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"Kashira made of dark-finished shibuichi, with gold highlights

Shibuichi (四分一) is an historically "Japanese alloy which can be "patinated into a range of subtle greys and muted shades of blue, green, and brown, through the use of "rokushō treatments.



Shibuichi means "one-fourth" in "Japanese, and indicates the standard formulation of one part "silver to three parts "copper, though this may be varied considerably according to the desired effect.


Aside from the basic 25% silver to 75% copper mix, combinations as divergent as 5% silver to 95% copper are also marketed as "shibuichi".[1] A wide range of colours can be achieved using the whole range of alloy compositions, even above 50% silver, e.g. 90% copper and 10% silver for a dark grey and down to 70% copper and 30% silver for lighter greys.[2]

Variation of Shibuichi[3]
name (JA) Ag : Cu, +Au[4] Note mentioned colors are after patination
Shibuichi 25 : 75 Dark grey, has a trace of gold
60 : 40, +1 Shiro is White in JA
lighter grey, harder, lower melting temp
40 : 60, +1 Ue is Upper in JA
Grey, harder
Nami-Shibuichi Uchi-Sanbu
30 : 70, +1 Nami is Regular in JA
lighter than Shibuichi
Nami-Shibuichi Soto-Sanbu
23 : 77, +1 Darker than Shibuichi

Kuro-Shibuichi (Kin-IchibuSashi)

Kuro is black in Japanese. Kuro-Shibuichi is different from others in the table. Kuro-Shibuichi is mixture of Shibuichi (40%) and "Shakudō (60%) with additional 1% of gold. The proportion is roughly 9.9% silver, 87.3% copper, and 2.8% gold. Kuro-Shibuich will develop black patina which is different from the black patina of Shakudo.

It is a common misconception that both copper and silver oxides form, but in fact a detailed study has shown that only copper oxides are formed on the copper rich regions of the material's microstructure, while the silver rich regions are left largely untouched.["citation needed]


The first official mention of the material is from the early 18th century, in documents from the State Mint, though it is believed to have existed before that. For most of its history, shibuichi was mostly used to ornament various fittings for "katana until the "Meiji reforms, when most swordmakers began to make purely decorative objects instead. The material is often used in "mokume-gane combinations. Similar alloys have been used elsewhere but the use of shibuichi to achieve different colored patinas appears to have remained nearly unknown outside Japan, until recent interest from artisans in the West.

Reverse of a "kozuka (showing the artist's signature) made out of intermediate gray-coloured shibuichi

See also[edit]


  1. ^ Art Jewelry Magazine, March, 2010.
  2. ^ Bradbury, F.W. (2012). "I Made That: Japanese Metalwork - Shibuichi". Retrieved 2012-05-06. 
  3. ^ GeoCities "Shibuichi" (JA) Retrieved 2012-9-1
  4. ^ Portion of Gold is added to Cu-Ag mixture
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