Overglaze vs. Underglaze: The Art and Safety of Tableware Selection!

Audit expert: Peng Guoqiu

Deputy Chief Physician, Fourth Medical Center, PLA General Hospital

Tableware, as an indispensable item in daily life, its safety and aesthetics have always been the focus of consumers' attention.

Among the many tablewares, ceramic tableware is loved by consumers for its unique artistic charm and practicality.

Source: The Paper

Among ceramic tableware, overglaze and underglaze are two common decorative techniques. So, is overglaze tableware safe? When buying bowls, is underglaze or overglaze better?

What is the difference between overglaze and underglaze?

Source: Baidu Encyclopedia

First of all, we need to understand the basic difference between overglaze and underglaze colors.

The underglaze coloring technique originated in the Eastern Han Dynasty. It involves painting the color material directly on the blank, sealing it with a glaze layer , and firing it at high temperature. The colors are soft and safe and hygienic. The overglaze coloring technique originated in the Northern and Southern Dynasties. The color material is painted on the surface of the porcelain , and then covered with a transparent glaze and fired. The colors are bright and varied.

Underglaze color is painted on the clay body after the blank is made, and then transparent glaze or light-colored glaze is applied and fired at a high temperature of 1200-1400 degrees Celsius; overglaze color is painted on the fired white glaze or colored porcelain, and then fired a second time at 600-900 degrees Celsius.

Source: Baidu

The two have their own characteristics in decorative effects and craftsmanship, but there are certain differences in safety.

Source: Dingxiang Life Research Institute

Overglaze tableware has bright colors, diverse patterns and high decorative value. However, since the color material is directly exposed on the surface of the tableware, if the color material is of poor quality or the firing process is improper, heavy metals may be precipitated , posing a potential threat to human health.

In particular, some unscrupulous merchants may use inferior pigments or paints to reduce costs, which may contain heavy metal elements such as lead and mercury. Long-term use of such tableware may cause these heavy metal elements to accumulate in the human body and affect human health.

Source: Dingxiang Life Research Institute

In comparison, underglaze tableware is safer. Because the color material is wrapped in a glaze seal and does not come into direct contact with food, even if the color material contains heavy metal elements, they will not easily precipitate. In addition, the color of underglaze tableware is softer , giving people a warm and jade-like feeling, which is more in line with the aesthetic concept of the Chinese people. Moreover, because underglaze tableware needs to be fired at high temperatures during the production process, its surface is smoother, less likely to breed bacteria , and more in line with hygiene requirements.

Dehua kiln hand-painted office cup works

Source: China Ceramics Headlines Official Account

However, this does not mean that overglaze tableware is useless. In terms of aesthetics and personalization, overglaze tableware undoubtedly has greater advantages. It can present colorful patterns and colors to meet people's pursuit of beauty. At the same time, with the development of science and technology, the current overglaze color process has become more and more mature, and the quality of color materials has also been greatly improved . The safety of overglaze tableware from some big brands and manufacturers has been well guaranteed.

How to choose good porcelain tableware?

1. Observe the texture of porcelain

Good porcelain tableware should have a fine and uniform texture without obvious impurities or bubbles. When choosing, you can tap the porcelain gently to hear whether the sound is crisp and pleasant, which usually means that the texture of the porcelain is relatively tight. At the same time, you can also touch the surface of the porcelain with your hands to feel its smoothness and texture. High-quality porcelain usually has a delicate touch.

2. Pay attention to the craftsmanship of porcelain

The craftsmanship of porcelain is also an important factor in measuring its quality. The patterns and colors of high-quality porcelain tableware should be clear and bright, and the lines should be smooth. In addition, you should also pay attention to the details such as the edge and bottom of the porcelain to see if they are regular and smooth, without obvious flaws or deformation.

3. Consider the safety of porcelain

When purchasing, you should try to choose regular brands and products marked "food grade". At the same time, you can also make a preliminary judgment on the safety of porcelain by observing its color. Generally speaking, porcelain with too bright or too dark colors may contain too many heavy metal elements and should be avoided as much as possible. In addition, it is best to clean and disinfect newly purchased porcelain tableware before use to ensure its hygiene and safety.

Source: Dingxiang Life Research Institute

When choosing tableware, we should weigh our needs and actual conditions and choose the product that suits us best. While enjoying delicious food, we should also pay attention to the selection and use of tableware to add more beauty and quality to our lives.