What do you know about ceramic glazes?

At present, the ceramic ware circulating in the market can be divided into overglaze color, glaze color, underglaze color, color glazed porcelain and some uncolored white porcelain and other varieties. Due to the different ways in which ceramic tableware is decorated, the possible health effects are also different. Among them, the lead and cadmium content in the glaze color, underglaze color and most of the color glazed porcelain and white porcelain are very low.

However, if the amount of pigments containing lead and cadmium is too large during processing, or the temperature and ventilation conditions are not enough during roasting, it is easy to cause the dissolution of lead and cadmium to exceed the standard. There is another kind of bone ash porcelain is white, its porcelain is transparent, the glaze is smooth and smooth, and it is deeply loved by consumers. However, the production of this kind of porcelain is difficult, and most of them use high-temperature plain firing and low-temperature glaze firing techniques.

The glaze is a low-temperature lead-containing glaze, and if the production process is not properly controlled, there is a high possibility that the lead dissolution amount will exceed the standard. In order to avoid the possible adverse effects on health of tableware, experts remind that people should try to choose products with less decorative patterns and bright patterns on the inner walls of glaze and underglaze colored ceramic utensils and tableware. Don't buy cutlery that can be wiped off by hand.

For unsafe products, you can soak them in vinegar for a few hours, and if you find that there is a significant change in color, you should discard them. To identify the quality of ceramic tableware, as follows: hold the ceramic in your hand and observe.

Good ceramic color is a natural milky white unique to natural bone powder, observe the permeability of ceramics against the bright light, see whether the composition of the cup is meticulous or not, good ceramics should have better light transmission and uniform without impurities, feel the delicacy and hardness of porcelain by hand. The addition of beef bone meal makes the weight of ceramics lighter than other porcelain, which can be thinner than ordinary porcelain, and the quality is light, fine and hard (twice that of daily porcelain), and it is not easy to break. With a flick of the index finger and thumb, you can hear a crisp sound of ceramic "ding".

If you rub your hand in water on the mouth of the bowl, it will make a sound similar to that of an airplane flying by, of course, the sound is relatively small, so you should listen carefully.

Toxic and non-toxic mainly from two aspects, one is ceramic raw materials, and the other is firing. Ceramic raw materials are mainly raw materials (mud), glaze raw materials (glaze), and decorative raw materials (painting materials). Generally speaking, the mud of the green body is porcelain clay (mainly kaolin) or clay, which is basically safe, because there is generally no chemical additive, it is natural clay or minerals, and only the difference in grade quality.

The problem is mainly with the glaze or paint. After high temperature, the glaze forms a glaze (vitrification) with similar glass properties, as long as it is the formula raw ore, a small amount of chemical industry can not become a climate. Painting materials are more troublesome, basically now low-cost are chemical materials, color materials contain heavy metals (lead, mercury, etc.).

Therefore, it is conceivable that underglaze color is relatively safe. The second firing problem, whether the mud glaze painting material is safe, but also depends on the firing temperature, high-temperature porcelain is better than medium and low temperature. High temperature is generally referred to as 1280 degrees Celsius to 1350 degrees Celsius.

Under such a temperature calcination, after oxidation and reduction atmosphere, the general harmful substances disappear or transform. To sum up, high-temperature porcelain can almost be considered safe, and if there is a paint decoration, then the underglaze is safer than the overglaze. It is recommended to only decorate or arrange fruits on the glaze, and avoid being heated or soaked in water and oil.

Medium-temperature porcelain or some low-cost pottery is also used. Therefore, buy porcelain on ** and avoid buying some rare and cheap hand-painted patterns of foreign trade medium temperature porcelain. The easiest way to distinguish between high-temperature porcelain and medium-temperature porcelain is to look at the color, see the thickness and listen to the sound.

First of all, the color can be judged by more than 6 percent of medium temperature porcelain. The glazed vitrification layer of medium-temperature porcelain is relatively thin, only a shallow layer of refraction, and even the tire color can be seen directly, the glaze and painting material used for medium-temperature painting are different from the formula and high temperature, and the effect is similar to gouache painting, generally speaking, the painting is rougher, which is not only on the process, but also depends on the fetal quality and pigment characteristics.

