About Raku
We often refer to certain pots as "Raku" pots and forget that the term does not mean
much to most people.
Raku, as a method of producing pottery, first appeared in Japan in the late sixteenth
century with the potter Chojiro. That process is quite different from the popular process of
firing that has evolved.
I won't go into all the history, though there are long explanations about the original
process and the reasons for the name. You can find out a lot more about it at this site.
(You may need to copy and paste into your browser)
www.lockettpots.uklinux.net/pottery/raku.php
For now, I just want to explain what makes Raku pottery different from high fired pottery
and why.
Glazed, high fired pottery is waterproof. When non toxic chemicals are used in the glaze,
the ware is suitable for food and liquid storage. Raku pottery is not high fired, waterproof,
nor is it suitable for foodstuffs. It will not stand up to freezing temperatures if used for
plants.
Earth Elements Art
earthelementsart@aol.com
earthelementsart@aol.com
First, let me give you a very brief explanation of how high fired pottery is handled. Clay is wheel thrown, or formed in
some manner and then bisque fired to about 1800 degrees. Then glazed is applied to the surface and the pottery is
re-fired at anywhere from 2190 degrees up to 2350 degrees or more. This process takes a very long time because
the bisque firing can take around 12 hours and the kiln has to cool for at least as long before the ware can be
removed and glazed. The ware must be absolutely dry when fired again, so a day or more is usually needed to dry
the clay after applying glaze. The high firing process takes even longer and has to cool as long. So you see, this
whole process can takes several days to complete.
some manner and then bisque fired to about 1800 degrees. Then glazed is applied to the surface and the pottery is
re-fired at anywhere from 2190 degrees up to 2350 degrees or more. This process takes a very long time because
the bisque firing can take around 12 hours and the kiln has to cool for at least as long before the ware can be
removed and glazed. The ware must be absolutely dry when fired again, so a day or more is usually needed to dry
the clay after applying glaze. The high firing process takes even longer and has to cool as long. So you see, this
whole process can takes several days to complete.
Raku firing is done much more rapidly and the results can be seen quickly. Once bisque fired, glazed, and
dried, the pieces are placed into a special Raku kiln. This has to be special, because the ware is removed
from the kiln while it is still glowing hot. Long tongs are specially made for this and care must be used with eye
protection, heavy gloves, and even a face mask to keep from inhaling the excessive heat.
Quickly, the piece is moved into a reduction chamber. (This is usually a trash can filled with combustible items
which can be paper, leaves, pine straw, etc.) More combustibles are added and when the whole thing is really
flaming up, the lid is put on tightly. The fire is starved of oxygen (reduction). After 20 to 30 minutes, the
chamber is opened and the piece is removed. At this point it will either be allowed to cool slowly or will be
dunked immediately into a tub of water to cool it. You can imagine that the immediate temperature change is
quite stressful to the pot and sometimes they blow out pieces, or just blow to pieces!
dried, the pieces are placed into a special Raku kiln. This has to be special, because the ware is removed
from the kiln while it is still glowing hot. Long tongs are specially made for this and care must be used with eye
protection, heavy gloves, and even a face mask to keep from inhaling the excessive heat.
Quickly, the piece is moved into a reduction chamber. (This is usually a trash can filled with combustible items
which can be paper, leaves, pine straw, etc.) More combustibles are added and when the whole thing is really
flaming up, the lid is put on tightly. The fire is starved of oxygen (reduction). After 20 to 30 minutes, the
chamber is opened and the piece is removed. At this point it will either be allowed to cool slowly or will be
dunked immediately into a tub of water to cool it. You can imagine that the immediate temperature change is
quite stressful to the pot and sometimes they blow out pieces, or just blow to pieces!
Okay, now your are asking yourself why anyone would be so crazy
to do this? Well, when the piece survives, the results can be
stunning, eye-catching, spectacular, and brilliant! And, even
though it is dirty and smelly, it can be a lot of fun.
Any portion of the pot that was not glazed takes on a charcoal gray
color. Glazed areas can range from a white crackle effect to
metallic hues, rainbow glows and just amazing colors.
Aside from the often fabulous results, it is a fun if messy process. It
should be done by at least 2 people and more just add to the fun.
Everyone stinks of smoking leaves and such, but sharing the
results means almost instant gratification for all involved.
These are the bottoms of two pots made with the same
kind of earthenware clay and unglazed. The left shows the
smoky gray color that is the result of a lack of oxygen
during the Raku firing. The right is the actual color of the
fired clay.
kind of earthenware clay and unglazed. The left shows the
smoky gray color that is the result of a lack of oxygen
during the Raku firing. The right is the actual color of the
fired clay.
This shows some of the really amazing results you can get
with Raku firing. This one has colors varying from metallic
yellow to red to blue, all from the same matte copper glaze.
The variations are actually made by the fire.
with Raku firing. This one has colors varying from metallic
yellow to red to blue, all from the same matte copper glaze.
The variations are actually made by the fire.
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