Development of High-fire Colored Glazes Using Waste Porcelain Powder - Focused on Reddish-Brown and Greenish-Blue Color Variations

The purpose of this study is to develop a high-fire base glaze using waste porcelain powder(WPP) to investigate its potential as a glaze raw material and to develop reddish-brown and greenish-blue colored glazes using copper oxide, iron oxide, and synthetic pigments. Commercially available white porcelain waste powder was purchased, analyzed for components (XRF), and then pretreated by wet grinding (ball milling) for 3h, 6h, and 12h to control particle size for use as a glaze raw material. Four basic Glazes were selected and iron oxide, copper oxide, and five synthetic pigments were added as coloring agents to white porcelain and celadon clay, respectively. As a result, white porcelain clay exhibited a variety of semi-gloss, transparent gloss, matte, and cracked glazes, while celadon clay exhibited an overall transparent gloss and crystalline glaze. Overall, black spots appeared irregularly and unreacted within the glaze. These are seem to be mica and iron oxide crystals remaining within the WPP. The WPP used in this experiment contained 70.24% SiO₂ and 0.54% MgO, facilitating the formation of glass. It reacted with the CaO component to precipitate subtle lime-magnesia crystals. Using WPP, we obtained stable, high-fire transparent glazes applicable to white porcelain and celadon. Among these, four basic glazes with varying WPP contents were selected and subjected to high-fire colored glaze experiments. As a result, reddis h-brown and greenish-blue colored glazes with excellent gloss and crystallinity were obtained, and the coloring tendency of iron glaze, copper glaze, and colored glazes was analyzed according to the amount of coloring agent added. This study controlled the raw material of waste ceramic powder and used it as a color glaze raw material, and this has the potential to be expanded into the basic work of architectural ceramics and sculptural ceramics in the Contemporary Ceramics. It is expected that by using ceramic waste as an alternative glaze raw material, its social value will expand into a new area called recycled ceramic materials.