So today is the start of the firing. The last few weeks have been busy with last minute series of pots, splitting, glazing and loading.
The kiln is packed relatively tight...we found that a tight stack and a 12 hour hold around 600F dispersed ash evenly throughout the kiln the last firing especially. Thinking the tighter front stack especially acts like a screen the draws and disperses ash throughout the chamber...a discovery based on previous firings in which we stacked looser in the front.
There are five rows deep of shelves in the kiln and the first two counting from the firebox are exclsively stoneware...have found the porcelain likes the center section best...flashing and fine ash build up.
Our plan is to fire the kiln at 180F for 12 hours then move to a 30F/hour rise to 600F...so around midnight we'll start the 30F/hour heat rise again. Our goal is to be at around 1500 by the 48th hour. At this point we will pay extra careful attention to the atmosphere so as to allow for full oxidation before re-stoking.
By hour 72, we hope to be around 2300F and work the kiln to peak temp. and hold till hour 84.
During the initial phase..up to 1500ish...the passive dampers will be pulled to the point the we get the minimum draft necessary to maintain heat climb. After this, we will increase draft only as required.
Adjustments in the firebox occur mainly when we achieve orange-heat...at this point we close off the lower/primary air arch...this serves to increase draft a bit, keeps embers from accumulating and shields the stokers from excessive heat radiation.
Once we have held at temperature for several hours...we will introduce a half chord of Black Locust to provide the heat and ash that should get us to a soft ^12.
Shut down will be as usual...a couple wheel barrows of wood in the firebox followed soon after by a complete shut down of all air ports, peep holes and active damper...this technique has proven inself to be good way to achieve reduction cooling and flashing at high heat.
Each firing is so fun and exciting...the information gathered each time never fails to inspire the next firing. By far, the most satisfying aspect of the firing is the shared experiences with the firing crew. Mostly former students comprise the crew...a good friend Jim is a major contributor to the process....making pots, loading firing and unloading/clean-up. Without these guys there's no way this event could take place...so thankful that we've all taken ownership in the process of firing the Pyranhagama...without this process...may not see these guys regularly...good in all ways!