Oxidation

[offcntr]

Club Mud's big kiln is both wonderfully predictable and horribly random. I know that if I follow the usual steps, I can make cone 10 in the usual amount of time using the usual amount of natural gas (66 units, more or less), with roughly equal temperature top and bottom.

I also know that there'll be oxidation somewhere in the load. It's an old kiln, leaky in spots, and the door, at least, is ready for another rebuild. No matter how carefully I watch the damper and burners, a certain amount of oxidation is a given.

I don't like oxidation. The pots come out too white, the rutile and orange stain bleach out. There's no warm tones, no iron spots, no depth.

In a good fire, I can count on the lower left front of the kiln showing some oxidation; in an okay fire, there'll be patches higher up, or a corresponding spot diagonally opposite in the right rear quadrant.

This last firing was just nuts.

I loaded a bunch of animal banks down in front, Empty Bowls further back. The bank glazes are more or less immune to kiln atmosphere, and the Empty Bowls will be donated to a charity sale, so I tolerate a lot more variation in color there. But both the banks and the bowls were perfectly reduced.

This time, the oxidized patch was higher up, two complete shelves, front to back. It was like there were two bubbles of flame in the kiln, with some sort of thermocline separating them, and these two shelves were right at the divide. I lost all of my small serving bowls, batter bowls, a bunch of baking dishes and pastas. I didn't lose any special orders, thank goodness, but I'll have a lot of work for the seconds sale in Albany next month.

And a big head-start on the throwing list for my next firing.