Firing Log

I built a raku kiln 4 or 5 years ago. Alan (you’ll see him below) taught me how to weld and donated some expanded steel. I zipped it up with a MIG welder — the welds are certainly amateurish and a pro would laugh, but it’s held up. Welding is a heck of a lot of fun — I wish I could come up with a good excuse to weld often but alas, that raku kiln has been my one and only time. Here’s the basic setup:

Today, Rachel (green shirt), Tony (red shirt), Alan (picking piece), stopped by to fire off the raku kiln. Every since building the kiln, it has been living at Alan’s … but certain changes necessitated its move here to the anagama site. Today was its first firing here (discounting the one that didn’t work for lack of a wrench).

Alan’s new and unusual color:

I lost interest in raku quite some time ago — the results aren’t really what I’m after. I don’t mind white crackle so much but I became disenchanted with bright penny coppers and turquoise blues. Those results are pretty in their way — they merely aren’t what I want. However, I do like the actual orange and red colors in Alan’s new glaze.

Today I recovered some of the raku spark — could I “once fire” a piece? What the heck — no harm in trying. I went into my studio and grabbed something that hadn’t made it into the last anagama firing. It was an unbisqued (I don’t bisque) small slab bowl. I applied some white crackle glaze with a brush to the inside of the bone dry piece, and then set it on the kiln during the others’ firings in the hope it would dry sufficiently. It spent about two hours drying although I had to remove it between each kiln opening.

When Tony, Alan, and Rachel were done, I put mine in the kiln. I decided to raise the height of the shelf so the piece would be more in the middle of the kiln away from the burner. I hoped that would provide an environment a little gentler than it would receive on a low shelf. We set the kiln shell in place and I covered the outlet hole with piece of metal to keep rain off the piece. I decided I’d let the pottery preheat by sitting in the warm kiln with the burner off for 10 minutes. The firing would end the moment we heard the piece break.

The piece didn’t break sitting in the warm kiln, so I turned on the heat a tiny bit and waited for that dull pop of exploding pottery. It never came, so I bumped the heat a tiny bit again. And again. And again. When the paint on the piece of metal started to burn off, I cranked it to a low roar. Still no breaking noise, and the paint crackled into fascinating patterns:

I bumped it up to full throttle. I could see the glaze melting and the piece glowing. After about 70 or 80 minutes, I stopped the burner, Alan and Tony lifted the kiln, and just like any other piece of raku, my once fired bowl went straight into a post firing reduction chamber. I’m in the browncoat (same one I wore to the opening night of Serenity in true geek fashion — I much prefer Firefly though).

In my impatience, I pulled it out too soon to douse it in water — it was at that point the foot fell off. No matter — I’m confident I can do once-fire-raku again. I won’t ever buy a bisque kiln.

I managed to get through Monday without any peeking. Really, the kiln is much too hot but the temptation is strong. To take my mind off things, I decided to build a paper kiln. I’ve been reading about these since college (15 years now) and I’ve always wanted to try one. Sunday night when I got home, there was a Sunday paper on my doorstep. It was a sign. I don’t subscribe.

Now, I also had a hole from getting dirt for the top of the kiln. Given a hole, a free paper, and a spike-pod piece that had been sitting around for a couple years because the tip of the spike got broken somehow, I decided Monday was the perfect day and this was the perfect project. It would give me something to open today and thus help me get through two days of the cool down period (ideally, at least ten days).

Let’s start with the hole:

I threw in some damp wood. This turned out to be a mistake because I couldn’t get it to light. What I needed was some thin kindling underneath the bricks that make up the floor — there is an air inlet underneath the top layer. I should have filled that with easily burned wood. As it is, I had to resort to the raku burner to get the thing going.

Then I filled it in with some millends. The millends are fairly damp too — they aren’t kiln dried, but being cedar, once they get going they burn like the devil:

Then I piled up more wood over top. They say that early kilns were simple pits with shards placed over top to help hold in heat. I don’t have any appropriate shards (I have lots of shards, but when I smash up stuff, I smash it into little bits), but I hoped the paper/slip wrap would function similarly. As it turns out, one Sunday paper isn’t quite enough to make a nice thick shell — it was only a double layer at the bottom and when things got going, it ripped:

Mixed up some slip (twice, needed 3x this amount):

Grabbed the paper:

And pasted it up, threw dirt on for good measure. Dirt is the cheapest most abundant refractory around. Great stuff:

I threw some hot coals down there and started waiting. Although it looks like they caught, when I’d pull them out the smoke would go away, so the smoke was from the wood I threw into the air inlet, not from the kiln wood:

To make a long and rain soaked story short, I eventually got it lit. But then it smoked like crazy — thick green smoke — the kind that looks like a liquid. The smoke was was bothering me a lot and although I knew speeding things along would damage the unbisqed pot, I was mostly interested in seeing some fire so I forged ahead anyway. I fanned the flames and indeed, heard some ominous pops from the kiln. At last it really took off and boy, what a sight:

Notice the cat in the middle to lower left. The kiln’s cats LOVE fire! Click the pic for large version:

Today, I retreived the pot. When I got to the pit kiln, I saw shimmering heat from the sides of the dirt walls. That surprised me … till I realized it was a shimmer shadow from the anagama chimney. I’ve never been much for pit fire and this piece hasn’t convinced me there’s anything there for me to do. Here’s the rather bland piece:

But then I turned it over. There’s glaze on the foot! Honest to goodness glass! I cursed a bit in a surprised and happy fashion. As arrogant as it sounds, I thought to myself, “if I can fire a hole in the ground to a glass finish, I can fire anything.”

Clicking on the following pictures opens a large view:

You can see the damage from pushing the fire, but so what? Glaze!

Here’s the worst hole:

The best was yet to come — something even more interesting than the pottery itself. When I dove into the pit to retreive my bricks before filling in the hole, I discovered the dirt had melted — really melted! I was simply amazed — it’s very brittle, but very cool. I’m thinking about incorporating dirt with firebox pieces in the anagama itself:

So there it is. I can melt dirt. What a great day and better yet, one more down in which I did nothing with the anagama. I have to work the next three days so that will help too.