Monday, 13 June 2011

My new Raku Kiln

Here are some photos of my new 'Raku Kiln'. I cut and wired the frame together one day and then lined it the next. Now I am ready to go.





HOW I DID IT - The basic frame of the kiln was made using 2mm guage wire, which i bought on a roll from my local hardware shop (width of 600mm). I cut and wired the frame together with regular fencing wire. Once the frame was made, I partially lined the kiln with aluminium foil, then lined it with 1260c ceramic fibre blanket which I obtained from a refractory supply shop. It came on a 7.2m roll, 600mm wide and 25mm thick. It can be bought by the metre from most ceramic supply shops. I found that it was more econimical to buy it on a roll, plus I want to make other kilns, so why not. I used approx 4m of ceramic fibre and wire to make this kiln. I also used approx 4m of Kanthal Wire and 30 ceramic buttons which I made from raku clay. These were used to fasten the ceramic fibre blanket to the wire frame. In the photos, you will see a hole at the bottom where the gas burner will be placed and the hole at the top is the flue. The dimensions of these holes is quite crucial in order to achieve the required temperature and atmosphere within the kiln. I will know if I have to adjust these once I do my first firing. When firing, I will place the kiln on an base of bricks seperated by another layer of ceramic fibre to prevent heat transfer through to the bricks from the kiln.

HOW TO RAKU FIRE AND WHY?- Pots are glazed and placed in the kiln. They are then quickly fired/heated until they reach approx 950C to 1050c, depending on the maturing temperature of the glazes used on the pots. Once the required temp has been reached, they are then pulled from the kiln using long metal tongs and wearing heat resistant fire gloves as the pots are GLOWING and RED HOT. The time that the kiln takes to reach the required temp does vary from kiln to kiln and also depends on the operator, but generally I have pulled pots from the kiln within an hour and a half. The glowing pots are then placed into metal bins which contain a reduction material (for example newspaper, sawdust, leaves, straw). Once they ignite, a lid is placed on top of the bin to enclose and starve the pot of oxygen. A chemical reaction occurs within the glaze and clay body due to the heavy reduction atmosphere within the enclosed chamber. This process produces some wonderful effects on the clay and glaze. There are some beautiful glaze effects that can be achieved when firing in this way.

I love the whole process involved with Raku firing. It is very exciting, fast and a since it can be a little unpredictable, you never quite know exactly what you will get once you lift the lid of the reduction bin.

Examples of Raku.




Caution: Extreme care must be taken when handling the ceramic fibre blanket used to make such a kiln. Always take the advise of the manufacturer ie. wear appropriate mask and gloves. Also, when Raku Firing, you are handling red hot pots, kilns and equipment. Raku firing is very exciting and rewarding, but can be very dangerous! Great care and safety precations should be taken to prevent burns and accidents. Always use common sense, appropriate safety equipment and you will never have a problem. Always have a hose or buckets of water close by.  I would recommend, that if you are interested and considering raku firing, seek the advice of someone who has fired in this way before and ask to participate in a raku firing to best see how it all works. That is how I learned what I know.


2 comments:

  1. Have you fired your kiln yet? I'm building one. I think, maybe, horizontal is more efficient than vertical, especially because mostly, I'll do tea bowls. Thanks! Lee in Mpls.

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