Mayhem

Last week's experimental firing of the restored kiln was a bit hairy,to say the least. The kiln was firing very unevenly- over 100 degrees hotter at the top,and I noticed that my new arch was starting to sag suspiciously towards the back- the hottest part. In addition,small flames were licking out of sundry unplugged gaps,and the gas tanks were freezing over. Cone 7 was just starting to bend on the bottom when I finished the firing [cone 9 down on the top] and I went to bed not a happy potter.
The next morning [the kiln cooled down very quickly,another problem] I unloaded the kiln- in the end,not a bad firing,with only the bottom shelf too cold,some nice reds,and the reduction only a bit too weak [I had to block off the chimney completely to get a good reducing flame]. But the arch had indeed sagged,as you can see,which is what I had been afraid would happen. It seemed that the experiment [building the arch from laminated arch sections of ceramic fibre board] had failed,so I started phoning around to see what a new gas kiln would cost me. Laser [London,makers of my current kiln] are on holiday for the foreseeable future,but I estimate that the same model would set me back around 35000 shekels. They now build a modular brick version which is even more expensive. Abraham Kilns said that they would build me a [brick] kiln for 45000 [they build good electric kilns,and have built a couple of bigger gas kilns]. Then I called Minerals and Refractories to ask about kiln materials,and while talking to them,it suddenly dawned on me that I must have used the wrong grade of ceramic board: all the signs were there [excessive shrinkage,brown discoloration,and other arch sections from a separate batch that didn't sag at all or shrink much] but I'd been too attached to my own reading of the outcome to notice them. This realisation came as a considerable relief,maybe postponing the inevitability of a new kiln for a while- at least for another firing.It's amazing how defenceless I felt without a working gas-kiln! I scrounged some ceramic fibre blanket [from Sydney,of course] and,having patched,propped and stuffed all morning,loaded the kiln and started a late firing just before 4 in the afternoon. We're now up in the 800's,and anything goes.
You can see the fallen arches at the back;yes,a section of roof was sitting on that one cup. Not a pretty sight. Part of the problem was caused by sagging,but part was shrinkage. I am currently propping the roof with a skilfully-placed [I hope] shelf,and will probably buy some more [but this time high temp] board and redo the shrunken bits. It won't give me a new kiln,but I still want to know if that system of building a roof can work.
This has been one of those classic studio pottery episodes where you try something new- it fails- you get disheartened- some time goes by- you realise that it's maybe not as dire as you first thought [ you also realise the dumb thing you did] - in fact,you now know what you have to do next- you feel a lot better. Happens all the time,and catches me out every time.