Looking at the thickness, generally speaking, a good high-temperature porcelain fetal quality will be thinner than medium-temperature porcelain, because the medium-temperature porcelain firing temperature is low, the degree of sintering is not high, and the texture is higher and the temperature porcelain is loose, in order to improve the impact resistance, so the fetal quality will be relatively thicker. Listening to the sound is more dependent on experience, flicking the utensils with your hands, the sound of high-temperature porcelain is clearer and closer to the metal sound, listening to the sound has a sense of denseness, while the sound of medium-temperature porcelain is more muffled, which is due to the density.

Common glazes such as feldspar glaze, lime glaze, talc glaze and other common glazes do not contain harmful substances in the glazing process, so they are usually prepared into raw glaze for glazing processing. Glazes such as lead glaze, boron glaze, lead boron glaze and other glazes often come into contact with lead, aluminum and other harmful substances in the glazing process, if the raw glaze is used, it will cause health hazards to the operator during the glazing process, so it is necessary to prepare the frit glaze first. Because the glaze preparation frit glaze will chemically modify harmful substances such as lead and aluminum, so that its harm to the human body is greatly reduced to a safe level.

But in general, whether there is harm depends on the specific composition of the glaze. In addition, some lead-glazed finished ceramics will also produce lead pollution to a greater or lesser extent during daily use, so it is recommended that such products be kept away from infants and young children.

Quartz, feldspar, and clay are used as raw materials.

Glaze is a silicate.

The glaze applied on ceramics is generally made of quartz, feldspar and clay as raw materials, which are ground and mixed with water, and then coated on the surface of the green body and roasted at a certain temperature.

And when melting, the temperature drops, forming a thin layer of vitreous on the surface of the ceramic.

It enables ceramics to increase mechanical strength, thermal stability, dielectric strength and prevent the erosion of liquids and gases. The glaze also has the effect of increasing the beauty of porcelain and making it easy to wash and wipe, and not being stained by dust.

Key features:

The maturation temperature of the glaze is slightly lower than the firing temperature of the billet, so that the melt of the glaze is evenly spread on the billet and the billet tire does not produce deformation, and the glaze is required to have a molten state of not less than 30 temperature ranges.

to eliminate defects such as glaze bubbles and pinholes.

The coefficient of expansion of the glaze.

It is slightly lower than the expansion coefficient of the billet, so that the glaze is completely attached to the blank during firing, and after cooling, the glaze layer is in a state of stress due to the volume effect, so as to improve the tensile strength and thermal stability of the product.

Ceramic glaze is made of clay, feldspar, and quartz materials.

Ceramic glaze is made of clay, feldspar and quartz as raw materials, and is prepared by adding water and grinding according to the proportion, and is generally coated on the surface of the green body to fire ceramics. Ceramic glaze can prevent the erosion of liquids and gases, and can also increase the aesthetics of ceramics to a certain extent, and is also easy to maintain and maintain the luster of the ceramic surface.

The glazing process is a kind of ancient ceramic production technology, which refers to the application of glaze paste on the surface of the molded ceramic body. The main function of glazing is to protect the green body, make the surface of the product smooth, impermeable, non-polluting, and improve the mechanical strength, surface hardness, chemical stability and thermal stability of ceramic products.

The glaze can hide the defects of the green body and greatly improve the decorative effect of ceramic products. The glaze layer can prevent the dissolution of toxic elements in the color material, and can increase the function of the product, such as sterilization, anti-static, luminescence and other functions.

The glaze is truly uncoated, wear-resistant and not easy to scratch, superior resistance to chemical erosion, safe, healthy and long-lasting. The ceramics we use daily are generally dressed in a smooth and smooth dress, and this kind of ceramic clothing is called "glaze".

There are several types of ceramic glazes

1. Raw material glaze, which is made by grinding materials that have not been melted, usually we can divide it into feldspar glaze and lime glaze. Feldspar glaze has high hardness, excellent luster, milky white color, but the expansion coefficient is very large, and it is easy to crack. The hardness of lime glaze is also very large, and the luster is also good, and the transparency is very high, but the melting range is not large, so it is easy to cause smoke when firing, and it is mostly used in decorative products.

2. Frit glaze is made by mixing various materials and inorganic raw materials in corresponding proportions, and then melting and grinding at high temperature. When fine grinding, it can be mixed with a small amount of plastic clay, and the glaze slurry produced is relatively stable and has excellent adhesion. It is characterized by a very smooth surface of the glaze, and few pinholes, mostly used in soft porcelain products, such as bone china, talc porcelain and glazed tiles.

