We just wrapped firing number six of the #BelugaGama.
There were a few new things going on with this firing that I feel are worth sharing.
We mudded the chimney base up to a newly installed active damper which is just above the corbleled section of the chimney....for down-firing. Huge increase in draft control. The active damper slot was left open throughout the firing and closed upon starting the redux cool sequence.
For the first couple days of the firing, we kept the in-chamber active damper closed about 75%...that is once we started ramping up from around 300 degrees (we did a two and a half day pre-heat with active dampers open and passives closed). Full draw was used in the pre-heat...active damper open and passives closed.
Once we hit the "wall" at 2150ish...pulled the in-chamber actives and opened the passives on the back side of the chimney. Backpressure was maintained until then using the in-chamber active damper and was nearly replicated, with a slight loss of backpressure, when the passives were pulled. The kiln stopped consuming wood like a hungry teenager at that point...we burned through 2 cords of hardwood up until that point. One more cord brought us to top temps a day and a half later. It was a breakthrough to figure this method/draft-change out for sure. Finally, backpressure and temp maintenance/gain happened w/o a struggle ;)
We used a blend of Rock Maple, Ash and Fir this time around. The Fir, along with pretty dry wood, created a scenario where clinkers were no issue in the below grate section of the firebox.
All in all, a smooth firing.
Down-Firing: Steve Johnson ran the down-firing sequence...Kiichi Takeuchi and I helped. 5 minute redux burn followed by 3 minute clean out periods down to 1600....12 hours total. We're hoping for awesome results but have already taken steps forward in understanding and controlling the kiln atmosphere and temperature rise.
I'll post pics of the results in a couple days. I'm hoping some of this info is interesting to some of you out there. All my Best, Trev