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Firing Log

ancient kiln | 21st century logbook

January 25, 2009

Premature Thoughts on the 11th Firing

Filed under: anagama, 11th,Firing — odin @ 5:19 am

Gray junk. Now I don’t mind koge and it looks great on certain pieces. I’m not talking about that. I hate how some firings tend to leave a layer of embedded soot on the front of my pieces. The results are decidedly not pleasant and should not be confused with koge. Over time, I have been letting more and more air into the kiln and I’ve had a reduction in the amount of ugly soot-glaze — but it hasn’t gone away completely.

This firing, I decided I would do no heavy stokes of the type that result in pillars of yellow flame emanating from the chimney. That yellow flame is merely an indication that large amounts of carbon failed to combust inside the kiln, and are instead, flaring off in the atmosphere. At least that is my thinking. The flaring is accompanied by temperature drops, and followed by temperature rise when it ends. Obviously, the kiln is in insane reduction at that point.

I am wondering if that level of reduction is necessary and so I decided that on this firing, I would avoid the massive yellow flames. I had plenty of red witch’s hat style flames, but that is more a glow of hot gasses than fingers of fire. It was very easy to raise the kiln temperature to very high levels by stoking small amounts (single stick) as soon as the witch’s hat faded away. It would return for a short time, fade, stoke, return, fade, stoke … etc. till exhaustion.

Cone 10 dropped after an hour around 34 mV, and cone 11 dropped at around 35 mV. I hit close to 37 in the front of the kiln and 38.2 in the back. So way overfired no doubt. Even with the avoidance of yellow chimney flames, I saw plenty of black smoke seeping out of the cracks in the kiln — I doubt this is a complete solution to my grey-gunk-but-not-koge issue.

Right now, the kiln is cooling and I won’t be able to open it for many days. As a result, I’m now second guessing my experiment and worrying that I made a terrible error. Sigh. I really dislike the space between closing the kiln and opening it.  Instead, I’ll think back to the start — to the time period when I’m full of hope and anticipation. Preheating. This is how I do it:

3 Comments »

  1. Great to see you back!

    Comment by Stu Buss — February 1, 2009 @ 5:55 am

  2. Okay,I had a good hour and half checking things out- thankyouvery much!
    Somehow I had not looked here before,thanks Odin…really nice…my scene seems quite chaotic and less precise by a long shot…
    daniel

    Comment by daniel stark — February 11, 2009 @ 10:35 pm

  3. I am so delighted to find someone else on the trail of “get koge instead of gray gunk”. I fire with some else in their ana/noborigama, and I miss getting the koge I got in Japan with John Dix, a god of koge, in my book. I’m building a modified anagama this summer, and want to ensure I can get some of those koge-goodies. I like yakishime, shiga-style, with koge accents…. Your site is great, thanks. Sue

    Comment by Susan Kotulak — April 30, 2009 @ 9:52 am

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