At present, we in deKunstClub.nl are very much engaged in ceramics, what with the project "ceramics here and now" and the exhibition of the same name. One of the technologies that engages our warm interest is Raku-firing.
Wikipedia: Raku, a short introduction in Dutch
Wikipedia: Raku, an extensive description in English
We recently acquired a brand new propane gas-fired Raku kiln of quite nice proportions .... To inaugurate this great piece of equipment, we planned this first dedicated Raku event.
We invite everyone who wants to join in this event to create a Raku-work. We will then in one combined sunday session fire these works, one by one, in the proper Raku fashion. In the morning you glaze your work; in the afternoon it will be fired, reduced and cleaned. The finished works will be exhibited in deKunstClub.nl for a short time, after which they will be collected by the makers.
Raku firing is a spectacular happening. The workpiece is glazed with a special lead glaze, dried and then put in the kiln. Here it is heated in roughly one hour to a temperature of about 1,000 degrees Celsius. At that temperature, the glaze is molten and covers the clay body. Upon reaching that state, the work is lifted out of the kiln with long tongs - vivid red hot and radiating quite a bit of heat.
In the open air, the piece starts to cool very quickly. The glaze solidifies and, since it is not free to shrink as it should, it crazes. You actually hear cracks in the glaze develop. The so-called craquelé is a special characteristic of Raku work. When the cracking is sufficiently advanced, after perhaps a minute, the work is placed on a heap of combustible material, such as sawdust, shredded newsprint or similar. This stuff immediately catches fire. Quickly a metal container is placed over the work, completely isolating it from the air. The fire cannot continue, due to lack of oxygen, but it starts to smolder, developing a thick black smoke in the container. This is the so-called "reduction" stage. The black smoke and soot enter through the cracks in the glaze and colour the clay body intensely black in the typical Raku crack-pattern. Any clay area not covered by glaze will be an indelible uniform black after the reduction.
After say half an hour of reduction the piece is taken from the container, cooled down and then cleaned by brushing it with water. This develops the final appearance of the work.
The results of a Raku firing are usually quite unpredictable - which precisely is the fun of this technique. Sometimes very beautiful pieces "just happen".
A very active and exciting way of making art! Do you want to join in this event? You can - just register with Alex. It is as always free.
foto ontleend aan de Wikipedia
Some practical considerations.
If you want to join in this event, Alex can give you the technical information you need to make a work suitable for this event (best-suited type of clay, maximum dimensions etc, etc.).
sunday december 9
This day we will run a working day dedicated to creating your Raku-work in clay. There will be two types of suitable clay available (chamotte / silversand) and we will give instructions about maximum size, preferred wall thickness, uniformity of same, available glazes etc. A wide variety of tools is also available.
saturday december 29
The actual Raku-event. In the morning you can glaze your work. It has to dry, of course. Meanwhile, you can prepare your reduction medium. We will discuss various options, such as sawdust, shredded paper of all kinds, fragments of (natural) textiles, dried leaves, twigs, toilet paper, oil-impregnated tissue paper, hair cuttings, .... whatever you can think of (as long as it is deemed suitable). You do the preparation yourself. After lunch, the kiln will be started and the firing can begin. Work after work will be fired, cooled, reduced. It is expected that the first work requires about an hour to reach 1,000 degrees and each subsequent work about half an hour. Smaller works may be combined in the kiln. This may cause a bit of nervous hassle, though ....
In between these two dates, Alex will take care of thoroughly drying the works and he will further biscuit-fire them to 900 degrees Celsius. This to reduce the risk if breaking work due to over-quick heating.
Preparing your Raku work under your own steam?
Is of course also possible. Follow these specifications.
Suitable raw material
- special Raku clay
- clay with 30-40% chamotte of at least 0-1 mm grain
- clay with at least 20% silversand
- (when you biscuit-fire yourself) max. 40 cm wide, max. 50 cm high
- (if you want it bisccuit-fired here) max. 30 cm wide, max. 40 cm high (do remember that an unfired clay work of this size is quite fragile!)
- as uniform as possible, thin walled, up to a max. of 10 mm
- all Raku glazes, preferable with Pehatine to bind lead dust
- if you want to use metal oxides (very toxic) make sure to use Pehatine and tell us exactly what you have been doing (!)
During these days bring food and drink to your own discretion - lunch will be a communal meal. After careful washing of the hands! Lead glaze IS toxic!