고려청자 色의 시대 : 비색청자 유약의 성분과 미세구조 분석 (The color of the Goryeo celadon: composition and microstructure of pi-saek celadon)

서지정보

· 발행기관 : 국립중앙박물관
· 수록지 정보 : 미술자료 / 83호 / 221 ~ 244페이지
· 저자명 : 이영은

초록

In the Goryeo dynasty from 11th to 12th century, Goryeo craftsmen achieved highly advanced techniques with their aesthetic sense, they finally produced beautiful bluish green celadon with Pi-saek(luminous jade-green color of Goryeo celadon) glaze.
This essay will discuss the contemporary manufacturing techniques of celadon in the 12th century. The high quality celadon unearthed from the kiln site no.7 at Sadangri and the kiln site no.12 at Ucheolli, Puan, is regarded as Pi-saek celadon. By comparison of the shards from the kiln site no.63, no.36 and no.9 at Yongunri, Kangjin, we will discover Goryeo craftsman’s attempt to achieve the ideal color of celadon. It will be analyzed by the developing process of glaze-production techniques during about 200 years from the earliest celadon to Pi-saek celadon. Furthermore, the influential relation in techniques will be discussed by comparison of the Ru wares and Goryeo celadon.
The composition of glaze was analysed by Energy dispersive X-ray spectrometer equipped with scanning electron microscope(SEM-EDS) and electron probe micro-analyzer(EPMA), the color of celadon was measured by spectrophotometer. Wet Chemical method, KS E3016 was applied to analyze iron ion state.
Lime glazes which use calcium as a flux was applied to produce the early celadon to the Pi-saek celadon. It proves that different types of clay material, mixing ratio of wood ashes and other types of ashes were applied into celadon glazes of Yongin kilns, Kangjin kilns, and even other kilns at Kangjin according to different periods and kiln sites. Celadon glazes of the kiln site no.7 at Sadangri where stabilized blue-colored glaze were produced, indicates slightly higher lime, but lower alkali in component when comparing with glazes from the kiln site no.9 at Yongunri.
The main coloring agent in Goryeo celadon glaze is iron. The ratio of two iron oxidation state, Fe2+ and Fe3+, is a crucial element to determine the glaze color along with the overall contents of iron. In the glazes of Seori, Yongin, 2 ～3% of iron oxide and 1% of highly rated titania are detected. The kiln site no.63 of Yongunri, one of the earliest Kangjin kiln complexes, shows the chemical compositions remarkably lower in iron and titanium than those of Seori. When the celadon at the kiln site no.7 at Sadangri in Kangjin, came to the so-called pi-saek era, the composition of its glaze is the iron oxide lower than 1.5% and titania lower than 0.2% that indicates the lowest level among the kiln site no.36 and no.9 of Yongunri, Kangjin.
High and low level of iron oxide and titania is the primary composition of glazes at the times. This characteristic of the glaze also consistently appeared in the glaze produced in Yucheolli, Puan which locates 150km away from Kangjin.
Consequently, beautiful glaze color of Goryeo celadon is achieved by controlling coloring agents and proportion of components influenced by firing atmosphere, that is a percentage of Fe2+ and Fe3+ which leads diverse colors. Goryeo people at the time gradually reduced coloring agent and controlled the adequate atmosphere of reduction to achieve the most desired colors.
The Pi-saek celadon is distinctively characterized by its translucent glaze. The translucent glaze in which contains bubbles, is different from Chinese glaze. Diverse elements such as firing time, speed of raising temperature, its duration of a high temperature, cooling rate, and controlling the atmosphere of kilns influence the color of celadon and its texture crucially. Absence of anorthite in Goryeo celadon means holding time in high temperature was short and cooling speed rapidly proceeded. This implies that the material of clay kiln would be related with the kiln structure of Goryeo celadon. Consequently the high-fired translucent glaze containing volumes of bubbles is higher in calcium, thus it can transform to ceramic relatively in low temperature. Furthermore, it is also related to the vitrification in short time and structures and materials of a kiln which cools rapidly the glaze down.
The method of two-step firing is the best choice to achieve moderate thickness of Pi-saek glazes and to increase the degree of completion of glazed ceramics. It seems that Goryeo potters gradually controlled the thickness of glazes to get the finest glaze color. The thickness of late Goryeo celadon glaze had been gradually thicker than that of early one. The thickness of early celadon was less than 200 micron, but the thickness of celadon from the kiln site no.7 at Sadangri and no.12 at Ucheolli, dated to 12th century reaches 400 ～ 800 micron.
The middle layer between body and glaze is not shown in the Goryeo celadon. This implies there was not enough time for the vitreous glaze to permeate into body. Also, 18% of alumina content in body, which is comparably lower than Chinese northern celadon, is a difficult condition to produce anorthite. Absence of middle layer in Goryeo celadon increases transparency of Goryeo celadon glazes.
Firing techniques made gradual progress. The adequate controls of the reduction atmosphere produce unique pi-saek color and the kiln atmosphere which maintains high temperature shortly and rapidly cools down provides clean and transparent glaze. These firing techniques are completely different from Chinese Ru yao production techniques. As a result, noticeable differences between Goryeo celadon and Ru wares resulted from material and building techniques of a kiln and its firing techniques. Furthermore, by developing firing techniques adapted to the kiln structure, the highest effect was created in the celadon with lime glaze.
Goryeo celadon was the preeminent craft with advanced technology at the time when the celadon was produced. Anonymous potters ceaselessly attempted to achieve the production techniques of these fine celadon wares, finally the masterpieces were produced.
Goryeo potters fully apprehended characteristics of the applied material and therefore they could obtain the most satisfactory colors and textures through diverse experiences and experiments.

