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Ceramic Cup Safety Knowledge Lead and cadmium 2 |
| Ceramic Mug From:Xinxiang Ceramic Mug Manufacturers 2019-4-2 |
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From Xinxiang Ceramic Mug Manufacturer,China has always been a big producer of ceramic mugs, with a wide variety of products. From the point of view of ceramics, there are eight corresponding product standards, including daily-use ceramics, daily-use celadon, blue and white and blue-and-white exquisite ceramics, bone china ceramic mug, Jianbai ceramics, fine ceramic mug, and some traditional ceramics with local color, such as Cantonese and pink ceramics. Due to different production processes, different raw materials and decoration methods, their technical requirements are also different, but as far as standards are concerned, the main difference is that the requirements for water absorption and thermal stability are different. Fine ceramics have high water absorption, but the requirements for thermal stability are higher (200/20 C does not crack). The water absorption of other products are all below 3%, and most of the provisions are not more than 0.5. Only celadon and bone ash ceramics have low thermal stability, passing at 160/20 and 140/20, respectively. Generally speaking, under the condition of certain water absorption, products with good thermal stability have long service life. Most of the products produced in our country can meet the requirement of 180/20 C non-cracking.
If the products are classified according to the porcelain quality, they can be divided into hard and soft porcelain. Hard ceramics are mostly fired at one time at high temperature, while soft ceramics are mostly fired at low temperature. Because of different firing temperatures and different raw materials, soft ceramics have relatively more low melting point oxides. So the glaze hardness of hard porcelain is bigger than that of soft porcelain. It is not easy for knives and forks to scratch marks when used, but the glaze smoothness and brightness of soft porcelain are generally better than that of hard porcelain. The naked eye observation is softer and moist.
According to the different decoration methods of products, there are different kinds of glaze color, under-glaze color and in-glaze color ceramics. The leaching amount of lead and cadmium in ceramic products mainly comes from the glaze decorative materials on the surface of the products, such as ceramic decals and ceramic pigments for producing decals. Because these pigments generally contain a certain amount of lead, some contain cadmium, if the preparation process is not appropriate, the design of flower paper is unreasonable or the color firing conditions are not suitable, this kind of lead (cadmium) compound will be leached out of acidic food, once eaten, it will cause different degrees of harm to some organs of the human body.
Overglaze colored ceramics is a kind of product which is pasted on the glaze or directly painted on the surface of the product with the colored paper made of the overglaze ceramics pigments, and then baked at 700-850 degrees C. Because the barbecue temperature does not reach the melting temperature of the glaze, so the flower surface can not sink into the glaze, only close to the surface of the glaze. If you touch the surface of the product with your hand, you can observe the unevenness with the naked eye. Overglaze color ceramics have the quality worries of super lead.
The firing temperature of the glaze-colored ceramics reaches the melting temperature of the glaze. The ceramic pigments sink into the glaze when the glaze melts and are covered by the glaze after cooling. This product has a smooth visual surface and a glassy luster. The amount of lead (cadmium) leached out is safe because the pigments do not contact food directly.
Underglaze color is a traditional decoration method in China. All the decorations of the products are done on the ceramic body and then fired once. Like the glaze color, this kind of product has no problem of excessive lead (cadmium).
Compared with the above three kinds of decoration, most of the underglaze colors are traditional blue and blue flowers, with monotonous color and moderate price; the underglaze colors are more abundant than the underglaze colors, and the products are of higher grade, but the process requirements are strict, the cost is high and the price is high. At present, the output of the industry is not large, so the domestic market investment in the glaze colored ceramics is also small. At present, more than 80% of the products sold on the market in China are glazed ceramics, some of which have reached the high-grade level, new style, good quality and high price. They can meet the needs of the urban high-wage class and high-grade hotels, but most of them are middle and low-grade products with moderate prices and meet the needs of ordinary people's family living standards.
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