RAKU
ca: RAKU
es: RAKU
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Raku, is an oriental technic from the 16th century, it is believed to have been originated in Coria but it prospered in Japan and has extended throughout the world, apparently thanks to the tea ceremony. The word Raku means “happiness”. It is a method of creating effects with colors and textures with enamels or simply with smoke, rapidly fired and cooled while still in the oven. The clay used for Raku must be prepared with a high percentage of sand or grog to resist rapid changes at the extreme temperatures. A good choice of the clay to be used will avoid the risk of breakage.`
The firing of the enamels is done in gas or wood fired kilns. The enamels and colors are fired between 800 º and 1000 º C with rapid firing, reaching the right temperature in 15 to 30 minutes, then the kiln is opened and the pieces that are red with heat are taken out.
When a piece is taken out of the kiln and it is exposed to the air, it is put, for a short while, into a metal bucket, half full of sand or dry leaves, sufficient for the reduction of heat and smoke to penetrate into the piece and transform the colors, enhancing the crackled enamel due to the heat crash, which is quite common in this enamel technic. Next it is rapidly cooled down, for a short time in another bucket with water, washing out at the same time the smoke stuck to the enamel.
Besides the work done with classic enamel, brilliant and crackled, we also have the naked or lost enamel Raku technic, on which the engobe will not adapt itself to the holder making the enamel loose at the end of the process, and only the drawings produced by the smoke will remain, which can be induced by chance (crackled) or by the work of the ceramist.
There is also the technic known as “matt copper”, thanks to which with an over loaded copper enamel we manage to get a matt finish thanks to the wide color variety which copper develops in a reducing atmosphere.
The oven can be loaded from the top or at the front, although the most recommended is the one by which the body of the oven lifts, thanks to pulleys, and the pieces are left at the top easily workable. This procedure produces smoke, so it must be done in the open air. To get the pieces out of the oven you must use long pincers and protect yourself with spectacles and heat gloves.
Link to Author – Ramón Fort
Raku tongs are specially designed with long steel handles and legs. They are used to lift red-hot work out of the kiln and move it to the metal bucket of sand. The length allows you to hold it securely, far from your body and from the kiln, which emits very strong smoke and heat when opened.
Red is a strong color with many tones. There is a large selection of reds used in different types of decoration, which are fired at different temperatures. In the past it always had to be fired at a low temperature, between 700 and 800 Cº. This meant if working with colors fired at a higher temperature, the piece with red had to be fired a second time at a lower heat. In the last years this has changed, now it can be brought to use at different heats. 
The name of a restaurant made in flat relief, shown above, is made in twelve parts that form three sections and each one is decorated differently. 
Repeated tiles are designs on tiles made up to form a repeated pattern and the designs can be of one or more tiles put together to forms a continued design. 
Repoussé the dictionary explanation is: “A design raised in relief by hammering out on the reverse side.” It is a French word meaning “pushed up”. It also applies to a design in three dimensions but in reverse, inwards not outwards. When using clay, it can either built up or dug out so the design is inwards, but with marble it has to be carved out. 
Ribs are ceramic tools made of plastic, wood, metal and rubber and are used to smooth clay while turning with a wheel. They have this name because originally animal bones were used to make them. There are several sizes and two type ridge and flexible. 
Rolling pin is a cooking tool used for rolling out pastry and in ceramics, for rolling out clay. The clay is put between two walls or square poles of the same height. The height of the poles is the height you want your clay to be. Roll over the clay until the rolling pin rests on the walls, it will then be the height required. 
Roulette wheel wheel is a cube of wood or bisque made with a pattern notched into it. It can be of any size and be attached to a handle. When rolled over soft clay, the protruding parts are indented into the clay to create a pattern or texture. If you make a roulette wheel using clay, after creating the pattern, leave it to dry. When dry it can be used, but if it is to be used frequently fire it, as the dampness of the clay you will be working on will affect it. If a handle is required, build up the clay round a tube length-wise, so it goes through the middle. It should be big enough to pass a small pole of wood or metal through, which can then be attached to a handle. This makes it easier to roll and imprint.
Ruler is a strip of wood, metal or plastic with straight edges that are usually marked with whole and fractional units of length, inches, centimeters or both and used to draw straight lines and measure lengths. Rulers are made in different lengths, from ten centimeters to five meters and in one piece or many pieces hinged together to fold up. The illustrations show three types.