New Small Wood Fired Kiln

The first of the figs are ripe and we savour it. It is just perfect, sweet and juicy. We wouldn’t have got it or any others if The Lovely Hardworking One, hadn’t been out there early and netted the branch a few weeks ago. If we don’t net the fruit trees or the most laden branches, the birds take everything.

There weren’t any fruit eating birds here in this bushy area when we arrived, but 40 years on and an enormous amount of work later, we have built 4 dams for a secure key-line water supply and open grassy areas between the orchards, with areas of understory native shrubbery. We left all the really big established trees and without knowing it, we created a perfect habitat for all sorts of native bird life, from the very small finches, through to bowerbirds and magpies. There is even a very large white owl, that we haven’t managed to see close-up, so we can’t identify it. It has taken frogs off the kitchen window at night, right in front of our eyes, but moves so quickly and so totally silently that it strikes and removes its prey, without actually touching the glass and is them gone is a flash of pale wings, before we can adjust our eyes to the scene. I’m constantly amazed at how clever our birds are at fossicking out a living from our little property. So the fruit trees have to be enclosed to protect some of the fruit for us. The vegetable garden is now totally enclosed in small (35mm.) hex gal wire and very fine nylon mesh. This keeps out most of the birds that we don’t want in there. Those are the fruit and veg eaters, but allows the little finches in to feed on bugs. It seems to work OK for us now, but has taken a lot of trial and error to work it all out – mostly error.


I have spent a little time over the summer break building another version of my portable stoneware wood fired kiln. These kilns are a direct response to seeing and working with Stefan Jakob’s ‘Ikea’ garbage bin raku kilns. Such a fun idea! And they work really well too, but only at the lower temperatures used for raku. It made me think about if it would be possible to make a reliable stoneware version of this kiln. Not in an Ikea bin, but in a custom made stainless steel monocoque box frame. The answer that I have been developing over the last half dozen years in my spare time is Yes!

This one solves all the problems identified in the last version, that although it could get to stoneware, some of its components weren’t likely to have a long life. I abandoned the ceramic fibre lining, as it doesn’t last for extended periods of time at very high temperatures where there is a lot of wood ash. The fibre turns glassy and peels off, like glaze shelling off, exposing new fibre, which then dissolves, the ash glaze slowly eats its way through the lining in this way.

We first experimented with a ceramic fibre lined stoneware wood fired kiln back in the late 70’s and early 80’s (see Handbook for Australian Potters P289-291.) In that kiln I used the new material at that time called ‘saffil’ board, that was mostly composed of alumina fibre. A 10 mm. hot face lining of this material lasted 30 stoneware firings before it was eaten away in the hottest part. These new little kilns use light weight refractory insulating bricks as the lining.

I couldn’t allow myself to recommend or to sell anything that wasn’t up to scratch and capable of delivering a long working life, so the development has continued, designing out the apparent flaws as they made them selves known. So now the design is a little closer to completion. I have designed version 5, so I hope that after that is built and fired a few times, everything will be settled down and we will have a very long lived and reliable small portable kiln. I think that we could say that we are now moving from prototype to beta testing stage. Perhap there will be something that we can sell to other potters with like minds. Just like we do with the more substantial gas and electric kilns that we build here – only much cheaper.

The improvements in version 4 meant that we could fire it up to 1,000oC in one hour. This part of the firing could easily go very much faster, but we have cracked kiln shelves in the past by going too fast below red heat. We then took the firing from 1000 to 1280 in another hour, finally soaking at 1280oC to 1300oC for the last hour until cone 10 was over. We got very good reduction colour in the glazes in that time frame. I was amazed what a couple of extra hours could achieve, in terms of quality. After all it’s not all about intense speed. We can already do that. This is more about getting very good quality results with a minimum of expenditure of effort and fuel.

I spent a few days working out how to create this little wonder of a kiln, to enlarge it to use a 12” x 18”  (300mm. x 460mm.) kiln shelf in the setting, and still be able to cut the frame out of one sheet of Stainless steel with no or minimal wastage.

I’m sure that there are a number of potters who are with me and like minded in this regard, potters who are thinking just the same as me. How can I achieve lovely wood fired results without firing for days and creating loads of smokey pollution. I think that this sort of little fun kiln will be very good for potters with an interest in wood firing, but without the large work flow required to fill a larger anagama kiln, or a suitabe place where so much smoke can be created day after day. This little kiln is definately not smoke free, but the smoke is minimal.

As it turned out, this was a very relaxed and easy firing using dead brushwood and small, dead, fallen branches as fuel. There are always loads of eucalypt paddock falls all around our property from season to season. We collected 3 wheel barrow loads, one of kindling twigs and another two barrow loads of small thin branches, up to 50 mm in dia. We ended up using only 2 of them. We will fire it again for a little longer next time, slowing it down a little so that we can not only get the good reduction colour in the glazes but also some surface flashing in the bodies as well. I’m intrigued, what is the minimum length of firing time required to be able to get some pleasing wood fired effects on the surface of our pots?

When we fired up my pots in the first kiln, up to stoneware in just 1 hr. in reduction in the earliest version of this kiln, there was little reduction effect showing in the glazes. The pots looked pasty and palid, as if oxydised, but were in fact very pale grey, so they were reduced. It seemed that 30 minutes of reduction wasn’t enough to get a good response from the clay and glaze chemistry. This time, at 3 hrs. The results have shown very good reduced glaze colour effects, but only a very limited flashing colour on the exposed clay bodies. The work is starting to show some pink flash on the porcelain clay bodies with this slightly longer firing time, so we are getting close now. At least there is something there. The difference between one hour and 3 hours is dramatic. Perhaps the next firing of 4 or 5 hrs to S/W will do the trick and give results that I am better pleased with?

I want every thing now! I just don’t have the time to be able to do it all.

best wishes

from the multi-tasking S&J