All objects are fired twice. The first time the raw clay is
baked and it becomes biscuit. The pot is then hard but still
porous (like flowerpots). After the first firing a thin layer of
quarts with metal oxides is put on the pot. The object is then
fired for the second time. Depending on the theme of the week
that will be done in a Raku gaz kiln, an Anagama wood fired kiln
or an electric kiln. Apart from the main theme of the week there
is always a second theme, like a pitfire or Terre Vernissée.
Here’s a short summary on the main themes.
Originally an Anagama is a huge kiln from 600 BC in which one
year worth of pottery made by a Japanese potter was fired. These
kilns were fired with lots and lots of wood. Our miniature
Anagama is a smaller one in which 1.5 cubic m of wood reaches
the right temperature in 15 hours. The fire that licks the pots
and the ashes in the kiln vitrify and stain the clay. A very
primitive but charming way of firing!
In Raku-firing the red hot objects will be taken from the
ceramic kiln to continue burning in a closed container. The
thermic shock causes little cracks to form, the craquelé that
makes every object unique. Raku is a traditional Japanese
technique from 1600 BC.
For Crystalline glazes a recipe with a lot of zinc-oxide is
used. This glazing is melted on the object in an electric kiln
at a temperature of 1275 degrees centigrade. Objects stay in the
kiln for 30 hours, in a special atmosphere and under specific
conditions concerning the viscosity. This makes the crystals
grow. Every object is unique and has its own special crystals
and colours. The prisms of the crystals are best seen in intense
light. (Weather permitting a pitfire will be organised as a 2nd
theme during this week.)
With this technique the pots are not glazed, but polished with
slip before the firing. After which they will be fired the
primitive way, in an enormous campfire. After the firing the
pots will be polished once more with bees wax.