1.What Is “Pottery”?
Pottery is an object made by kneading and shaping clay, which is then fired for hardening. It can roughly be classified into three categories ― earthenware, stoneware and porcelain ― according to various physical conditions including the type of clay, hardness of the biscuit, density, water absorbency and whether it is glazed or not. Criteria for classification of ceramics are slightly different, however, among China, Japan, Korea and Western countries. The following is based on Western classification.
Earthenware
A low-fired ceramic ware that is not fully vitrified and thus has a porous body with a high absorption rate of 10 to 15%. Though the body is rather fragile, it is thermal-shock-resistant and thus suitable for cooking and storing food. Typical examples of earthenware are those with painted decoration produced in ancient China and Japanese Jomon and Yayoi earthenwares.
Stoneware
A vitrified ceramic ware whose body color is not pure white. It is fired at high temperature of around 1100℃ or over. It has a dense, non-translucent body and is usually glazed. Celadon is included in stoneware. In Japan, unglazed high-fired ceramics such as Sue, Bizen, Shigaraki and Tokoname wares are classified as a type of stoneware.
Porcelain
A white ceramic ware that is made of kaolin or China clay, which contains large percentage of vitreous substance. It is glazed and fired at high temperature of about 1300℃. Thinly potted porcelain has a translucent body with almost no absorption (approximately 0.5%) and makes a ringing sound like a metal when struck.
2.Fabrication Techniques
Shaping of clay can be done in various ways, which can be chosen according to the characteristics of the clay (prepared clay ready for working) and the desired form.
Pinching
Hand-building from a lump of clay without using the potter’s wheel or mold. It is the earliest forming technique as observed in the Neolithic period.
Coiling
Building the walls by coiling up ropes of clay, which are luted to make a solid wall. This method is used for forming earthenware or large vessels such as jars.
Slab building
Luting slabs of clay to form square bottles or other square vessels.
Molding
Pouring or pressing clay into a teracotta or wooden mold. It is suitable for mass production or making sculptural, complex forms.
Wheel throwing
Placing a mound of clay on the wheel and lifting up the walls by using the speed of rotation and hand pressure. The structure of the potter’s wheel, the method of rotation and the rotating direction differ by region. Trimming of the surface using the wheel is distinguished from throwing.
Paddling
Beating the surface of the coil-built body with a paddle while holding the inner wall with a wooden flat board in order to refine and solidify the form and surface. The paddled vessel usually reveals patterns of the bumpy surface of the paddle, which prevents the paddle from sticking to the clay body. Paddling also increases the surface area and thus needs less cooking time.
3.Types and Forms of Vessels
Dish (盤)
A shallow and flat vessel.
Bowl (碗)
A smaller-type deep vessel with a wide mouth.
Bowl (鉢)
A larger-type deep vessel with a wide mouth.
Basin(盆)
A large, deep vessel with a wide mouth and base.
Jar (壺)
A vessel swollen from the shoulder to the body with a narrow mouth.
Rice-bale-shaped jar (俵壺)
A jar in the shape of a rice bale with a small mouth and a short neck, occasionally having a foot ring.
Flask (扁壺)
A jar with a flattened body, which was formed by either beating the sides or luting two dish-shaped pieces and applying the mouth and foot ring afterwards.
Bottle (瓶)
A vessel with a small mouth and an elongated body.
Yuhuchun (玉壺春)
A bottle with a small, everted lip, thinly tapering neck and a globular, swollen body.
Meiping (梅瓶)
A bottle with a narrow mouth on a short, upright neck and a broad, high shoulder which tapers towards the base.
Tuluping (吐ろ瓶)
A bottle whose shape is similar to that of the upper half of a meiping. Also called taibozun (太白尊).
Stem cup (高足杯)
A cup in the shape of a small bowl standing on a thin, long leg. It is considered that the form was modeled on metal ware of the west. In China, it became popular especially in the Yuan dynasty and onwards.
Horn-shaped cup (角杯)
A cup in the shape of an animal horn. Originally, such cups were made by hollowing out real animal horns, which later began to be copied in ceramics as well as metal or wood.
Ewer (水注)
A vessel with a handle and a spout.
Covered box (盒)
A vessel consisting of a container and cover that are nearly similar in their shapes and sizes. There are a wide variety of forms, not limited to common round shape or square.
