Raku pottery
Raku ( Japanese 楽 焼 , rakuyaki ) is a special firing technique for ceramic masses that was developed in Japan . Furthermore, raku can be used to describe both the raw materials and glazes used to produce the raku ceramic as the entire manufacturing process.
| Class: Earthenware | Subclass: other earthenware | Group: Pottery | - glazed - unglazed |
history
Raku was developed during the Tenshō era (1573–1592) in Kyoto by the roof tile maker Chōjirō ( 長 次郎 ), presumably of non-Japanese origin, under the direction of the tea ceremony master Sen no Rikyū . Chōjirō's student Jōkei later made the roof tiles for Toyotomi Hideyoshi's palace Jurakudai and was thus awarded a seal with the character 楽 ( raku , dt. "Joy"), which he adopted as a family name and thus gave the pottery dynasty its name. In the western world , the traditional raku technique was modified by Paul Soldner and Bernard Leach and developed into a style of their own ("western raku").
technology
The glazed or unglazed, prefired usually after Asian example at about 700 ° C geschrühte vessel - to burn contrary to the conventional method ceramics (slow heating up and cooling down in the closed furnace) - used in the already highly heated oven and glowing removed and strong due to the Smoke development mostly burned outdoors. With this low fire, the red-hot vessels are individually removed from the furnace with long pliers at temperatures around 1000 ° C and embedded in a container with organic fuel (leaves, straw, hay, etc.) in an airtight manner. Raku pottery is often relatively thick-walled so that it does not lose too much heat when moving from the oven to the container. The resulting smoke (carbon), the deprivation of oxygen and the minerals contained in the leaves have a strong effect on the pottery shards and the glaze color. Leaf and grass prints are sometimes immortalized in the still soft glaze. The strongly reducing atmosphere removes oxygen from the still soft glaze. The chemical composition changes partially, e.g. B. copper oxide (green) becomes copper (red) and the glaze color changes. Carbon (black) penetrates through hairline cracks (cracks) and is deposited in the pottery shards. The firing process can only be controlled to a limited extent with the raku, so that each piece is inimitable unique.
Raku mass
Since the vessels have to withstand strong temperature shocks due to the way they are fired, the raku mass is usually very coarse and contains a high proportion of non-plastic components such as pumice , sand or chamotte . Many experiments and attempts are necessary to obtain suitable shock-resistant and also plastic or fine clay mixtures. In addition, a low lime content and the addition of talc and lithium oxide have a positive effect , which can, however, also affect the plasticity.
Raku glazes
Raku glazes melt between 800 ° C and 1000 ° C (low fire). The glaze surface cracks when it cools, which creates the typical crackle . Coloring oxides are mostly iron oxide and copper oxide because of the strong color change. Other oxides and metal salts are also used.
literature
- Morgan Pitelka: Handmade Culture: Raku Potters, Patrons, and Tea Practitioners in Japan , University of Hawaii Press, 2005. ISBN 978-0824828851
- Bernard Leach: Das Töpferbuch , original title: A Potter's Book, Hörnemann Verlag, Bonn-Röttgen 1971. ISBN 3 87384 406 0
Individual evidence
- ↑ Raku ceramic manufacturing process in pictures
- ↑ Bernard Leach . Biography (English).
- ↑ History and origin of the raku technique Page with a brief historical outline.
- ↑ Das Töpferbuch, Bernard Leach, p. 263