영어초록

In the Goryeo dynasty from 11th to 12th century, Goryeo craftsmen achieved highly advanced techniques with their aesthetic sense, they finally produced beautiful bluish green celadon with Pi-saek(luminous jade-green color of Goryeo celadon) glaze.
This essay will discuss the contemporary manufacturing techniques of celadon in the 12th century. The high quality celadon unearthed from the kiln site no.7 at Sadangri and the kiln site no.12 at Ucheolli, Puan, is regarded as Pi-saek celadon. By comparison of the shards from the kiln site no.63, no.36 and no.9 at Yongunri, Kangjin, we will discover Goryeo craftsman’s attempt to achieve the ideal color of celadon. It will be analyzed by the developing process of glaze-production techniques during about 200 years from the earliest celadon to Pi-saek celadon. Furthermore, the influential relation in techniques will be discussed by comparison of the Ru wares and Goryeo celadon.
The composition of glaze was analysed by Energy dispersive X-ray spectrometer equipped with scanning electron microscope(SEM-EDS) and electron probe micro-analyzer(EPMA), the color of celadon was measured by spectrophotometer. Wet Chemical method, KS E3016 was applied to analyze iron ion state.
Lime glazes which use calcium as a flux was applied to produce the early celadon to the Pi-saek celadon. It proves that different types of clay material, mixing ratio of wood ashes and other types of ashes were applied into celadon glazes of Yongin kilns, Kangjin kilns, and even other kilns at Kangjin according to different periods and kiln sites. Celadon glazes of the kiln site no.7 at Sadangri where stabilized blue-colored glaze were produced, indicates slightly higher lime, but lower alkali in component when comparing with glazes from the kiln site no.9 at Yongunri.
The main coloring agent in Goryeo celadon glaze is iron. The ratio of two iron oxidation state, Fe2+ and Fe3+, is a crucial element to determine the glaze color along with the overall contents of iron. In the glazes of Seori, Yongin, 2 ～3% of iron oxide and 1% of highly rated titania are detected. The kiln site no.63 of Yongunri, one of the earliest Kangjin kiln complexes, shows the chemical compositions remarkably lower in iron and titanium than those of Seori. When the celadon at the kiln site no.7 at Sadangri in Kangjin, came to the so-called pi-saek era, the composition of its glaze is the iron oxide lower than 1.5% and titania lower than 0.2% that indicates the lowest level among the kiln site no.36 and no.9 of Yongunri, Kangjin.
High and low level of iron oxide and titania is the primary composition of glazes at the times. This characteristic of the glaze also consistently appeared in the glaze produced in Yucheolli, Puan which locates 150km away from Kangjin.
Consequently, beautiful glaze color of Goryeo celadon is achieved by controlling coloring agents and proportion of components influenced by firing atmosphere, that is a percentage of Fe2+ and Fe3+ which leads diverse colors. Goryeo people at the time gradually reduced coloring agent and controlled the adequate atmosphere of reduction to achieve the most desired colors.
The Pi-saek celadon is distinctively characterized by its translucent glaze. The translucent glaze in which contains bubbles, is different from Chinese glaze. Diverse elements such as firing time, speed of raising temperature, its duration of a high temperature, cooling rate, and controlling the atmosphere of kilns influence the color of celadon and its texture crucially. Absence of anorthite in Goryeo celadon means holding time in high temperature was short and cooling speed rapidly proceeded. This implies that the material of clay kiln would be related with the kiln structure of Goryeo celadon. Consequently the high-fired translucent glaze containing volumes of bubbles is higher in calcium, thus it can transform to ceramic relatively in low temperature. Furthermore, it is also related to the vitrification in short time and structures and materials of a kiln which cools rapidly the glaze down.
The method of two-step firing is the best choice to achieve moderate thickness of Pi-saek glazes and to increase the degree of completion of glazed ceramics. It seems that Goryeo potters gradually controlled the thickness of glazes to get the finest glaze color. The thickness of late Goryeo celadon glaze had been gradually thicker than that of early one. The thickness of early celadon was less than 200 micron, but the thickness of celadon from the kiln site no.7 at Sadangri and no.12 at Ucheolli, dated to 12th century reaches 400 ～ 800 micron.
The middle layer between body and glaze is not shown in the Goryeo celadon. This implies there was not enough time for the vitreous glaze to permeate into body. Also, 18% of alumina content in body, which is comparably lower than Chinese northern celadon, is a difficult condition to produce anorthite. Absence of middle layer in Goryeo celadon increases transparency of Goryeo celadon glazes.
Firing techniques made gradual progress. The adequate controls of the reduction atmosphere produce unique pi-saek color and the kiln atmosphere which maintains high temperature shortly and rapidly cools down provides clean and transparent glaze. These firing techniques are completely different from Chinese Ru yao production techniques. As a result, noticeable differences between Goryeo celadon and Ru wares resulted from material and building techniques of a kiln and its firing techniques. Furthermore, by developing firing techniques adapted to the kiln structure, the highest effect was created in the celadon with lime glaze.
Goryeo celadon was the preeminent craft with advanced technology at the time when the celadon was produced. Anonymous potters ceaselessly attempted to achieve the production techniques of these fine celadon wares, finally the masterpieces were produced.
Goryeo potters fully apprehended characteristics of the applied material and therefore they could obtain the most satisfactory colors and textures through diverse experiences and experiments.

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