What is Glaze (Chinese Colored Glaze)
Glaze, known as "Liuli" in Chinese, is a precious traditional Chinese craft and a unique cultural symbol with a history of thousands of years. For a long time, there was much debate about its accurate English translation until it was officially designated as "glaze" by the Zibo Ceramics, Glaze and Textile Industry Development Center in 2020, putting an end to the controversy. Different from ordinary glass, glaze carries profound cultural connotations and exquisite craftsmanship, and is hailed as the first of China’s five famous artifacts, alongside gold and silver, jade, ceramics, and bronze.
In terms of material composition, glaze is a translucent, colored glassy substance made from quartz sand, feldspar, borax, and other main raw materials, which are fired at high temperatures. Although it has a similar chemical composition to glass, it is fundamentally different from ordinary glass (English: glass) in terms of production technology, appearance characteristics, and cultural connotation. As recorded in relevant research, the calcium-sodium ratio (CaO/Na₂O) of ancient Chinese glaze is generally lower than 1:2, a unique formula that endows it with both hardness and light transmittance, presenting a gem-like luster and iridescent effect.
The history of Chinese glaze can be traced back to the Western Zhou Dynasty. Early glaze production originated from by-products of bronze smelting and the practice of firing primitive porcelain. During the Spring and Autumn Period, real glazed artifacts began to appear; for example, light blue glaze inlays were found on the Sword of Goujian unearthed from the Chu Tomb No.1 in Wangshan, Jiangling, Hubei. By the Yuan Dynasty, the production of glaze in Boshan, Zibo, Shandong Province had formed a certain scale, and Boshan gradually became synonymous with Chinese glaze. In the Ming and Qing Dynasties, glaze production reached its peak, with imperial kilns set up to produce tributes for the royal family, and glazed products became a symbol of status among the nobility.
Boshan, known as "China’s Hometown of Glaze", has a unique and long-standing glaze-making history. The Boshan glaze firing technique was included in the national intangible cultural heritage list in 2008, reflecting the inheritance and value of this traditional craft. The production process of glaze is extremely complex and mostly hand-made, with more than a dozen processes. Taking the lost-wax casting method (Pate-de-verre) as an example, it needs to go through designing prototypes, making silicone molds, pouring wax, refining wax models, firing in kilns, polishing, and other steps. Each step requires exquisite craftsmanship, and any mistake may lead to the cracking of the work or the generation of irregular bubbles.
In terms of cultural connotation, glaze has rich symbolic meanings. In Buddhism, it is listed as the first of the seven treasures, symbolizing a pure and spiritual state of mind, and is believed to have the meaning of warding off diseases and evil spirits. In ancient Chinese culture, it was regarded as more precious than jade because of its rarity, and was often used to metaphorize pure and flawless things, such as the description of "a glaze world with white snow and red plums" in A Dream of Red Mansions. At the same time, the fragility of glaze also implies that beautiful things are easy to pass, conveying the ancient Chinese philosophy of cherishing the present.
It is worth noting that the English translation of glaze has a clear standard: "glaze" is the officially recognized term, while "colored glaze" is also a common expression in daily and foreign trade contexts, which can clearly distinguish it from ordinary glass. The Encyclopedia Britannica also uses "glaze" when introducing Boshan glaze, recognizing its uniqueness different from ordinary glass. Today, with the inheritance and innovation of craftsmen, Boshan glaze has developed a variety of products, including ornaments, daily necessities, and artworks, which are not only popular in China but also exported to all parts of the world, becoming a window to show Chinese traditional culture to the world.
In short, glaze is not only a kind of handcrafted art with exquisite craftsmanship but also a carrier of Chinese history and culture. It has witnessed the wisdom of ancient Chinese craftsmen through thousands of years of inheritance and development, and still shines with unique charm in the modern era, interpreting the beauty of traditional Chinese culture in a translucent and colorful way.