Raku ware

Raku (Jap.楽 焼, rakuyaki ) is a special firing technique of ceramic bodies, which was developed in Japan. Furthermore, can be designated as the entire production process with Raku both the raw materials used for the production of glazes and raku ceramics.

- unglazed

History

Raku was developed during the Tenshō era (1573-1592) in Kyoto from the presumably non- Japanese- tile maker Chojiro (长 次郎) under the direction of the tea ceremony master, Sen no Rikyū. Chōjirōs students Jokei set forth later Toyotomi Hideyoshi's palace for the roof tiles jurakudai and thereby got a seal with the characters楽( raku, dt "Joy" ) awarded, which he accepted as a family name, and thus the pottery dynasty gave its name. In the Western world the traditional raku technique ( " Western Raku ") was modified by Paul Soldner and Bernard Leach and to his own style developed.

Technology

The glazed or unglazed vessel is - contrary to the conventional method to burn ceramic ( slow cooling in a closed oven ) - usually burned in the open air due to the thick smoke. In this low- fire, the red-hot vessels in a container of organic fuel ( leaves, straw, hay, etc.) are individually taken with a long forceps at temperatures around 1000 ° C the oven and embedded airtight. Raku pottery is often relatively thick walls so that they do not lose too much heat in this change from the furnace to the tank. The resulting smoke (carbon), oxygen deprivation, as well as the minerals contained in the leaves have a strong one on the potsherds and the glaze color. Leaf and grass footprints sometimes perpetuate itself in the soft glaze. Due to the strongly reducing atmosphere of soft glaze oxygen is removed. The chemical composition changes partially, eg of copper oxide (green), copper (red), and the glaze color changes. Carbon ( black) penetrates through fissures ( cracked ) and is deposited in a pottery shards. The combustion process can be controlled only at Raku, so each piece is unique and inimitable.

Raku - mass

Since the vessels must withstand strong shocks without prejudice temperature by the internal way, the Raku - mass is usually very coarse and contains a high proportion aplastic constituents, such as pumice, sand or grog. Many experiments and tests are necessary to obtain suitable shock-resistant and also plastic or fine clay mixtures. In addition, low lime content and additions of talc and lithium oxide having a positive effect, but this can also affect the plasticity.

Raku glazes

Raku glazes melt between 800 ° C and 1000 ° C ( low fire ). The glaze surface crack on cooling, causing the typical crackle is created. Coloring oxides are mostly iron and copper because of the strong color change. And metal salts are used.