Raku is a pottery technique that has it's origins in 16th century Japan.
We are pretty sure that it was developed by Korean potters under Japanese
rule but the exact circumstances of it's development and in what context it
was discovered is a mystery.
The raku technique, like other pottery techniques such as salt glazing and
pit firing, primarily revolves around it's firing process although involvement
with raku often goes much deeper into its philosophy, roots, and cultural
significance. Traditional raku and our western version of raku are similar
in many ways though there are some significant differences.
To briefly describe the raku process we must understand that most all other
types of pottery are loaded into a cold kiln where the firing proceeds slowly
until the desired temperature is reached. This firing cycle may take anywhere
from 8-24 hours or even longer. When the kiln has reached temperature (which
is generally determined through the use of pyrometric cones), it is shut off
and allowed to cool enough to be able to remove the ware using bare, or lightly
gloved hands. The cooling cycle may last from 12-24 hours or longer.
The ware is considered finished when it is taken from the kiln. In raku, the
pieces may be loaded into a cold kiln but are often preheated and loaded into
a hot kiln. The firing proceeds at a rapid pace with the wares reaching temperature
in as short a cycle as 15-20 minutes (though raku firings can last up to several
hours depending on the individual pieces and their firing requirements).
Glaze maturity is judged by the trained eye without the use of cones or measuring
devices. When the firing is determined to be completed the wares are immediately
removed from the kiln. Since at this point the glaze is molten, tongs or other
lifting devices are used.
This is the stage in the process where traditional and contemporary raku differ
in technique and treatment. In our western version the wares are now treated
to a 'post firing reduction' phase. The wares are put into a container with
combustible material such as sawdust, or leaves and allowed to smoke for a
predetermined length of time. The carbonaceous atmosphere reacts and affects
the glazes and clay and imparts unique effects and surfaces to the wares.
Some of these effects are metallic and crackled glazes surfaces and black
unglazed clay. When the wares have cooled, they are washed with an abrasive
cleaner to remove all residue of soot and ash.
