After taking things slow for about 12 hours, we took the kiln up to cone 11 over the next 24. Finished up at about 4am Saturday morning, quite a bit earlier than I had planned. Earlier in the firing, I had thought it would take longer, because the kiln was not really responding to the stoking and seemed to be reducing strongly, making me think that I’d perhaps closed the flue channels a bit too much prior to firing. However, after cone 9 started to finally go down, we started to get that great growling roar following every stoke, and pretty soon cone 11 was bending. Here are some sequential pictures from the firing.
Nakayama kun stoking under the grates during the preheat, we kept it at around 250C or under for about 12 hours.
After we got to about 1000C, we started getting smoke.
The castable on the second chamber splitting along the line I was hoping for….
Cone 11 is half over and Nakayama kun is starting a stoke.
It almost feels as if the flames will push the stoke cover away from the kiln wall. Without the rod propped against the cover, the flames come out in all directions.
The chimney after the stoke, it is about 3 am.
After I clammed up the kiln for good, there was still enough fuel in the form of embers to keep burning pretty strongly. I was a little worried about inadvertently over reducing when I saw this. Not sure if this was good or not, I decided to open up the rear damper again and let some of those excess calories exit the kiln, however the extra oxygen just cause the temp to start rising again and after about 10 minutes I shut the damper again. By then the flames subsided quite a bit.
Here is the door all mudded up, because there was a good 5mm space all around the door where the kiln had expanded.
Notes from this firing:
-I may need to open up the flues a bit to get some more air flow.
-The insulating castable on the front wall and rear chamber is AWESOME! Even at cone 11, I could keep my hand on the castable surfaces.
-Pyrometers are not to be trusted. The highest reading I got the entire firing was 1056C, and this was when cone 6 was about half over. Moreover, as the kiln got hotter the range of the pyrometer readings actually became lower and lower. Not sure what this means yet. I’m thinking right now that the pyrometer is not extending into the kiln far enough, and pretty much is just responding when directly exposed to flame.
We will be unloading on Wed. I will post pictures shortly after… I can’t wait…