Analysis of the Glaze Surface Technique of Ceramic Tableware

The glaze techniques of ceramic tableware mainly include underglaze painting, mid-glaze painting and overglaze painting. Each of them has its own characteristics in terms of craftsmanship, safety and color expression. The following is a specific analysis:

Underglaze painting

The underglaze painting technique involves first painting patterns on a plain body, then covering it with transparent glaze and firing it. The colored materials are placed beneath the glaze layer. The firing temperature is usually around 1200℃ to 1300℃. The high-temperature firing results in a high melting point of the glaze surface, and the pigments are sealed beneath the glaze layer, isolated from the external environment, making them less prone to wear and erosion. It has high safety. Under the fully enclosed glaze surface, it will not come into direct contact with the pigment during use. As long as the glaze surface is intact, the risk of lead leaching is very low, and there will be no excessive heavy metals. It is very safe to use as daily tableware. The patterns of underglaze painting never fade, but the process is complex and requires meticulous operations such as painting on the body, which demands higher skills from the painter. Generally, its price is higher than that of ordinary ceramics or overglaze painted ceramic products. Moreover, some special pigments may change during the high-temperature firing process, affecting the color expression effect.

Mid-glaze color

Underglaze painting combines the advantages of underglaze painting and overglaze painting and is produced through two high-temperature firing processes. The production process involves first applying glaze at high temperature, then painting and coloring, and finally applying another layer of glaze at high temperature, with the colored material located between the two layers of glaze surface. The firing temperature is around 1250℃ to 1340℃. At high temperatures, pigment particles seep into the glaze. When it cools down, the glaze surface seals, solving the problem of "lead poisoning" in ceramics. The colors of the glaze mid-color are bright and vivid, smooth to the touch, with a smooth and flat surface and vivid hues. It has strong decorative and artistic appeal. After being fired at high temperatures twice, it has high wear resistance and corrosion resistance, and is also very safe. It is suitable for making daily necessities such as tableware and tea sets, as well as various artistic porcelain, meeting the needs of different occasions and people. However, the in-glaze painting technique is the most complex and demands high painting skills. Since the colored materials present their effects within the glaze layer, it requires a high level of skill from the painter. One needs to possess proficient painting skills and rich experience to accurately draw exquisite patterns on the glaze surface. At present, porcelain made with the in-glaze painting technique is relatively rare in the market and is expensive to produce. It often becomes an artistic treasure at major auctions.

Overglaze painting

Overglaze painting is a process of decorating the glaze surface with colored materials. It begins with glazing at high temperatures, followed by painting and coloring, and then firing at low temperatures, typically between 600℃ and 900℃. As the colored materials are on the glaze surface, without the protection of the glaze, they are prone to corrosion and fading, and the patterns and textures can be felt by hand. Its advantages are that the baking temperature is low, the color development of the colored materials is stable, the tones are relatively bright and rich, and it will not volatilize (or react) to change color due to baking. However, the drawbacks are also quite obvious. The adhesion between the colored materials and the glaze surface is not strong, it is prone to mechanical wear and tear, and is susceptible to acid and alkali corrosion. It is not as durable as underglaze and mid-glaze. If low-temperature processes and inferior colorants are used for coloring, there is a risk of corrosion by acidic or alkaline substances or the precipitation of heavy metal components at high temperatures. The color will fade over a long period of use, which is not very safe. However, overglaze porcelain that has passed inspection can also be safely in contact with food.