The production process of bone china mug is the most complicated and meticulous process. A slight neglect of any process from raw material preparation to firing may cause defects or even scrap. Blistering is one of the most common defects after the finished product is fired, and it is divided into two types: base blister and glaze blister. Among them, the base foam is divided into oxidation foam and recovery foam. The following bone china manufacturers will introduce various bubbling environments:
1. Oxidation bubbles
The foam formed by incomplete oxidation is called oxidation foam. The bubble is about the size of millet, covered with a glaze layer on the surface, which is not easy to touch with hands, and the cross section is gray, and it mostly occurs at low temperature.
2. The reason
The main reason is that the decomposed matter in the porcelain body and glaze has not been fully oxidized, and the dissipated matter has not been completely eliminated.
① The oxidation temperature is low, and the high-temperature partial oxidation air in the oxidation zone is insufficient or fluctuating.
②The preheating zone heats up quickly, the oxidation decomposition stage is short, the kiln temperature is too low at the end of oxidation, and the high and low temperature difference is too large.
③ The blank glaze contains more carbonates, sulfates and organic impurities.
④The loading density is inappropriate.
⑤ The water content of the green body kiln is too high.
3. Prevention essentials
① Properly increase the temperature of the oxidation furnace and adjust the opening of the air curtain. The proportion of wind and oil is proper. The oxidation stage is connected with strong oxidation firing.
② Shrink the height of the green body and the temperature difference between the inside and outside. During the oxidation stage, the temperature should be raised slowly or properly kept, so that the green body can be preheated and heated evenly, and the oxidation is sufficient.
③ Reduce the amount of raw materials with more carbonates, sulfates and organic impurities in the billet.
④ The loading density should be appropriate to reduce the water content of the green body into the kiln.