15 October 2008

Wood Chamber: Loaded

There were several comments about the bottom of this chamber being empty, and, of course, Michael Kline had it figured right. I've only fired this kiln 4 times and I have struggled to get heat to the bottom. It is a very tall chamber (6') and I worry that I'll never solve it. This is the first two chamber kiln I've built and I still have lots to learn.
I did open the bag wall and lower the packing place for firing #3 (the 'Kelvin' firing'*), but all it did was drop all the ash on the bottom shelf and it ended up even colder. I would be happy to hear suggestions if any of you have any ideas.
Today I'm getting out to the studio early and will begin to load the salt chamber.
(* During the night time shift, Paul and Bill managed to switch the pyro reading from Fahrenheit to Kelvin! It was more than a little confusing until we figured it out.)





6 comments:

Joe and Christy said...

Dan-
I apologize ahead of time if I insult your intelligence. Your a much more experienced potter than I am, but I can't help myself.
It seems like your problem should be able to be solved. Assuming that in the firings that you tried to heat the bottom, you opened the chimney up all the way, and still couldn't get the flame to pull across the floor. Then I guess a bagwall adjustment is your only option left. Just keep raising your bag wall up, and opening larger openings in the cold areas.
I hope you find the advice is mildly helpful and not just a waste of your comment section. Maybe Micheal Kline has more wisdom for you. I know that these problems can also be addressed through stoking patterns, but I don't have any experience with bourey box kilns so I can't comment on your situation.
Joe

brandon phillips said...

my kiln is a crossdraft and i initially had the opposite problem because i had such an open bagwall. the pull of my chimney is so strong that i could fire the bottom several cones hotter if i wanted. but i know nothing about bourry box kilns. i do however get a bunch of ash at the bagwall on the bottom, i just have to choose carefully which pots are going to get it. i hope you can fugure it out, thats some valuable real estate!

doug fitch said...

Mine's always cool at the bottom - I've messed about with the shelves, redirecting flues etc. which helped a bit. Also a soak around 800 seemed to help it catch up a bit, but I've pften thought of just firing it empty or with bisc pots - I only fire to about 1080.

I hope it's a good firing, I'm looking forward to it, good luck, don't burn your beard ;)

Dan Finnegan said...

Thanks for all your thoughts. I'm trying a few different 'tactics' this time to see what I can learn. I will side stoke directly into the chamber instead of only using the firebox. I believe that what is happening is that I don't have a hard enough draw as the chimney is pulling through the salt chamber first. And I know that the bagwall is a factor. I did raise it a bit for this firing. Next Tuesday will tell. I'm sure I'll have more questions then...and maybe a few answers. I love this!

John Tilton said...

Hi Dan,

Not that I know anything but what would happen if you had no bag wall at all.

Would all the heat just pass through the bottom of the kiln, and no where near enough go to the top?

Is there a way to find the balance point?

From a guy who mostly fires electrics. And if not electric, then gas.

John

Joe and Christy said...

Dan-
Are there any diagrams of your kiln? I've been thinking about it alot. Could be the reason none of the lids I made today fit that well. I remember your article in the 'Log Book', but I don't own a copy of that issue. Is the first chamber the only one that has the cold spot? I would imagine so, as there is no rise between chambers.
Good luck with the firing
Joe