Pottery can be broadly classified into earthenware, ceramic, stoneware, and porcelain.
Stoneware is opaque, non-porous and generally colored.
It can be either unglazed or glazed.
It is distinguished from pottery by its lack of porosity and from porcelain by its opacity.
The term stoneware was chosen by engineers around 1907 (1907), and stone is a neologism for stone.
The range of items belonging to this category is wide and includes both decorative and utilitarian items.
Practical items include building utensils, kitchen utensils, sanitary ware, chemical products, earthenware pipes, and so on.
Stoneware is often made of a single type of clay, sometimes mixed with two or more types of clay.
Some are left as raw clay, some are water-fired, and some are mixed with especially refractory unclay.
It is usually fired in a zeigel pyramid (No. 8 or higher), but some stoneware can be made at lower heat levels.
The base material is clay, which gives it plasticity and therefore sufficient refractoriness, and it does not distort when fired.
Stoneware in Japan is produced in Soma, Mashiko, Kasama, Tokoname, Banko, Shigaraki, Marubashira, Onshi, Ibe, Hagi, Takatori, Takata, etc.
Stoneware is sometimes covered with a decorative clay and painted with underglaze colors, such as cobalt, floral azure, and manganese chrome.
Unglazing is usually omitted.
The glazes are often salt glazes, and mineral glazes such as lime, feldspar, ash, and bristol glazes are used.
In our country, ash glaze is often used.
For example, white hagi glaze, aku glaze, raitai-ishi glaze, sea squirt glaze, etc.
The base clay of decorative stoneware is mainly water-weathered clay, but it is not unusual to add kaolin, feldspar, quartz, or base powder to it.
The color of the clay is usually gray, yellow, or white, but dark brown is also possible.
Most glazes are lime glazes, but lead glazes are also used on rare occasions.
After the base was unglazed, it was decorated with underglaze enameling, colored glazes, and overglaze painting.
Sometimes a decorative clay is applied, and in rare cases a salt glaze is applied, as in the case of Ibe ware.
Blue Ibe, by the way, is the result of iron reduction.
Decorative stoneware is often indistinguishable from fine stoneware, except that the base clay is slightly coarser.
Fine stoneware, like fine pottery and porcelain, has a fine clay.
The difference between stoneware and porcelain is that it lacks transparency and is tinted.
Fine stoneware was most developed in England.
Stoneware kilns vary from region to region and from kiln to kiln, depending on the type of product.
The native kilns in Japan resemble the old kilns, but some are much lower and smaller, with steeper slopes and shorter firing times.
