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Firing Log

ancient kiln | 21st century logbook

April 2, 2006

Firing Update, #6

Filed under: anagama, 6th,Firing — odin @ 4:00 pm

The firing is over. I called it this morning (April 2, 2006) around 5:00 am mostly because there was a collapsed shelf. It wasn’t a failure though. I finally feel like I can fire the kiln. As I spent some time peeking in the kiln, I realized that it fired extremely hot and glassy. The walls have become glazed to an extent far in excess of the first five firings combined. I was amazed as I looked inside when I saw a blob of glass drip down from the ceiling like a big spider dropping from a thread. The bead dropped and the thread just hung there for ages.

I also understand the kiln monitor issue. The probes are encapsulated with glass. This either insulated the probes or affected they’re sensitivity in some other way. This is the last time I let a number on the monitor influence my thoughts. I still like to have the monitor, because I can correlate what I see from the chimney and hear from the kiln with whether the temperature is rising or falling, but achieving any particular number is completely irrelevant.

Talk about hot too — the shelves look like lasagna noodles, thin pieces unimaginably warped, as if they melted over their wadding. I suspect a 25% retrieval rate will be generous. Despite the obvious failures in these regards I am ecstatic. I wasn’t positive I could fire this kiln to a glassy result.

Last firing, I made the firebox area a little bigger and results improved from firings 2-4: the 5th firing had decent glaze and a lot less black crud than those intermediate firings. In this firing, I made the firebox bigger still (too big) and it got even better. Obviously, the sweet spot in this kiln is somewhere in the middle and I’ll be able to hit it next time. Now I can focus on other issues.

Stacking shelves is difficult beyond belief in this kiln. The obvious solution is to make stuff that fits the kiln better and doesn’t need shelves. I think in the next firing I’ll make only two rows of shelves — the rest will be pieces made to fit the size and shape of the kiln at the various levels. I already have some ideas for things to go there and I’m very excited. Can I wait till September?

As for a kiln monitor to use till I’ve trained my eyes and ears to be all I need, I think I’ve thought of the perfect solution. I’ll make a thick rectangular slab shaped piece with a built in prop so it can be stood on edge easily. At the top, I’ll put in some gravel size feldspar chunks. When those melt, I’ll have glaze. More pulls too. I suppose I’ll have to have a center shelf right behind the firebox to raise these test pieces above the coal bed — perhaps a pillar of bricks would work best. A 9″ square pillar 18″ high will not fall over.

Anyway, now for the really hard part. Cleaning up the kiln site, and even worse, waiting for the kiln to cool! Maybe I’ll go pitfire something in the hole I dug getting dirt for the ceiling.

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