3. Molten salt glaze, which is characterized by a relatively light and thin glaze layer, but very hardness, usually closely combined with the embryo body, and good acid and alkali resistance, first-class thermal stability, most of which are used in chemical ceramic products.

4. Clay glaze, we usually call it mud glaze, it is made of pure natural clay after washing, its color is between yellow-brown and black-brown, which is characterized by being very simple to make, and saves a lot of costs, most of which are used in ceramic products.

Kiss! Hello, happy to answer your <>

How to distinguish between ceramic glaze and ceramic glaze is as follows: 1. Different raw materials: the ceramic glaze liner is mixed with mineral raw materials and chemical raw materials according to the ratio and finely ground into a slurry liquid applied to the surface of the green body, which is calcined at high temperature.

The ceramic liner is an inorganic material that is rich in natural iron and zinc and calcium, which are beneficial to human health. 2. Different degrees of smoothness: the ceramic glaze is artificially processed, and the inner liner is smooth.

The ceramic inner tank is natural, and the inner wheel is not very smooth. 3. Different performance: ceramic glaze can be uncoated, homogeneous with the inner tank, and wear-resistant and not easy to scratch.

The ceramic liner is a non-stick coating, which is non-stick for a short time and will slowly come off with time and temperature. I hope I can help you <>

Do you have any other questions?

Dear, hello, I am happy to answer for you, what is the role of glaze in ceramic productsA: In ceramic products, glaze is a colorless or colored vitreous thin layer covering the surface of ceramic products, which is made of mineral raw materials (feldspar, quartz, talc, kaolin, etc.) and raw materials in a certain proportion (some raw materials can be made into frit first) after grinding to make glaze slurry, applied to the surface of the body, calcined at a certain temperature1. Enhance the strength of ceramics, glaze to increase the mechanical strength, thermal stability, electrical strength and prevent the erosion of liquids and gases

2. Dust-proof effect, glaze has the effect of beautifying utensils, making ceramics easy to wash, not being stained by dust, etc., and the glaze can also be decorated with various decorations to enhance the artistic effect of products3. Extend the service life of ceramics, and the glaze will not be eroded by dust and filth. There are many types of glaze, according to the type of body, there are porcelain glaze, pottery glaze and flint glaze; According to the firing temperature, it can be divided into high-temperature glaze and low-temperature glaze; According to the appearance characteristics, it can be divided into transparent glaze, opalescent glaze, color glaze, glossy glaze, matte glaze, crack glaze (open piece), crystalline glaze, etc.; According to the glaze composition, it can be divided into lime glaze, feldspar glaze, lead glaze, lead-free glaze, boron glaze, lead boron glaze, etc.

1. Tang Sancai, popular in Tang, is coated with white, green, brown and yellow glaze on the carcass of vegetarian burning, and baked at 1100 degrees kiln temperature. At that time, it was mostly used as funeral goods; 2. Glaze color, painted on the fired plain vessel, and then baked at low temperature, because the color is attached to the glaze, hence the name. It was first seen in the Song Dynasty; 3. Underglaze color, painted on the green billet, and then glazed high hole rolling temperature firing, color pattern under the glaze, never fall off.

4. Red in the glaze, painted on the tire with copper oxide as the color agent, and safflower on a white background was fired at high temperature after glazing, which began in Jingdezhen in the Yuan Dynasty; 5. Doucai, on the body with blue and white to outline the outline of the pattern, glazed into ceramics, filled with a variety of colors in the contour line, and then fired by a low temperature furnace fire, the picture presents the underglaze blue and white and glaze color than the beauty of the fight, hence the name. Started in the Chenghua period of the Ming Tourism Hall; 6. Open piece, both ice cracks, glaze cracks and ice cracks. Due to the different expansion coefficients of the glaze, the kiln is produced by cold air prematurely, which is the main feature of the Song Dynasty kiln; 7. Blue and white, one of the varieties of underglaze color, with cobalt oxide as the color agent, painted on the blank tire, covered with transparent glaze, fired at a high temperature of 1280-1320 degrees, blue and white, the main porcelain of the Ming and Qing dynasties; 8. Glaze in color:

It is decorated on the porcelain with a good glaze, and then fired at a high temperature, and the color material or glaze melts into the previous dismantling and firing glaze, which seems to be in the middle, which is similar to the glaze color process, but it is different from the glaze color.