In this blog post, we explore why ceramics have been cherished for so long and examine how glazing enhanced both their functionality and aesthetic value.
Ceramics are among the most common items used in our daily lives. They exist in various forms, not only as kitchenware but also as bathroom fixtures like toilets, sinks, and tiles. Furthermore, they are widely used as crafts and decorative items, establishing themselves as an important material for interior design and art. This demonstrates just how pervasive ceramics are. However, ceramics are not merely a modern invention; they are a crucial tool that has continuously evolved since humanity first began using tools. Ceramics have grown alongside the development of human culture, undergoing many changes along the way.
The history of ceramics traces back to prehistoric times. Neolithic pottery, represented by comb-patterned ware, demonstrates that humans began making necessary tools themselves as they settled into a domesticated lifestyle. Pottery from that era was widely used for storing water or food, or for performing rituals. Subsequently, as humanity entered the Bronze and Iron Ages, the technological development of pottery accelerated noticeably. By modern times, it has come to occupy an important position not only artistically but also practically. This long history of pottery does not remain confined to the past; it continues to expand its role and is steadily used in our lives today.
So, what aspects of pottery enabled its widespread use over such a long period? First, the ease of obtaining materials is a key reason. Earthen materials like clay were readily available natural resources as humans settled into a sedentary lifestyle. However, the greater reason lies in the numerous advantages brought by the glazing process. Glazing is a crucial technique that enhanced pottery’s durability, functionality, and aesthetic value, enabling it to remain by humanity’s side for millennia.
The first advantage of pottery glazing is that it provides a smooth surface. This smooth surface greatly facilitated cleaning, allowing pottery to establish itself as hygienic tableware and sanitary ware. Examining comb-pattern pottery from the prehistoric era, one can easily see its rough surface. This is because early pottery was manufactured through the simple process of ‘shaping clay – drying – firing’. However, when glaze is applied and the piece is fired again at temperatures exceeding 1200 degrees Celsius, the silica (SiO₂) and alumina (Al₂O₃) components in the glaze undergo a chemical reaction, forming a vitreous layer. This vitreous layer adheres to the surface of the pottery, providing a smooth texture. This smooth surface is not only easy to clean but also less prone to attracting contaminants, making it hygienic. This is one of the main reasons pottery became an important material for dishes and tiles in modern life.
The second advantage is that pottery does not allow water to pass through. If pottery absorbed water or leaked, it could not be used as sanitary ware or dishes. Unglazed pottery has less dense clay particles, making it prone to water leakage. However, when the surface is coated with a vitreous glaze, it eliminates any gaps for water to pass through, making it highly suitable for holding or using water. This characteristic allowed its use not only for sanitary ware like toilets and sinks but also for various water-holding vessels.
Third, glazing significantly reduces the electrical conductivity of pottery. If pottery were highly conductive, it could pose a risk of electrocution in spaces like bathrooms, surrounded by tiles and sanitary ware, potentially causing fatal accidents. However, the vitreous layer formed during the glazing process makes ceramics nearly impervious to electricity and resistant to moisture absorption, enabling its safe use as a material. This is one reason ceramics transcended their role as mere bowls or tiles to become an important material in various industrial fields.
Another advantage is that glaze plays a crucial role in determining the color of ceramics. Generally, the color of ceramics depends on the metallic components contained within the glaze. For example, Goryeo celadon uses a glaze containing iron oxide (Fe₂O₃) and undergoes a special stage called ‘reduction firing’ during the firing process to achieve its jade-like green color. During reduction firing, oxygen is removed from the kiln, eliminating the oxygen component within the iron oxide. As a result, only Fe remains in the pottery, creating the beautiful celadon blue. Joseon Dynasty white porcelain, on the other hand, uses white clay and a glaze free of metal ions to achieve its white color. Late Joseon Dynasty jinsa porcelain incorporates copper oxide (CuO) into the glaze to produce its red hue. In modern times, cobalt oxide (Co₂O₃) can be added to glazes to produce blue, chromium oxide (Cr₂O₃) for green, and a mixture of chromium and lead for yellow. These diverse colors play a crucial role in utilizing ceramics for artistic and decorative purposes.
Thus, glazing not only enhances the physical properties of ceramics but also elevates their aesthetic value. This has elevated ceramics beyond mere practical tools to recognized works of art, significantly increasing their importance. However, the development of ceramics will not stop here. Today, alongside advances in science and technology, glazing techniques for ceramics are constantly evolving. Lightweight glazes, improved durability, and the addition of self-cleaning functions will enable ceramics to be utilized in even more diverse fields in the future. In particular, increased ease of use through lightweighting could become a significant technological advancement aligned with the trends of modern society.
In conclusion, ceramics have long held a vital position in human life, and glazing techniques have further elevated their functional and aesthetic value. This progression will continue, ensuring ceramics remain steadily utilized for diverse purposes well into the future.
