It was a very hot firing — cone 11 laid flat front to back (I don’t have any higher cones). However, I think getting it so hot is detrimental in that the glaze tends to run completely off vertical pieces. There are two problems with this — first, the glaze is gone, and second, foot grinding is a huge chore. Perhaps in future firings I will work on controlling the maximum temperature to no more than cone 11.
What was most excellent however, is that I avoided the gray-gunk I mentioned previously by not overstoking. I figure that when overstoking, I probably have a lot of gritty unburned wood particles flying through the kiln. With optimal stoking, I still got blackening on the front sides, but the carbon creates an inky black glaze rather than 30 grit sandpaper. I’m completely OK with inky black glaze — it looks neat.
I also finally managed to mimic the surface of the floor bricks on a piece, specifically, the blue marbled glaze that forms where the floor sand melts onto the bricks. The sand itself is inexpensive white sand that I buy at Home Depot — last time it was around $5 for 100 pounds. The result is beautiful and the piece below is one piece I feel completely happy about. It makes me want to get a bright light and a magnifying glass and mentally tramp through the mountainous landscape.
First, inspirational bricks:
A snow capped mountain range:
I also experimented with some local clay I was given a while back by a friend doing some construction work around his house. The clay he gave me is everywhere around here, except it’s usually 4-6 feet down so getting it is difficult. It is a blue-gray color in its natural state. When I made some test pieces with it (full report here), the 100% “dug-up” clay melted into a beautiful glaze. For this firing, I decided to try lining some of my pots with this clay. The results were interesting.
First, the failed cup:
Same clay used as a liner glaze:
Finally, I’m also very happy with my new kiln monitor setup. I had been using the software that came with my Radio Shack Digital Mulitmeters. It was lousy software. Recently, QtDMM has been released for Linux and OS X. I put together a system with an old Mini-ITX board powered by an aging VIA Nehemia 1ghz processor (think 5-6 years old). I used Ubuntu 8.0.4 for the OS.
The added processing power over my old system (it died between the this firing and last year’s) allowed me to set up a chimney cam — basically just an old DV camcorder connected to a firewire port. I used Kino to display the feed. This helped save my knees. What I used to do is go up the steps to the mid-level, and peek at the chimney tip through a gap in the roofs covering the kiln — when I saw the flames die out, I’d run down and stoke. Well, my knees are getting beat up by running up and down the stairs during these firings. Now I can just stand by the kiln and watch the chimney cam.
This is what I used to see:
This is what I see now:
When all is said and done, I’m totally satisfied with this firing.
PS: if you’ve made it all the way down to the end, enjoy a sunrise: