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Causes and solutions of matt glaze of porcelain cup

April 03, 2022

Bone china products, In the process of spraying glaze, it is inevitable that the glaze gloss is poor. The defects are classified as orange glaze, which is the result of glaze firing. What causes this phenomenon? What's the solution? The glaze composition is too little flux, the melting point is too high or the firing temperature is insufficient, resulting in poor crystallization of the glaze and melting of the glaze layer. The glaze layer is not uniform when the glaze is mixed. The glaze body is close to the unglazed or porous object and is absorbed by it, making the product dim locally.

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1. Because the glaze with high calcium oxide content is easy to crystallize during cooling, rapid cooling in the early stage of firing (from the porcelain forming temperature to about 750 ℃) is a powerful measure to overcome the dull glaze and improve the surface gloss.

2. Because the glaze is matte due to poor melting, the composition of glaze formula needs to be adjusted. The melting temperature of glaze with high content of silica or alumina will inevitably rise. Therefore, the glaze composition should be adjusted to make the oxide proportion appropriate and increase the melting in the glaze.

Reducing its fire resistance or appropriately increasing the firing temperature is the key to make the glaze have good properties.

3. Increase the concentration of glaze, or apply glaze several times to increase the thickness of glaze layer. When applying glaze, the glaze slurry shall be stirred evenly. Glazed objects shall be far away from unglazed or absorbent objects, and a layer of high fire retardant coating shall be applied inside and outside the sagger bottom. The glaze and stone tire must not be calcined in a sagger.

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