We have just fired the 5th incarnation of our little, portable, stoneware capable, wood fired kiln. It fired very well, again easily in 3 hours. It just cruises along at its own pace. 1 hr to 1000 oC and then 2 hrs to 2 1/2 hrs in reduction to stoneware cone 10 over.
This variation was to test out the new chimney arrangement and that worked perfectly, some much better than the previous one. I am very happy with that. Another problem solved!
The hard-working firing team, going at it flat out. Half way through the wood stack in the barrow. Going for the big final effort, no holes barred! Go for it ladies!
I have it adjusted now so that as the temperature reaches 1000 oC. The kiln automatically goes into reduction. I don’t have to use a damper to make this happen. The kiln continues to rise steadily over the next two hours without having to alter any settings in the firebox. It’s lovely.
However, I notice slight difference in the fired surfaces around the setting, so I conceive of another experiment to try and even out this anomaly. I have everything that I need in stock in the spare parts shelf in the pottery, so no need to go out and buy anything. I spend the morning cutting, grinding and painting all the new bits and the kiln is primed and ready to fire again. I need to glaze some more work for this firing, so there will be a days delay while they dry out. This will be variation/refinement firing number 6.
I’ve learnt from bitter experience that if I fire fast with freshly applied glazes. I can blow them off the pot on the underneath side. All my bodies and glazes are currently made here onsite from locally collected and processed rocks, shales and ashes. Everything is made onsite and it takes a month of Sundays to get it all organised, dried, crushed and milled and then bagged ready for inclusion in the glazes. These are weighed out and then sometimes re-milled. and at other times, just passed through a very fine sieve to extract any small detritus that was caught in a gap around the lid of the ball mill and didn’t get fully ground. Glazes with no clay in them are notoriously delicate and friable to handle once dry and very prone to just falling off from the underneath side of pots. Of course i use a little bentonite to help stabilise them and shrink them on as well as creating a little bit of dry strength, but I have found that I can only add 1 or 2 % before it starts to change some of the glazes.
Tragically, as always seems to happen. I found yet one more issue with this configuration that needs a little more thought. During this last firing, I notice that I could improve the kiln shelf and stainless steel grating arrangement. So it’s back to the drawing board, or in this case, the work bench and I make a new set of one-piece ceramic supports that I hope will work a lot better. I pull the kiln to pieces and start again from scratch, right back to floor level and create a new setting design.
Maybe this will be the last of the beta firings?
We will fire again today with a load of Janine’s work in it this time. As she has a load glazed and dried ready to go.
Always so much more to learn.