Two questions I'm seeking answers to at the moment:
- is it feasible to build a mini wood-fired kiln?
- if so, what is the highest temperature it could be fired to?
I'm exploring the possibility of designing a very small kiln for use in a suburban environment, so ideally it has to produce no more smoke than a household barbecue. Last week I created a simple up-draft prototype using normal house bricks to build a firebox and a kiln chamber and chimney made from cylinders of kiln fibre. The chamber was large enough for around nine small-to-medium pots placed on two layers of shelving.
The kiln was stoked with charcoal and wood for around five and a half hours (that is to say, until I ran out of fuel!) and temperatures in the firebox were high enough to make the metal grill slump. The 5-inch high ember pile turned pale yellow and the flames a beautiful lavender-blue.
I was hoping to get to high earthenware temperature in the chamber, but we didn't get there...even cone 05 didn't go down, but the temperature was high enough to sinter the fen slip I'd applied as a glaze to the inside of a few of the pieces. By the end, the kiln fibre was glowing a bright orange and you could watch waves of flames surging up the walls of the chamber..it was worth five hours' hard labour just to see that.
One thing I was pleased about was the low level of smoke produced..generally, the fuel burned very efficiently and smoke only became evident when a damper was placed over the top of the chimney. Once things got toasty in the chamber, seven inch flames would shoot from the chimney as wood was piled on..pretty impressive for a kiln less than five feet tall!
This design was just cobbled together using stuff I had lying around..next time I plan to build one using H.T.I. bricks and a second layer of one-inch kiln fibre. I will also reduce the height of the kiln chamber and make the chimney taller...hopefully that will make much higher temperatures achievable.
I've yet to find much on the web about mini wood-fired kilns. If anyone has any ideas or links, I'd be glad to hear about them. I do remember a chap demonstrating a tiny, portable kiln at a ceramics fair back in 2007. It was fired with charcoal, and he reckoned it could reach stoneware temperature. The chamber was miniscule though, as were the pots he put in there.