Goryeo ware

Goryeo ware (Korean: 고려도자기, romanized: Goryeo dojagi, also known as Goryeo cheong-ja) refers to all types of Korean pottery and porcelain produced during the Goryeo dynasty, from 918 to 1392, but most often refers to celadon (greenware).
Celadon techniques were first introduced from China; Goryeo potters established a native style by the 12th century. One of these native styles is characterized by the sanggam technique, a way of inlaying that was unique to Goryeo celadon. The color of the celadon, called bisaek for 'green', was also highly admired. The industry arose and declined as the Goryeo dynasty developed. Many wares were produced at the Gangjin Kiln Sites in southwestern Korea.
An artist of the post-war era who specialised in Goryeo ware was Living National Treasure Yu Geun-Hyeong. His work was documented in the short film Koryo Celadon in 1979. Many celadon pieces from Goryeo are listed as National Treasures of South Korea.
Pottery and celadon had been introduced into the Korean peninsula in the Three Kingdom age. Demand for higher quality porcelain increased as the Goryeo Dynasty emerged. Along with the development of tea culture and Buddhism, wares based on traditional and southern China (Song dynasty) porcelain began production in Goryeo . Most of the pottery made in this era are the kinds that are called haemurigup celadon and green celadon (low-grade)
As the celadon techniques of the Song dynasty reached its pinnacle, much effort was made inside Goryeo to reproduce the turquoise coloring of these Chinese porcelain. A lot of kilns were made throughout the kingdom, leading to a variety of celadon being made. High grade celadon were made in order of the capital, and low grade celadon were made by the requests of temples, offices and local families of provinces.
Though Chinese influences were still existent, Goryeo styled shapes and decorations emerged in some porcelains. These are characterized by the utilization of light curves and a serene, elegant feel. Decoration techniques such as relief carving, intaglio carving, iron oxide glaze, openwork became in use. The sanggam inlaying also started at this age.
The 12th century is considered as a zenith of Goryeo celadon, especially in its special color and harmony. The pure celadon made in this age had thin glaze coating that exquisitely reflected the jade color, called bisaek. They also had a great level of structural balance and elegance. There are records describing celadon of this age as world best.
Jinsa "underglaze red", a technique using copper oxide pigment to create copper-red designs, was developed in Korea during the 12th century, and later inspired the "underglaze red" ceramics of the Yuan dynasty.
Maturation of the aristocrat society due to events such as the coup of military officers leads to an increasing favor for extravagantly decorated porcelain. Inlaying techniques reach its height and opens a second zenith of Goryeo celadon. Other types of porcelain develop as whitening, iron oxide glaze, copper oxide glaze came in use. With the decrease of Chinese influence, Goryeo celadon acquires a more native shape, in unique patterns and decorative shapes. Thin, transparent glaze used to show the inlaid designs led to development of a crackling cooling pattern, called bingyeol (craquelure).
After the Mongolian invasion in 1220, social and economic confusion had caused the general quality of Goryeo celadon to decline. Influence of Yuan dynasty is seen throughout the porcelain produced in this time. Though the celadon industry remained, overall density of expressions and smoothness decreased and the color and harmony are also diminished. This decrease in its beauty continues as the Goryeo dynasty recedes.
In the late 14th Century, the Kilns of Gangjin and Buanyo were attacked by Japanese pirates and closed. Inland kilns replace them, putting an end to the age of celadon. Though new characteristic shapes and designs appear, they are utilitarian instead of being elegant and restrained, as Goryeo celadon in its zenith did. One of these new types of porcelain is called buncheong.
In the late 19th century, the Japanese, who occupied Korea at the time, began to be unearth Goryeo era celadon wares from the Royal Tombs of the Goryeo Dynasty near Kaesong in todays North Korea. These became the most sought-after item in the Korean art market. The Japanese resident-general of Korea, Ito Hirobumi, who previously served as Japan's first prime minister, collected over 1000 works which were sold by antique dealers in Seoul. Japanese industrialist Tomita Gisaku is credited with rediscovering how to make Goryeo style wares at his factory named Sanwa Goryeo Celadon. It was established in 1908 in the town of Nampo in South P'yong'an Province, todays North Korea. In 1912, Umii Benzo established a competing factory named Kanyo K̄oraiyaki located in todays Jangchung-dong district of Seoul. Umii's firm opened a branch to sell celadons in Tokyo and both firms began supplying wares to Japanese tourists visiting Korea. Korean ceramist Yu Geun-Hyeong (b. 1894 d. 1993), who worked in Umii's factory early in his career, is credited with experimenting with techniques, kiln design, clays, and glazes to more accurately reproduce Goryeo era wares. Owing to his work, Yu was designated a Living National Treasure of South Korea. North Korean potter U chi-son is also credited as leading the way to recreated Goryeo celadon pottery.
Even after World War II, when Japanese control of Korea ended, most 20th century Goryeo ware were still shipped to Japan for sale in department stores like Mitsukoshi. In the late 1970s, Korean ceramist Shin Sang-ho (b. 1947) is credited with modernizing production of celadons when he brought back a gas-fired kiln from Japan.
For the inlay technique, several patterns are engraved on the surface of metal, clay, wood, etc. This traditional decoration technique started to be applied in porcelain in the Goryeo dynasty. Purple (black) and white clay were used to show the patterns.
A pattern is engraved on the vessel's body with a knife and the carved-away areas are filled with purple or white clay. When the clay dries the excess is removed, leaving it only in the carved areas, leaving a white or purple pattern. The entire vessel is coated in a colorless glaze. Once it is fired, the white clay still appears white but the purple turns black, and the pattern is visible through the glaze.
Glaze of Goryeo celadon had a definite composition starting from the 11th century to the 15th century. It contained a lot of calcium in composition, with 0.5% of manganese oxide, which was more concentrated than glaze used in Chinese celadon. Also in the case of Chinese ceramics, there is enough time for nucleation-crystal growth, so it takes jade color. But the kilns in Goryeo were smaller than that in China, so the firing and cooling process took place quickly. Therefore, minerals in the glaze such as anorthite or wollastonite did not have sufficient time for nucleation-crystal growth. This results in the color of celadon being closer to the gray side. In Goryeo celadon, quartz, black particles, bubbles, cracks can also be observed.