported that the earliest copper red glazed porcelain in China appeared in the Changsha kiln in Hunan in the Tang Dynasty. But at that time, the copper red glaze hair color was dark and dull. The copper red glazed porcelain, pure vermilion, was successfully fired in Jingdezhen in the Yuan Dynasty, and its pure and stable red glaze color is still breathtaking. By the beginning of the Ming Dynasty, during the Yongxuan era, Jingdezhen created a ruby red (also known as "Ji Hong" and "Sacrifice Red"). However, in terms of the conditions at that time, the red-glazed porcelain fired in Jingdezhen can be regarded as "a thousand kilns and one red", and there are rumors that there are ten kilns and nine cannot be produced. In the middle of the Ming Dynasty, the copper red glaze was once lost, and it was changed to alum red. The Qing Kangxi Dynasty was restored, firing into lang kiln red, cowpea red and other precious varieties, "Museum Requisition: (15167) (306566)" copper red glazed porcelain was also greatly improved in the Kangxi period, it seems that the heavens for the red glaze porcelain care is over, and the later generations of copper red glazed porcelain have never surpassed Kangxi red. Red glazed porcelain is made with copper oxide as a colorant, and its firing is very difficult. At the time of firing, the kiln position where the product is placed, the temperature and atmosphere in the kiln, and even the seasonal changes in the weather outside the kiln have a great impact on its firing. The reason why copper can turn into a beautiful red color in a high temperature reduction atmosphere. Theoretically, with copper oxide as a color agent, calcined in a stable reducing flame, you can get a bright red, although with the appropriate reduction flame firing, you can get a beautiful red, but as long as there is a slight deviation, or the reduction is not complete, or partial oxidation, or low temperature and other factors, may lead to red glaze color discoloration, gray, green, black, or burn out and other phenomena. Therefore, red glazed porcelain is extremely rare and cherished by the world.