1-A : Main Features
Pottery (Touki = 陶器)
– makes dull sound when hit
– warm and hand-made feeling
– keep contents warm
– has absorbability
– no transparency
– fired by 1000~1280℃
– brownish color
Porcelain (Jiki = 磁器)
– makes clear metal sound when hit
– no absorbability
– has transparency
– easy maintenance
– fired by 1250~1350℃
1-B : How the difference comes from?
< Colors >
Pottery is brown and porcelain is white. This difference comes from their raw materials.
Pottery is basically made from clay which contains iron and this iron turns out to be dark color. Glazes used on pottery are generally colored, such as Tenmoku, Kizeto, Shino, and Oribe.
Porcelain is made from white clay (called kaolin) which contains less iron or made from mixture of porcelain stone with feldspar and silica stone; therefore, porcelain is white. Glazes used on porcelain are generally transparent in order to set off the white color of porcelain.
< Density >
Their densities are different as well. While raw material (clay) is being fired, glass material is formed by reaction and it covers and fills tiny air pockets in the raw material. By filling these air pockets, absorbability of clay decreases, and when raw material contains more glass material, it will have more transparency.
Porcelain has more density than pottery does, since the raw material of porcelain has more glass materials (feldspar and silica) and it is fired by higher temperature. (In general, pottery’s absorbability is 5% and porcelain is less than 0.1%.)
< Thickness and Thermal Conductivity >
Pottery is thicker than porcelain because of its density and material, and it generally keeps temperature of its content longer than porcelain does. This is from the density of material, that is, air pockets in pottery provides lower conductivity.
Both pottery and porcelain have merits and demerits. In general, pottery is for a gift, hobby, home use, and small restaurants, and porcelain is for hotels, restaurant chains, and home use. Knowing more about features of each ceramics will help you figure out what type of ceramics will be the best choice for you.