Five-colored ceramic under Glair was created by Liling, which maintains the characteristics of hand-made and needs to go through 10 major steps such as material selection, mud making, clay-shaping, slip casting, unglazed firing, painting, glazing, calcination at high temperature, shaped surface-cleaning with mould and roasting and more than 60 processes can only be used.
■ Material selection: including mud-selection and glaze-selection. The viscosity of porcelain clay is required to be more viscous, whiter in color, and less in iron and other impurities. The five-colored porcelain underglaze is a kind of high temperature porcelain, which requires high temperature resistance of the glaze and with basic glaze of feldspar and quartz. The glaze formula is different based on different performance colors.
■ Mud making: The process of making mud is fine and paid attention to removing iron and removing impurities. The porcelain mud produced by the water bucket (mortar) through crushing is not easily deformed during the firing process, and is superior to crushing mud with the ball crusher.
■ Clay-shaping：The forming method of the five-colored porcelain under glaze mainly has two methods of Clay-shaping and slip casting. Clay-shaping is an ancient technique in which the plastic body is manually drawn into a variety of shapes on a rotating wheel.
■ Casting: using the water-absorbing physical properties of porous gypsum mold, the ceramic powder is formulated into a fluid mud and injected it into the porous mold (mainly are plaster molds). The moisture is absorbed by the mold (gypsum) to form uniform mud layer with a certain thickness and body with a certain strength after dewatering and drying.
■ Unglazed firing：The ceramic green body is heat-treated at a temperature within 800 ℃ to 900℃ to impart a certain mechanical strength to the green body.
■ Painting: draw the colorful pattern or picture with ceramic paint on a ceramic green body after unglazed-firing. Most of the five-colored art porcelains under glazed in LIling use the technique of double-drawing Fenshui to paint ceramic pigments on green body of ceramic.
■ Glazing: The glaze is applied to the ceramic body. The glaze is made by raw materials (feldspar, quartz, talc, kaolin, etc.) of grinding minerals and chemical raw materials in a certain proportion. It can be vitrified after being calcined at a suitable temperature to make and the mechanical strength, thermal stability and dielectric strength of the product can be on an increase. It can also beautify the utensils, easy to wipe, and not easily eroded by dust and impurities.
■ High-temperature calcination: After painting and glazing, the porcelain billet is placed in a kiln for high-temperature calcination, and the temperature of calcination is generally controlled at 1380℃ - 1400℃. The fuel used in the Liling kiln has experienced three stages: solid fuel (wood, coal), liquid fuel (oil) and gaseous fuel (natural gas). Gas fuels are now basically used, which make the temperature more controllable and less environmentally polluting.
■ Shaped surface-cleaning：The five-colored porcelain under glaze calcined under high-temperature is shaped according to the condition out of kiln by using a grinding machine, diamond, gauze, hand hammer, brush and other tools to remove impurities adhering to the surface of the porcelain.
■ Roasting; The product after the shaped surface-cleaning is re-fired in the kiln under a high temperature.
■ Quality analysis: Grade inspection of ceramic products is carried out, sometime test need to be carried out to determine whether the metal content exceeds the standard.
■ Packaging: Ceramics are fragile goods. According to the actual needs during transportation and the value of the products, they are packaged in packaging boxes made of different materials such as paper, wood and brocade.
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GIFT PORCELAIN PRODUCTION