The reasons for the glaze peeling off of ceramic tableware

The main reasons for the glaze peeling off of ceramic tableware are as follows:

Raw material and formula issues

The difference in expansion coefficients between the body and the glaze is significant: If the hardness and softness of the body and glaze formulas are not compatible, for instance, if the body contains a large amount of quartz while the glaze contains less quartz, it will lead to inconsistent expansion coefficients between the two. When the expansion coefficient of the glaze is less than that of the body, during the cooling process, the compressive stress borne by the glaze layer exceeds the limit of the bonding strength between the body and the glaze. As a result, the glaze cannot resist the tension caused by temperature changes and thus separates and peels off in a scaly manner from the body.

Uneven mixing of raw materials: If the malleable and non-plastic raw materials in the body are not evenly mixed, and the coarse and fine particle raw materials are unevenly distributed, it will cause uneven expansion and contraction during heating and cooling, and then lead to glaze peeling. In addition, if the ball milling and material are too fine, as well as if the surface tension of the raw materials used in the formula and glaze is too high or the wettability is poor at high temperatures, it may also cause the glaze surface to peel off.

Improper glazing operation

Incomplete treatment of the body: Before glazing, if the surface of the body is too smooth, or if the accumulated dust and adhered grease are not thoroughly washed off with clean water, it will affect the adhesion of the glaze. If the glazed body is subjected to vibration or impact, the bonding force between the body and the glaze will weaken, causing peeling.

Uneven glazing: The adhesion of the glaze slurry is poor, the glaze layer is too thick, and it is prone to fall off after drying. Improper glazing operation, such as uneven thickness of the glaze layer, can also cause the glaze surface to contract unevenly during cooling, resulting in the phenomenon of glaze layer detachment and peeling.

Firing process issues

Improper sintering temperature: If the sintering temperature is too high, fusible salts will accumulate in some areas, causing the glaze to peel off due to uneven vitrification of the body. If the firing temperature is not high enough and the glaze does not melt fully, it will also affect the bonding of the body, causing the glaze surface to peel off. In addition, improper heating and cooling rates may also cause tension between the glaze and the body, leading to problems with the glassy texture of the glaze layer.

Poor environment inside the kiln: During firing, there is too much water vapor in the kiln, making the body damp. This can cause stratification between the body and the glaze, resulting in the peeling off of the glaze layer.

Usage and storage issues

Long-term wear and scratches: Even high-quality ceramic tableware may gradually show color changes at the bottom layer or directly expose the white body due to physical wear and tear on the glaze surface over a long period of time, which can lead to glaze peeling.

Environmental factors influence: Some pigments are sensitive to humidity, pH or temperature changes. When ceramic tableware is exposed to specific environments for a long time, such as the chemical effect of dishwashing liquid, alternating hot and cold, ultraviolet radiation and other conditions, the glaze surface may peel off.