Simply put, the safety of porcelain mainly depends on two points: the raw materials of porcelain and the firing of porcelain.
The raw materials of ceramics are clay (green raw material), glaze (glazed raw material) and painting (decorative raw material).
First of all, mud
The raw material of green body is generally kaolin or clay, which is basically safe because it belongs to natural clay or mineral and has no chemical addition.
Kaolin: ordinary soil, generally used for purely mechanized tea sets.
Raw kaolin: a scarce resource, make some high-end or antique tea sets.
Jade soil: high-end tea set. The feel is more oily and delicate, and the jade texture is strong.
Second, glaze
There are many kinds of glazes, but generally speaking, ceramic glazes are relatively safe. After high temperature, the glaze forms a glass-like glaze (vitrification). As long as it is formula raw ore, a small amount of chemicals can't become a climate.
High-temperature porcelain: the firing temperature is above 1200 degrees, and harmful substances are burned. Medium and low temperature porcelain: It has a high probability of containing heavy metals such as lead. Did not burn the impurities clean. Glaze is smooth, not very bright. Its advantages are high output, large output and low price.
Third, painting materials
Painting materials is more troublesome. Basically, low-cost materials are chemical materials, and colored materials contain heavy metals (lead, mercury, etc. ). So you can imagine that underglaze color is much safer.
Whether the clay glaze painting is safe depends on the firing temperature. High temperature porcelain is superior to medium temperature porcelain and low temperature porcelain. Under high temperature calcination, general harmful substances disappear or transform after oxidation and reduction of flame. Therefore, high-temperature porcelain is almost safe. If it is decorated with painting materials, underglaze color is safer than underglaze color. It is suggested that glazed utensils should only be used for decoration or fruit bowls to avoid being heated or soaked in water and oil. Medium and low temperature porcelain or some low-cost pottery are also recommended.
Safety: high temperature porcelain >; Medium temperature porcelain > low temperature porcelain; Underglaze color > underglaze color > overglaze color
Fourth, how to distinguish between high-temperature porcelain and medium-low temperature porcelain?
1, temperature
The firing temperature of high temperature porcelain is above 1200℃; The firing temperature of medium temperature porcelain is1000-1150℃; The firing temperature of low-temperature porcelain is 700-900 degrees.
Step 2 color
The color of high-temperature porcelain is fuller, more delicate and crystal clear; Medium and low temperature porcelain is dull in color.
3, feel
High temperature porcelain is smooth and delicate; Medium and low temperature porcelain is slightly rough.
Step 4 sound
High temperature porcelain is brittle; Medium and low temperature porcelain is relatively low and stuffy. (determined by density. )
5. Texture
The hardness of high temperature porcelain is relatively strong; Medium and low temperature porcelain is fragile.
6. Water absorption rate
High-temperature ceramics have low water absorption, while low-temperature ceramics have high water absorption.
7. color
Relatively speaking, high-temperature porcelain is single in color, and medium-low temperature porcelain is rich in color; Some colored porcelain, such as colored porcelain and painted porcelain, are generally fired at low temperature.
8. Thickness
Generally speaking, the embryo quality of good high-temperature porcelain is thinner than that of medium-temperature porcelain, because medium-temperature porcelain has low firing temperature, low sintering degree and looser texture than high-temperature porcelain. In order to improve the impact resistance, the fetal quality will be relatively thick.
Holding a cup of tea and savoring it, my thoughts began to drift away with the plain white jade embryo landscape blue and white porcelain in front of me. ......
Good tea is more than tea.
Drinking tea is a bad thing and a waste of time.
Tea is wonderful when it meets good utensils.
I'm Cha Xiaoyi from Jiayi Tea Set.
Only making tea sets can make drinking tea more enjoyable.