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Firing Log

ancient kiln | 21st century logbook

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April 2, 2006

Firing Update, #5

Filed under: anagama, 6th,Firing — odin @ 1:45 am

11:06 pm, April 1.

I’m hoping if I write a bit, I’ll be able to stay awake till dawn. At this point, it isn’t clear to me that I’ll make it. Exhaustion is catching up with me. OK, take a deep breath. This is fun, an adventure. The sort of thing that makes good stories later. I enjoy this. The longer I stay up, the better bed will feel.

So I need some topic — how about “worrying”. I’m a worry wart (wort?). There isn’t anything I can’t worry about. A glass half empty guy and I’m noticing that the glass is cracked and leaking.

So today I gathered up all the bricks I could find. I don’t have a ton of leftovers. I came up with 24 bricks though, enough for four courses at the top of the chimney. So I raised the chimney 10 inches this afternoon. Here’s what I was thinking — the wind that I’m missing helps increase the draft. If there is no wind, increase the chimney.

So I do that (as if 10″ on 96″ chimney will have a significant impact) and immediately start worrying about black crud on the pottery. Here’s the worry:

I’ve been thinking about building a wood fired bathtub out here. FYI, my last shower was Tuesday, so — yeah, it would be nice to be able to take a bath. I won’t go into the plans but it involves a natural siphon, metal cow trough, old stove, and some piping. Anyway, in my research I ran across some wood stove discussion on the net in which it was mentioned that controling the burn rate of a stove by the air vents instead of a damper causes a sooty chimney. Well — this kiln has no damper, the air vents control the burn. So I was thinking that may be the cause of my black crud. Seems the same principles would apply.

So, to come back from that tangent, I no sooner had 10″ more chimney when it hit me — that effectively makes my air inlet smaller and there might be soot buildup. I’ve been concerned about that for the last few hours. I took off one course a little while ago — I’ll probably take more off later.

All this because the kiln monitor doesn’t want to break 44 mV reliably, and instead hangs out at 42-43 mV and I want to go to 50. Drat! But make that a real swear word.

On the other hand, there are two loose bricks on the bottom side of the upper fire mouth — the stoke hole. They’re constantly being knocked in a little and then I pull them back with the hook on the pole if I remember. The tips of these bricks have become glazed. If I can glaze bricks that have air coming in over them from the edges around the door to the firemouth — things should be OK inside the kiln. Really. I tell myself this but I still worry.

Well, I haven’t checked my email in two days and I’m worried about what disaster will have happened at work, so I better do that now. Besides, I need to go fill the wheelbarrow again. At least I feel “awaker”.

April 1, 2006

Firing Update, #4

Filed under: anagama, 6th,Firing — odin @ 8:51 am

It’s 8:00 am. I’ve been up since 2:00 pm yesterday. I guess that isn’t so long but the sleep issue is catching up with me. Tony (a regular) is coming this morning — I can hardly wait. If one can see a mirage of sleep, I’m about to.

I’m trying to think of ways to stay awake, except I keep daydreaming about sleeping. One way is to get one armload of wood at a time from the shed instead of a wheelbarrow load. It’s much easier to stay awake when standing. I made some tea earlier because I knew the whistle would wake me if I dozed. I didn’t really want the tea.

I’ve been listening to This American Life, the Habeas Schmabeas episode is quite the listen. But now the stories aren’t keeping me awake — they are weaving themselves into dreams I have. So I decided to try to write an entry. It’s working and I feel much more alert.

I pulled the third pull (FN 1) from the kiln last night. Actually, I tried to pull the third but it got stuck and the loop for the pole broke. So I pulled out #4 — the last one I have. The glaze is very good (YEAH — relief arrived, I’ll just write this and go to bed — SO HAPPY). Even on the stoneware the glaze is thick and glassy. Porcelain never has issues w/ glassy glaze but my stonewares haven’t been doing so well.

It’s confusing though because the kiln monitor is showing a lower temperature than in other firings. Raising the temperature has been hard this time. First, there is no wind. I mean none. Fire shoots straight up from the chimney. I noticed the few times a breeze blew through that the temperature rose (gosh — feels like I already wrote about this). It’s usually blowing like the devil whenever I fire.

Secondly, I may have made a stacking error. Thinking back to the first firing, there was a lot of stuff tumble stacked in the kiln (FN 2). All us stokers being inexperienced, we smashed that stuff up pretty quickly. However, for the stuff that survived, the glaze was simply gorgeous. In subsequent firings I stacked closer and closer to the firebox and things got progressively worse and worse. Last firing, I backed off a bit and things got better. This firing I backed off more but maybe too much. Perhaps there isn’t enough mass in the kiln.

And right now, it’s pouring rain. Steam is rising again meaning water is cooling off all that soil I warmed. Did I already mention the curiosity with pyrometer? It 41 mV after about a day, day and half of wood — I can’t recall exactly. Then stuck at about 40. Early on, the fire was easy to look at: orange. After a day, the fire was painfully bright to look at without welding goggles.

A word to the wise — sleepy stokers suck. Tony’s getting the temperature back up, which is quite the relief. Another word, writing is quite a good way to wake up. I finally feel alert and awake — just in time for bed.

Anyway, last comment — the pulls make all the difference. Cones don’t work in this kiln (they melt early on), and type K thermocouples are notoriously inaccurate. But a pull doesn’t lie to you. If it’s glossy and coated with glaze, that’s what is going on. If it is rough and dry, that’s what is going on.

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1. A pull is just a piece pulled from the hot kiln. My pulls for this firing are like small baskets about 1×3 inches with a tall loop in the center. They’re made of the three clays I used most — sort of neopolitan.

2. Tumble stacking is a suggestion people often make to me. But it just doesn’t work in this kiln because the pieces get so heavily coated with glaze — it just results in glued together gobs of pots.

Pages: Prev 1 2 3 4 5
Pages: Prev 1 2 3 4 5

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