Foot (高台)
A support made on the base of the vessel. It can be made separately and applied after the vessel was formed, or trimmed from the base. It can be called “snake’s-eye” foot or “ring” foot according to its shape. It can also be square to match the form of the body.
Tamabuchi (rolled lip) (玉縁)
Literally translated to “bead edge”, tamabuchi refers to the thickened mouth rim of a bowl, dish or bottle that is made by rolling up the lip. The shape of the section, which is round, gives the name “bead”.
Tatami-tsuki (畳付)
Literally meaning the section touching the tatami-mat (tea bowls for example are placed directly on the tatami-mat when served), the term refers to the base of the foot.
Faceting (面取)
Trimming of the body of a vessel to produce a polyhedral surface. It is often found in bottles and jars as well as in details such as foot rings and spouts.
4.Decorative Techniques
Various techniques are used to decorate ceramic ware.
1.Slip coating
The body is often coated with slip (usually white) when the color of the body is not so fine. The body is then covered with transparent glaze and fired. This technique was popular in Chinese Cizhou ware. In Korea, buncheong ware, which was produced extensively during the first half of the Joseon dynasty, slip coating was done by different techniques including dipping the ware into the slip mixture (known as kohiki 粉引) or paint the slip over the body leaving brush marks (hakeme 刷毛目). Some of them have painted or carved patterns on the white-slip ground.
2.Painting
Applying pigments
Colors or painted patterns applied directly on the bisque-fired earthenware. This decorative method was frequently used in earthenware or Chinese yong (俑, burial figures).
Underglaze painting
Pattern painted in pigments containing cobalt, iron or copper before covering the body with a transparent glaze and firing. Each pigment develops a blue, brown and red color respectively when fired.
Overglaze enameling
Pigments that fuse at low temperature applied to produce patterns on the glost-fired surface, which is then re-fired. White porcelain with polychrome enameling such as red, yellow, green or purple on the ware is called wucai (五彩) in Chinese and iro-e (色絵) in Japanese. Gilt can be added, or it can be combined with underglaze painting.
3.Carving
A pattern is produced on a leather hard body by carving or shaving the surface using carving tools such as a spatula.
Incision, intaglio
Linear decoration cut or engraved into the surface of a ware.
Relief decoration, relievo
Decoration represented in low relief by carving away the background.
Katagiribori
The carving technique in which a knife is held at an angle when carving the outline so that the glaze pools in the carved area, producing a three-dimensional effect.
Openwork
The decorative technique in which a pattern is produced by hollowing out the background. A separately made openwork motif can be applied to the surface.
Sgraffito
The carving technique in which a layer of slip is scratched or carved through to expose the body underneath．The contrasting colors of the slip and body makes the motif outstand effectively. This type of decoration is often observed in Chinese Cizhou ware and Joseon buncheong ware.
4.Impressing
Impressed decoration
Decoration made by pressing a pattern onto the body to produce an impression. It can be achieved by pressing a large block to produce a pattern at once or use a small stamp or roll a cylindrical seal onto the surface to produce a series of patterns.
5.Applying
Sprigging
The process of attaching separately made parts or ornaments (by molding or hand-built) to the body of a ware.
Slip trailing
The process of drawing a pattern directly on the surface of a ware by pouring or squeezing out slip from a slip trailer that has a narrow spout.
6.Inlay
Decoration made by filling a carved or stamped motif with clay of contrasting color, which is then glazed and fired. The technique was widely practiced in Goryeo celadon ware. There is also the reverse inlay technique in which the background of the motif is carved away and inlaid with clay of different color before being glazed and fired.
7.Clay marbling
The technique to form a ware by piling slabs of different colored clay, which is beaten or pressed before forming, producing a marbled effect.
8.Gilding
The process of applying gold onto the glazed surface of a ware. Gold leaf or gold paint was applied using an adhesive substance and fired at low temperature. Gilt wucai (五彩) or five-colored porcelain of the Jingdezhen private kilns produced during the Jiajing and Wanli periods of Ming dynasty China are called kinrande (金欄手) in Japan.
