View source for Chemistry:Keum-boo

[[File:Keum-boo ring blackened.jpg|thumb|Silver ring gilded with 0,4 mm gold with the keum-boo technique, hammered and blackened]]
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{{Infobox Korean name
| hangul = 금부
| mr     = Kŭmbu
| rr     = Geumbu
}}
'''''Keum-boo''''' (also ''Geumbu'', ''Kum-Boo'' or ''Kum-bu''—[[Social:Korean language|Korean]] "attached gold") is an ancient [[Place:Korea|Korea]]n [[Chemistry:Gilding|gilding]] technique used to apply thin sheets of [[Chemistry:Gold|gold]] to [[Chemistry:Silver|silver]], to make [[Chemistry:Silver-gilt|silver-gilt]]. Traditionally, this technique is accomplished by first [[Engineering:Depletion gilding#Variations|depleting]] a surface of [[Chemistry:Sterling silver|sterling silver]] to bring up a thin layer of [[Millesimal fineness#Silver|fine silver]]. Then [[Millesimal fineness#Gold|24 carat]] [[Chemistry:Metal leaf|gold foil]] is applied with heat and pressure—[[Chemistry:Gilding#Mechanical gilding|mechanical gilding]]—to produce a permanent [[Physics:Diffusion|diffusion]] bond. 

Pure precious metals such as gold and silver have a very similar atomic structure 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 [[Engineering:Brazing|soldering]] 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 [[Chemistry:Iron|iron]], [[Chemistry:Copper|copper]], [[Chemistry:Aluminum|aluminum]], gold alloys, white gold, [[Chemistry:Palladium|palladium]] and [[Chemistry:Platinum|platinum]]. Foil made from gold alloys can be applied to silver and other metals by first [[Engineering:Depletion gilding|depletion gilding]] the surface of the foil (Lewton-Brain, 1987–1993).

==See also==
* Art movement
* [[Creativity techniques]]
* [[Chemistry:List of art media|List of art media]]
* List of artistic media
* List of art movements
* List of most expensive paintings
* List of most expensive sculptures
* List of art techniques
* List of sculptors

==References==
*Dhein, Christine (2004). "[http://www.jewelryartistmagazine.com/stepbystep/aug04.cfm Keum-Boo Pillow Pendant]"
*Oddy, Andrew (1981). "Gilding Through the Ages"
*Lewton-Brain, Charles (1987–1993). "[http://www.ganoksin.com/borisat/nenam/keumboo.htm Keum-Boo]"
*[https://web.archive.org/web/20070204082632/http://calacademy.org/research/anthropology/tap/archive/1998/1998-11--kumboo.html Korean Kum-Boo Metalwork], Traditional Arts Program Notes, 1998, Department of Anthropology, California Academy of Sciences.

[[Category:Gold]]
[[Category:Metal plating]]

{{Sourceattribution|Keum-boo}}