Messi Biology states that in the kiln-fire tempering of ceramic production, there is a low-profile yet critical raw material—Magnesium Oxide (MgO). Although this seemingly ordinary alkaline oxide is added to glaze formulas in amounts of only 1% to 5%, it comprehensively enhances the texture, performance, and artistic expression of ceramics through subtle chemical interactions, acting as an indispensable “magic additive” in the ceramic industry.
Optimizing Melting Characteristics
The core function of magnesium oxide is to optimize the melting properties of the glaze. As a unique “high-temperature flux,” it does not melt directly at low temperatures. Instead, it lowers the high-temperature viscosity of the glaze by breaking down the silicate network structure. This allows the glaze to flow uniformly at high temperatures of 1250–1350°C, fully filling the pores of the ceramic body to form a smooth and dense glaze layer. This characteristic not only reduces the firing temperature by 50–100°C—lowering energy consumption and the risk of deformation—but also prevents defects such as pinholes and glaze crawling, significantly improving the yield rate. In low-temperature fast-firing processes, the rapid melting capability of magnesium-containing glazes greatly enhances production efficiency.
Strengthening Performance as a “Protection Expert”
In terms of performance reinforcement, magnesium oxide acts as a “protection expert.” It reacts with silicon and aluminum ions in the glaze to form high-strength microcrystalline phases such as forsterite and spinel. These microcrystals act as a “rigid skeleton,” allowing the glaze layer to reach a microhardness of up to 5.26 GPa and a Mohs hardness of over level 7, effectively resisting daily wear and tear. More importantly, magnesium oxide adjusts the coefficient of thermal expansion of the glaze to align with the ceramic body. Acting like a “buffer,” it relieves internal stress during cooling, fundamentally reducing glaze cracking and peeling—a factor particularly vital for large-scale ceramics and thick-walled pieces. Meanwhile, the stable magnesium silicate structure enhances the glaze’s resistance to acids and alkalis, extending the service life of the ceramics.
Aesthetic and Functional Expansion
Magnesium oxide demonstrates incredible flexibility in aesthetics and functional expansion. Added in appropriate amounts, it increases the refractive index of the glaze, giving transparent glazes a crystal-clear luster. By controlling the dosage, it can promote the precipitation of microcrystals to create a soft matte or opacified effect with a silk-smooth touch. In colored glazes, it fixes coloring ions, making the cobalt blue of blue-and-white porcelain and the celadon green more pure and stable, while suppressing color interference caused by impurities. In artistic ceramics, precise control of MgO content and firing systems can cause the precipitation of needle-like or plate-like crystals, forming naturally vivid crystalline textures or working synergistically with other oxides to produce iridescent effects, providing infinite possibilities for creation.
Green and Sustainable Development
Today, magnesium oxide has become a core raw material for eco-friendly ceramics. It can replace traditional lead-containing fluxes to produce daily-use ceramics that meet food safety standards. Its waste materials can also be recycled, aligning with the concept of sustainable development. From the wear and frost resistance of architectural tiles to the warmth and translucency of daily-use porcelain, and the unique textures of artistic ceramics, magnesium oxide interprets the industrial wisdom of “achieving great results with small efforts,” continuously driving the ceramic industry toward a dual upgrade in performance and aesthetics.