Chairman
"Ours are a resourceful and civilized people who have developed science and culture since ancient times, thus rendering a great contribution to enriching the treasure-house of human culture."
Glass, an amorphous solid, is one of the important substances that has been used since long time ago by humankind along with stone and metals. Today, it has dozens of kind depending on its composition and usage, and is widely used as an indispensable material for our life and production practice.
Glass was made and used as various personal ornaments in ancient times as early as thousand years ago in our country. Its long history is illustrated by the discovery of glass beads of different colors in coffin tombs, supporting framework tombs, and brickwork tombs in different parts of ancient Korea, near Pyongyang in particular. Chemical analysis of those glass beads reveals that in ancient times glass manufacturing skill developed independently and was on a high level in our country.
The most remarkable one in glass manufacturing in our country of ancient times is that our ancestors invented lead glass very early and developed their glass manufacturing independently based on this skill. Lead glass, which is made by adding high content of oxidized lead, has high density, refraction and dispersion rate, and melts at a low temperature, so easy to process, which is why it is widely used for making high-refracting optical glass, vacuum tube glass, ornamental glass, expensive glass of everyday use, glass for light lamps, glass for cutting off radioactive rays and so on. Considering the fact that this kind of lead glass was first produced at around 1675 in other parts of the world, it is remarkable that our ancestors made it as early as ancient times, demonstrating their high glass manufacturing skill. The content of oxidized lead was mostly over 15% and sometimes over 25%: for example, the light blue or light green beads from different historical remains such as the Tomb 167, Jongback-dong, the Tomb 27, Rangnang-dong, the Tomb 16-2, Rangnang-dong, and others are mostly of soda-glass and typical soda-lead glass whose average oxidized lead content is over 20%. Meanwhile, white beads from some remains such as the Tomb 33, Rangnang-dong, are of potassium-lead glass. As mentioned, our ancestors made glass beads of high quality mostly with soda-lead glass.
Next, the glass made in ancient Korea is unique in its composition. Glass made in ancient and medieval Egypt, Central Asia, west Europe was mostly of Si-Na-Ca system, Si-Na-Ca-Mg system, Si-Na-Ca-Mg-Al system, Si-K-Ca-Mg-Al system and so on, and Japan made glass of Si-Pb system which is lead glass system, and Si-Na-K-Ca system which is the glass of alkalinity. But glass beads made in ancient Korea were mostly of Si-Na-Pb system, Si-K-Pb system, and Si(Al)-K-Pb system.
This shows glass manufacturing skill in ancient Korea was on a high level and developed independently, mainly based on lead glass manufacturing skill.
Another remarkable thing is that they used different oxidized metals to make glass beads of different colors, shapes and sizes. Glass beads in the period of ancient Korea, found in the tombs near Pyongyang, were of different colors; blue, indigo blue, pale yellow, black, dark-red, white and so on, so they were good accessories of high ornamental value. Our glass manufacturers made glass beads of different colors, using, as coloring agents, different oxidized metals such as iron oxide(Fe2O3, FeO, Fe3O4), oxidized manganese(MnO2), oxidized cobalt(CoO), oxidized copper (CuO, Cu2O), oxidized antimony(SbO) and others. These oxidized metals, depending on their content, oxidation and deoxidization process, could add various colors, which is why they are widely used even in modern glass manufacturing industry.
They are also of different shapes and sizes. Beads for earrings had bugle-and apricot-leaf shapes while beads for necklace were cylinder-shaped, disk-shaped, circular or oval shape, polyhedron-shaped. As for their sizes, normal ones were 0.2-0.65cm, bigger ones were 1.5-3cm in diameter, while some others were the size of grains of hulled millet or sorghum. This shows they were possessed of high skill of making glass products of different shapes and sizes.
Indeed, Koreans, the resourceful and talented people who invented and developed glass manufacturing skill of high level as early as ancient times, greatly contributed to the development of human culture.
