''Keum-boo'' ({{Korean, hangul=금부; also ''Geumbu'', ''Kum-Boo'' or ''Kum-bu''— Korean "attached gold") is an ancient

Korea Korea is a peninsular region in East Asia consisting of the Korean Peninsula, Jeju Island, and smaller islands. Since the end of World War II in 1945, it has been politically Division of Korea, divided at or near the 38th parallel north, 3 ...

gilding Gilding is a decorative technique for applying a very thin coating of gold over solid surfaces such as metal (most common), wood, porcelain, or stone. A gilded object is also described as "gilt". Where metal is gilded, the metal below was tradi ...

technique used to apply thin sheets of

gold Gold is a chemical element; it has chemical symbol Au (from Latin ) and atomic number 79. In its pure form, it is a brightness, bright, slightly orange-yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal ...

silver Silver is a chemical element; it has Symbol (chemistry), symbol Ag () and atomic number 47. A soft, whitish-gray, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. ...

, to make

silver-gilt Silver-gilt or gilded/gilt silver, sometimes known in American English by the French language, French term vermeil, is silver (either pure or sterling silver, sterling) which has been gilding, gilded. Most large objects made in goldsmithing tha ...

. Traditionally, this technique is accomplished by first depleting a surface of

sterling silver Sterling silver is an alloy composed mass fraction (chemistry), by weight of 92.5% silver and 7.5% other metals, usually copper. The sterling silver silver standards, standard has a minimum millesimal fineness of 925. ''Fineness, Fine silver'' ...

to bring up a thin layer of

fine silver The fineness of a precious metal object (coin, bar, jewelry, etc.) represents the weight of ''fine metal'' therein, in proportion to the total weight which includes alloying base metals and any impurities. Alloy metals are added to increase hardn ...

. Then 24 carat gold foil is applied with heat and pressure— mechanical gilding—to produce a permanent

diffusion Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in Gibbs free energy or chemical p ...

bond. Pure precious metals such as gold and silver have a very similar

atomic structure Atoms are the basic particles of the chemical elements. An atom consists of a nucleus of protons and generally neutrons, surrounded by an electromagnetically bound swarm of electrons. The chemical elements are distinguished from each other b ...

and therefore have a good potential for bonding. Heating these metals to a temperature between 260–370°C increases the movement of the atoms. When pressure is added, this causes an electron exchange at the surface between the two metals, creating a permanent diffusion bond. This diffusion bond occurs far below the

soldering Soldering (; ) is a process of joining two metal surfaces together using a filler metal called solder. The soldering process involves heating the surfaces to be joined and melting the solder, which is then allowed to cool and solidify, creatin ...

temperature for either metal (Dhein, 2004). Examples of this technique have probably been observed, but not positively identified on pieces from the second half of the first millennium B.C. and from the early first millennium A.D. (Oddy, 1981). This technique is used in many cultures, including Chinese, Japanese and in the West to bond gold to other metals, including

iron Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...

copper Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...

aluminum Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...

, gold alloys, white gold,

palladium Palladium is a chemical element; it has symbol Pd and atomic number 46. It is a rare and lustrous silvery-white metal discovered in 1802 by the English chemist William Hyde Wollaston. He named it after the asteroid Pallas (formally 2 Pallas), ...

and

platinum Platinum is a chemical element; it has Symbol (chemistry), symbol Pt and atomic number 78. It is a density, dense, malleable, ductility, ductile, highly unreactive, precious metal, precious, silverish-white transition metal. Its name origina ...

. Foil made from gold alloys can be applied to silver and other metals by first

depletion gilding Depletion gilding is a method for producing a layer of nearly pure gold on an object made of gold alloy by removing the other metals from its surface. It is sometimes referred to as a "surface enrichment" process. Process Most gilding methods are ...

the surface of the foil (Lewton-Brain, 1987–1993).

References

*Dhein, Christine (2004).
Keum-Boo Pillow Pendant
* Oddy, Andrew (1981). "Gilding Through the Ages" *Lewton-Brain, Charles (1987–1993).
Keum-Boo

Traditional Arts Program Notes, 1998, Department of Anthropology, California Academy of Sciences. Artistic techniques Gold Metal plating Korean art Artworks in metal Hr:Nacrt:Keum-boo

See also

References