The Raku Firing Process
Raku History.
Raku is Japanese and translates literally as "ease" or "enjoyment" and comes from Jurakudai, the name of a place in Kyoto, Japan.
Story has it that sometime in 16th century Japan, a Tea Master who was involved with the construction of Jurakudai, had a tile-maker named Chōjirō the he charged with the task of producing tea bowls that were to be used in a specific style of tea ceremony called "wabi" that was one of the Tea Master's ideal presentations. The hand-molded tea bowls that Chōjirō presented as his final product earned him a degree of recognition. The Tea Master initially called it contemporary ware or "ima-yaki". Sometimes these wares were called "Juraku-yaki" because the red clay that was used in their creation was called Juraku clay.
As a result of Chōjirō's craftsmanship, he was presented with a seal that had the Japanese character for Raku on it. These wares were the first in Japan to be produced bearing a seal of craftsmanship. It was from this point on that Raku would be the name of the family that produced this type of ceramics. Japanese clay art has been heavily influenced over the centuries by the Raku family and their style of ceramic production. The family is now in its 15th generation.
Raku is a three step firing process where the pieces don't always make it through the entire firing process. Sometimes the pieces don't finish to have the desired colors or crackled appearance that is characteristic of the Raku technique. Actually, the pieces sometimes end up as pieces in the bottom of the kiln or reduction chamber as they can tend to fracture and break due to thermal shock. Western artists combat this problem by adding Kyanite to their clay which helps strengthen the body and reduces the clay's level of thermal expansion.
The first part of the firing process is one that most artists are familiar with and is called a bisque firing. This is the part of the process that hardens the clay and makes it possible to apply glazes and other artistic touches.
An excellent example of Raku
The next part of the firing process is glazing done in a kiln with temperatures of around 1800 degrees give or take 50-100 degrees. The pieces are allowed to come up to the desired temperature and then they are transferred to a "reduction chamber", the third part of the process. This chamber is usually a aluminum trash can and once the pieces are placed inside the artist then adds a carbon rich material such as dried grasses, straw, or sawdust. Some use newspaper which ignites immediately. The lid is placed on top of the trash can. The fire will reduce the amount of oxygen in the can drawing the oxygen out of the glaze and the clay forcing the clay pieces to pick up the carbon from the oxidized materials.
The blackness around the cracks is result of the clay and/glaze picking up the carbon at the site of the crack. This effect is characteristic of the raku process. The swirling and presence of the different colors on the finished pieces is caused by the open flames and the varying temperatures in the trash can or firing chamber.
Raku enthusiasts take very good care of their collections. These pieces are seemingly more fragile than other types of ceramics. Don't fret though if you are a novice, care of your Raku ceramics is simple: first and foremost remember that these pieces are porous and are not meant for use like traditional pottery. Modern Raku is meant for aesthicsclean with a lightly dampened cloth and brush to remove dust. Also, avoid displaying your pottery in direct sunlight as the UV rays may alter their coloration.
