thumb| with a hawk and a sparrow, made by [[Hamano Masanobu, using the technique]]
is a Japanese metalworking procedure which produces a mixed-metal laminate with distinctive layered patterns; the term is also used to refer to the resulting laminate itself. The term translates closely to 'wood grain metal' or 'wood eye metal' and describes the way metal takes on the appearance of natural wood grain. fuses several layers of differently coloured precious metals together to form a sandwich of alloys called a "billet." The billet is then manipulated in such a way that a pattern resembling wood grain emerges over its surface. Numerous ways of working create diverse patterns. Once the metal has been rolled into a sheet or bar, several techniques are used to produce a range of effects.
has been used to create many artistic objects. Though the technique was first developed for production of decorative sword fittings, the craft is today mostly used in the production of jewelry and hollowware.
History
Origins
First developed in 17th-century Japan, was originally used for swords. As the customary Japanese sword stopped serving as a weapon and became largely a status symbol, a demand arose for elaborate decorative handles and sheaths.
To meet this demand, Denbei Shoami (1651–1728), a master metalworker from Akita prefecture, invented the process. He initially called his product , as the technique in its simplest form resembled , a type of carved lacquerwork with alternating layers of red and black. Other historical names for it were , , and .
The early components of were relatively soft metals and alloys (gold, copper, silver, , , and ) which would form liquid phase diffusion bonds with one another without completely melting. This was useful in the traditional techniques of fusing and soldering the layers together.
20th-21st century development
By the mid 20th century, had fallen into heavy obscurity. Japan's movement away from traditional craftwork, paired with the great difficulty of mastering , had brought artisans to the brink of extinction. It reached a point where only scholars and collectors of metalwork were aware of the technique. – that the craft was reignited in the public eye, as Hiroko and her husband Eugene Pijanowski brought the craft of back to the United States and began teaching it to their students.
Present day
Today, jewelry, flatware, hollowware, spinning tops and other artistic objects are made using .