Porcelain is a type of ceramics that does not lose its beauty over time. With careful handling, it can serve and please the eye forever. There are various types of porcelain, differing in their composition and manufacturing method.
The word "porcelain" as a term includes all pottery, both white and translucent. The Chinese introduced the world to china. By the way, they made not only dishes from porcelain, but also benches, gazebos, musical instruments, etc.
Types of porcelain and features of its manufacture
All existing porcelain today can be divided into three groups: European hard porcelain; soft porcelain, or semi-porcelain, and oriental porcelain. Eastern and European ceramics are made on the basis of kaolin, which includes clay and feldspar. For the production of European porcelain, a greater amount of kaolin is required than for the production of oriental, besides, the procedure for firing it is carried out at a higher temperature. This gives the final product more transparency, but there is also a drawback - the absence of all colors except blue. That is why European porcelain is painted over glaze, while oriental porcelain provides for underglaze painting.
By its structure, porcelain can be hard or soft. Solid is more than half of kaolin and a quarter of quartz. The rest of it is occupied by feldspar. Bone china is a type of hard china and consists of 50% bone ash. It is distinguished by a special whiteness, thinness and translucency. Soft porcelain is more diverse in chemical composition and requires more gentle heat treatment. The fusible glaze, making it look like Chinese porcelain, allows for thicker writing and much softer tones.
Production technology
The prepared mixture, consisting of clay, quartz, kaolin and other materials, is poured into special plaster molds, hollow inside. As the water contained in the solution accumulates in the gypsum, the outer layer of the workpiece hardens. The more it costs, the more wall thickness it gets. The unnecessary solution is drained, and the workpiece is prepared for painting or for further firing - polished, deburred, etc. Complex things are assembled from several parts.
If paints are applied to untreated porcelain, covered with transparent glaze and placed in a kiln for firing at a temperature of 1350 ° C, this method of painting is called underglaze painting. During firing, the paint is fused into the glaze and makes it possible to obtain a shiny product with improved properties, as well as indicators of strength and resistance to mechanical and chemical damage. Overglaze painting has a richer palette of colors. For firing such products, a temperature of 780–850 ° C is sufficient.
Bone china is fired at a lower temperature than hard porcelain. For overglaze painting, compositions based on gum turpentine and turpentine oil are used. Underglaze paint is diluted with water and sugar with the addition of a small amount of glycerin.