5.The Origin of Glazes and Their Colors
Glaze is a watery suspension that contains vitreous substance, which fuses when fired to produce a thin, glassy layer on the surface of a ceramic ware. It is impervious to liquids and other stains and provides durability and luster to the surface. It is thought that glaze was first found during firing of an unglazed ware, when the ashes from the firewood accidentally fell on the surface of the ware and fused, producing a glassy effect (natural glaze). In addition to the vitreous substance, glaze also contains a flux (which lowers the melting point of another substance) and a coloring agent, producing different colors according to the combinations of substances or firing conditions. There are various ways to categorize glazes: they can be classified by the type of flux, the coloring agent or the color.
1.Glazes classified by flux
Ash glaze
A glaze in which wood ash or lime is used as a flux, fusing at a high temperature of 1250℃ or over. It was already used in Shang dynasty China.
Lead glaze
A glaze in which lead oxide is used as a flux, fusing at a low temperature of approximately 800℃. Well-known examples are the green glaze of the Han dynasty and the sancai or three-color glaze of the Tang dynasty in China.
Alkaline glaze
A glaze in which alkaline substances such as potash or sodium oxide are used as fluxing agents.
Tin glaze
A low firing glaze in which lead and tin are used as fluxing agents. The tin acts to produce an opaque white color.
2.Glazes classified by coloring agents
Copper glaze
A glaze in which copper oxide is used as a coloring agent. It can become green, blue or red according to the fluxing agent and firing technique.
Iron glaze
A glaze in which iron oxide is used as a coloring agent. It can become blue-green (celadon glaze), yellow, brown, kaki (persimmon color) or black according to the fluxing agent and firing condition.
Cobalt glaze
A glaze in which cobalt oxide is used as a coloring agent. There are different sorts of blue, from light blue to indigo blue, according to the fluxing agent and firing technique.
3.Glazes classified by color
Green glaze
A type of low-firing lead glaze in which copper oxide is used as a coloring agent, fusing at low temperature. A brilliant green is produced by oxidizing firing.
Iron-brown glaze
A type of low-firing lead glaze in which iron oxide is used as a coloring agent. A bright iron brown is produced by oxidizing firing.
Cobalt-blue glaze
A type of low-firing lead glaze in which cobalt oxide is used as a coloring agent. A cobalt blue is produced by oxidizing firing.
Black glaze
A glaze in which 8-10％ of iron oxide is added as a coloring agent to an ash glaze. The black color can be achieved by oxidizing firing at high temperature.
Blue glaze
A glaze in which cobalt oxide is added as a coloring agent to a transparent glaze. A vivid lapis-lazuli color is produced by reduction firing.
Red glaze
A glaze in which copper oxide is added as a coloring agent to a transparent glaze. A vivid red color is produced by reduction firing.
Celadon glaze
A glaze in which iron oxide is added as a coloring agent to an ash glaze. It turns into blue-green by reduction firing. When it is oxidized, the color changes into yellow-brown or yellow, which is called “rice-color celadon” in Japan.
Transparent glaze
A high-fired ash glaze with extremely few iron content. Since it turns transparent under reduction firing, it is used in white porcelain and underglaze painted decoration on a white-porcelain body.
6.Firing Techniques and Kilns
Firing of ceramics began with a primitive method, which gradually transformed and developed into more sophisticated, efficient techniques.
Open firing
Firing by placing the pots on the ground and covering them with fuels such as wood or grass. The pots are always exposed to the air, which means they are fired in an oxidizing atmosphere. Since the temperature does not exceed around 800℃, earthenware is the only suitable ware to be fired in this method. In some cases, a shallow pit is dug into the ground.
Anagama, Bank kiln, Dragon kiln
A tunnel kiln built on the hillside, which consists of a door to stoke the fuel and a fire box on the lower end, the firing chamber and a flue through which smoke is sent out. For greater efficiency, kilns with steeper slope or longer chambers are built. These kilns are called climbing kiln (noborigama) or dragon kiln (long kiln in Chinese). A more sophisticated variant of the climbing kiln is the multi-chambered climbing kiln that has many separate chambers.
Horse-shoe shaped kiln
A kiln built on a flatland, named after its shape in plan. Beginning with a fire box at one end, it has a firing chamber in the center and a chimney at the other end. This type of kiln is found chiefly in northern China. Also called mantou (bread roll) kiln or domed kiln.
Muffle kiln
A small kiln for second firing of wares with overglaze enamel decoration. The average firing temperature is 700-800℃.
