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 onto 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 gas kiln, an Anagama wood fired kiln
or an electric kiln. During the Crystallization week there is
also a second theme, an African fire.
Here’s a short summary of the main themes.
Originally an Anagama is a huge kiln from 600 BC in which one
year worth of pottery of 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 about 20 hours. The fire will lick the
pots and the ashes in the kiln will 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 gas
kiln to continue burning in a closed container. The thermic
shock causes little cracks, 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 organized 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.