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Wood fire

Posted on May 1, 2013 by in Pottery Blog | 0 comments

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small-pot bottle bottle-2 potWood fire

Wood firing is getting back to basics for a potter and returning to the origins of pottery before the use of gas, coal, oil and electricity. It involves the gathering and drying of wood which means quite a big lead time before a kiln can be fired, then there is the ongoing collection so that a constant source of dry ready fuel is there to use. There is the issue of having space to store the wood and the energy to cut it all up. So in all, it entails a great deal more effort and time than the fuel sources readily available to potters these days.

My reasons for trying wood fire are complicated and many. I have specialized in porcelain that responds better to clean fuel such as gas or electricity, but have always had a love of the effects available to wood firing resulting from the natural ash glaze resulting from the wood used to fire the kiln. Also, as a potter I love the much rougher clays that lend themselves more to the fire blushes and effects of a wood kiln.

In recent years I have also been helping out in a project to assist Villagers in Vanuatu relearn the skills of making pottery, and in their circumstance they only have wood available as a fuel, which has been the tipping point to encourage me to build and fire a wood kiln to learn these skills that many western potters have lost or avoid because of the easy availability of other fuel.

Lastly, there is the cost of firing. Gas is becoming increasingly expensive as it electricity and by comparison wood is still very economic so long as you forget the effort involved in collecting and drying etc.

I have had the opportunity to fire a friends two chambered climbing kiln occasionally in the last ten years or so which has encouraged me to consider building my own. After some research where I was drawn firstly to fast fire wood kilns, I settled on a Steve Harrison designed bourry fire box kiln, and proceeded to build this kiln with bricks that I had collected from an assortment of kilns over the years. While somewhat slow, it is a very satisfying thing to build a kiln that will achieve 1300 degrees Celsius using wood as a fuel.

 

I spent a few weeks making suitable wood firing pots, biscuit fired them and then using a variety of glazes including tenmoku, shino, rutile glazes, prepared the kiln for firing. This kiln also has a “throat” section after the firebox where pots can be placed unglazed and expect to be naturally glazed, just from the ash from the firebox, so in effect I have two kilns in one that produces different effects depending on where you place the pots and whether you glaze them or not.

The firing itself was over two days. The first day I lit a small fire in the base of the firing chamber and kept it burning low so as to warm the kiln and the pots. I used old redgum sleepers to keep in ticking over during the night and in the morning the temperature was up around 200 degrees. The main firing itself went relatively smoothly though at one stage I seemed to get stuck on 1050 for a couple of hours before I realized that I needed to pull the damper shelf wide open in the chimney and let the kiln do its thing. After this it took off and I got up to cone 11 (just over 1300) going down around 10.30 in the evening. After leaving the kiln for close to two days to cool, I had the great pleasure of opening the chambers to see the results which for a first firing, surpassed my expectations. I look forward to more firing and  varying results in the near future. Wood firing changes the pots in ways that cannot be achiever in a gas kiln. The pots had a quality that is unique to a wood kiln and I find quite exciting. I can well understand the reason why potters who fire by wood get hooked on this type of kiln.