Raku-Technique Zoubair Selimi

The raku technique is a special firing technique developed in Japan in the 16th century. The term "raku" means joy, satisfaction and pleasure. By the special interaction of the four basic elements fire, water, air and earth the technique of the raku firing reminds us of  the transformation in alchemistic processes.

In contrast to the conventional process of firing ceramics by slow cooling in the kiln, in raku firing the work pieces are heated in a short time to approx. 1000 ° C in the kiln and then removed with tongs in the glowing state. As soon as the work pieces have been unloaded, the large temperature difference between the kiln and the outside air causes a corresponding thermal shock.

To cool  down the ceramic, it is often enclosed in an airtight container with organic fuels such as leaves, hay or wood chips. So that the ceramic does not lose too much heat during this change, the work piece is relatively thick-walled. Since a large amount of smoke is generated during this process, the ceramics  are usually fired outdoors. The firing process can only be influenced to a limited extent with the raku technique, so that each piece is an original. By using coloring oxides, mostly iron and copper oxides, the metallized colors are created on the surface of the ceramic.

The airtight cooling process removes oxygen from both the clay and the glaze, which changes the chemical composition and can lead to color changes in the glaze. The large temperature difference can also cause cracks in the surface in which carbon is deposited and these cracks then turn black.

In the studio Zoubair Selimi the ceramics are treated in a slightly modified process.  In order to cool down the pieces quickly, they are dipped in water, always with the risk of cracking. In glazed work pieces, the enormous temperature difference in the glaze causes cracks: the typical craquelé effect of the raku technique.

All ceramics were designed by Alexander Schwarz and formed and modeled on a clay plate. Each work piece consists of several parts that are mounted on a plate after firing. The 20 ceramics shown here from the Atelier Zoubair Selimi were produced in a limited edition of 8 copies.

Raku-Technique Bella Terra

Also in the studio Bella Terra most of the ceramics were made in raku technique. Some of the bas-reliefs in raku technique or glaze firing are mixed techniques, to which metallic materials have been added when modeling the still wet clay. The process of ceramic production begins with the shaping and drying of the clay.

After a first, so-called bisque firing at temperatures up to 950 ° C,  which gives the clay the necessary stability, the glaze firing is carried out at low temperatures in a second firing process. For some ceramics, the gold leaf technique was added after cooling of the glaze firing.

Other bas-reliefs were made in the technique of pit-firing. Pit Firing is the oldest known method for burning ceramics. It was created almost 30,000 years ago. Pit firing is an atmospheric process. For this technique 3 firings are necessary: one for the bisque, the second for the glaze and the third for the sulfides.

This third firing with oxides and sulfides is done in another kiln. When the pieces are hot enough to open their pores, the colored vapor penetrates the pores and sticks there. All colors and patterns of the ceramic derive from this atmospheric process.