Monday, November 3, 2008

First firing summary

We finished up our first firing last night about 10:30 pm. I'll come right out and say it, I think our kiln is going to be great. The kiln seemed pretty responsive, in our 48 hour firing we never opened our damper past half open, we left it a majority of the time at a third open. So I'm sure in the future if we want to fire a load of glazed pots we could do so in 20 hours. Of course the fact that I think the kiln is going to be great doesn't necessarily mean that the first firing was great.
I'll give a short overview, then maybe mention the good points and bad points. I hope I don't bore anybody, and I apologize our digital camera broke last night. So this will be a text only post, which is unfortunate as I don't consider myself much of a wordsmith.
We started a small fire Friday night, I stayed up till 2am then headed on in. Christy started it back up the next morning around 5am, held 200 degrees for a couple of hours then started slowly pushing the temperature up. We kept the flames underneath the grates slowly raising the temperature. This is where we ran into our first problem. The way the grate supports are stacked up they create a 18" wide trough the length of the firebox. This ended up being too small a space for all the embers while we were stoking underneath the grates. We ended up having to move to stoking above the grate around 1000 degrees. I would have liked to not stoke on top of the grates until 1300-1400 degrees, but this should be fixable for the next firing, as the grate supports are not mortared in place. I think I can stack them in a checkered pattern to allow the ember to spill out to the sides. We reached 1800 degrees Sunday morning and started reducing. We kept it in what seemed to be a fairly heavy reduction (first firings always seems like a guess as to what reduction you are achieving) all the way up until cone ten started to move at the front of the chamber early afternoon. We then switched to holding the temperature letting cone ten in the front of the chamber slowly fall. This period seemed to be almost oxidizing. We held that temperature and worked on evening out the temperature in the middle of the chamber: top to bottom, left to right (the middle cones were 7-8). We held that temperature for maybe five hours, then pushed cone ten down in the middle (also pushing back into reduction). We had one cold spot in the first chamber which we could not figure out, cone 9 was as good as we could get. We closed down the stoking in the first chamber, and started on the second chamber. The second chamber seemed to move very well. We had cone 10 moving on the floor and cone 9 getting soft on top. Then our bagwall fell over. Bummer. Luckily it's fall was stopped by the arch so nothing got broken. We built our bag wall very quickly out of broken half bricks and arch bricks mortared together figuring it only had to last one firing. Unfortunately it only last 80% of one firing. We got cone ten down on the floor, and cone 9 at a half on top, but with the bag wall resting against the arch we decided to call it a night.
Wow, anybody still reading this? I'll end it quickly, the firing was very good for a first firing. The pace was relaxed, the kiln was responsive, and I'm excited to unload. Excited for the next firing as well, maybe March. We'll see if we can sell enough pots to be able to afford to keep making them full time. Christy's starting a temp job till Christmas, and I'm going to try and figure out how to sell some pots.
Joe

4 comments:

Michael Kline said...

Congrats to you you guys. I was sorry to hear about the bagwall, but it doesn't sound like it affected the firing. I look forward to you describing the pots that come out. Or are you going to get another camera? Ha.
Best of luck, thanks for the summary.

Tim said...

Sounds great... can't wait until you get the camera fixed so we can have a look. I'm about to go help David load his kiln up, right after we win this election.

ang said...

excellent commentary, hope eveything works out job wise & selling pot wise, congrats on 1st fire.

Brad Lail said...

I cant wait to see what comes out of that baby! Nice firing detail. I enjoyed reading it and am excited to see what changes are made for the one in March.