Oxidizing atmosphere
Firing atmosphere containing sufficient oxygen and thus combustion of the fuel is complete. In this atmosphere, iron becomes yellow and copper turns green.
Reducing atmosphere
Firing atmosphere in which the amount of oxygen is in short supply, thus combustion of the fuel is incomplete. Oxides become deprived of oxygen and thus reduced into their original elements. In such atmosphere, iron becomes blue-green and copper becomes red.
Saggar
A refractory container into which pottery is placed during firing, preventing the pot from being exposed to fly ash or contact with other pots. They can be stacked when loading pottery into the kiln, thus enabling efficient use of kiln space. Saggar can be cylindrical or M-shape according to the region or period in which it was used.
Spur marks
Marks on the base or interior of the pottery made by stilts, sand, stone or other objects used to support the ware during firing. Stilts were made of various materials and had diverse forms according to the region or period of production, giving different sizes and shapes of spur marks.
7.Motifs and Symbols
The motifs decorating ceramic ware represent different meanings.
Dragon (龍)
An imaginary animal that is thought to be controlling Heaven, legends saying that it lives in the waters and runs through the air. The prototype of the dragon can be found in Neolithic painted ceramic wares or bronze vessels of the Shang and Zhou dynasties. Closely associated with cloud and rain, dragons are often depicted together with cloud or wave patterns. The use of dragon motifs by the general public was prohibited later, when it became the symbol of the emperor.
Phoenix (鳳凰)
Phoenix is a legendary animal closely associated with the wind, and thought to be the king of birds. Phoenix motifs can be found in Neolithic painted ceramic wares or bronze vessels of the Shang and Zhou dynasties. The male feng (鳳) and the female huang (凰) are often depicted in pairs.
Tiger (虎)
Tiger motifs also appear on bronze vessels of the Shang and Zhou dynasties. While dragons and phoenixes are imaginary animals, tigers have been inspiring people with awe as the strongest animal on earth. Later they became to believe that the animal drives away evil spirits, thus it was often adopted as a motif in various ceramic and bronze vessels. Many examples of tiger motifs are also found outside China, such as Joseon ceramics and Japanese Arita porcelain.
Fish (魚)
Fish is an auspicious symbol for richness, for the Chinese word for fish “yu (魚)” is phonetically identical with the word “yu (余)”meaning abundance. It also has a meaning of flourishing posterity, since fish lay many eggs. Fish can be depicted in pairs or in combination with water plants or wave patterns. It was widely adopted in buncheong ware of the Joseon dynasty.
Bat (蝙蝠)
Bat is an auspicious symbol for happiness, for the Chinese word for bat “fu (蝠)”is pronounced the same way as the word for happiness “fu (福)”. Bat motif was widely used especially during the Qing dynasty.
Peony (牡丹)
The colorful large blossoms make peonies the king of flowers. It also represents richness and honor. Peony became widely used as a motif during the Song dynasty in China.
Lotus (蓮)
Closely associated with Buddhism, lotus is a symbol for purity, for the beautiful flower grows out of the mud. Since lotus spreads its roots wide and produces many seeds, it also represents thriving posterity. Lotus motif was often combined with fish and water fowls, depicting a scene on the shore of a lotus pond.
Baoxianghua (宝相華)
An imaginary flower made by combining the elements of a variety of flowers including peony, lotus and pomegranate. It was widely used during the Tang dynasty in China, retaining its popularity as a motif in ceramics since then. It was also introduced to the Korean Peninsula and Japan.
Pine, bamboo and plum blossom (松竹梅)
The three plants that survive the winter retaining their leaves and bearing fragrant blossoms are symbols for vitality and rebirth. They are also called “three friends of winter (sui han san you 歳寒三友)”
Pomegranate, grapes (石榴、葡萄)
Since pomegranates and grapes bear many fruit and seeds, they are symbols for abundance and flourishing posterity. The motifs were imported from West Asia.
Peach (桃)
The symbolic meaning in peach, which is longevity, originates from a legend in ancient China of a peach tree that brings longevity, bearing fruit only once in three thousand years.
Eight precious things (八宝)
This is a combination of eight precious things selected from the eight auspicious emblems derived from Lamaism, which are the wheel of law, conch shell, canopy, umbrella, lotus, vase, paired fish and endless knot, along with other auspicious symbols such as the wishing jewel, coins, lingzhi and rhinoceros horns.
