Ceramics, also known as pottery, can be divided into two main types: earthenware, for which the raw material is made from soil, and porcelain, made from stone powder. For earthenware, the soil is mixed well with water to make a smooth clay, which is then shaped into dishes, pots, vases or other items and then placed in a high-temperature oven called a kiln. The same process is done for porcelain, except the stone powder is evenly mixed after being crushed into finer pieces.
There are many types of pottery because each type developed differently in various parts of Japan, with the craft often bearing the name of the region where it was made.
1 Preparing clay
First, select high-quality soil or stone, and then make it into wet clay.
2 Forming shapes
A potter's wheel is used to shape dishes, pots and vases.
Other common methods are using coils of clay that are layered to create forms or building up thin slabs of clay into three-dimensional objects.
3 Bisque firing
Unglazed pieces of pottery are fired at temperatures of between 600 and 950℃ (1112 and 1742℉), which hardens them and makes them easier to glaze.
The surface of the pottery is coated with a glaze which after firing, serves the purpose of decorating and hardening the piece.
5 Kiln firing
The length of time and temperature of firing depend on the piece's clay or glaze type. After the ceramic has been fired and hardened, it is complete.
For iron glazing (called tetsu-e in Japanese), designs are painted with pigment containing iron oxide (rusted iron), then coated with a glaze that turns transparent during firing, and fired at a high temperature. This is a basic method of producing decorative ceramics, utilizing the way iron changes colors when fired.
Blue and white pottery
Blue and white pottery (called sometsuke in Japanese) is made by painting designs on white bisque fired pottery with a cobalt-rich pigment known as gosu or zaffer. It is then coated with a transparent glaze and glaze fired. This technique has been used in China since the Yuan Dynasty (around the 12th century).
Iroe or color painting is a technique of applying and firing a transparent glaze. Then, paint is applied over the glaze and the piece is fired again at a temperature of approximately 800℃ (1472℉). This is why it is also known as over-painting. The paint used in traditional color painting is known as wa-enogu (Japanese-style paint), and color choices include red, blue, yellow, green, and purple. It is also possible to use yo-enogu (Western-style paint).
Celadon glaze porcelain
This technique originates from China and uses white stone to produce porcelain clay. Called seihakuji in Japanese, it is porcelain that has been bisque fired and painted with a glaze containing a small amount of iron, which turns a bluish tint when fired again. There is also hakuji (white porcelain), which is painted with a glaze that turns transparent when fired, and seiji (blue porcelain), made with clay that turns blue when fired.
When using the zogan or ceramic inlay technique, the surface of the pottery is carved and then clay of other colors is inlaid in the carved-out areas to make a design. After the clay is inlaid, a glaze is applied, the piece is glaze fired, and it is complete.
Neriage or clay kneading is made by piling up and kneading together different colors of clay. All sorts of patterns can be produced depending on the method used to combine the clay colors, with cross-sections of kneaded clay appearing on the surface of the ceramics. Different colors of clay contain different elements, and care must be taken to make sure that the piece doesn't break or come loose. The completed pottery will have the same pattern on its exterior and its interior.
- "What Are Traditional Crafts? -A Guidebook to Seeing, Learning, and Enjoying-" Edited by the Japan Kogei Association Eastern Branch. Published by Unsodo
The most notable aspect of Hasami yaki is the beauty of its white porcelain and quasi-transparent indigo blue gosu porcelain. Also this craft has kurawanka bowls, sake export bottles and break resistant tableware.
The clay used in Mashiko yaki is rich in silicic acid and iron with a high plasticity, making it easy to shape and highly fire-resistant. Unlike other potteries, no extra ingredients are added to the clay which is the secret behind the thick texture.
The distinct features of Kutani yaki are vivid colors, bold and elegant designs, and a particular technique of overglaze enamel painting. This technique consists of using pigments to paint a pattern incorporating flowers, birds, or natural scenery over a glaze and then firing the piece again.photo: Ishikawa Prefecture
Shigaraki yaki uses coarse soil, is highly fire-resistant and acquires pink or other shades of red during the firing process, becoming red with scarlet or brown overtones. Due to ashes from the kiln sticking to the surface, the clay takes on a scarlet glow and warm coloring, a characteristic unique to this craft.