Higham Hall anagama, October 2012, firing continued

Shozo Michikawa pot, made and fired at Higham

.....a bit more detail about this firing now that I’ve been home 10 days already (I haven’t caught up with everything just accepted that some of it’s late and some forgotten and some just won’t get done)

Frustrating firing given that it failed to reach a good temperature. All those pots, all those miles, all that time. On the other hand lots of good company, lots of superb weather and lots learned.

We had a nice easy climb for 10 hours up to 900ºc using lots of the small wood (I mean very small wisps of wood bundled together, 1 - 3 ft long, 1/2 - 2 inches thick).
Then 4 hours of reduction keeping the temperature around 900º, building up ash in the chamber, using the damp wood.
The next 6 hours saw a slow rise of 100º up to 1100º. This would have been fine if the stokers didn’t have to endlessly rearrange the wood piles in an attempt to dry the wood around the kiln. It was tiring.
From hour 18 (4am) until hour 26 it hung around 1120º finally getting to 1150º at which point we started to feed in the soda through the fire box. We use Carol Nicols recipe of bicarb, soda ash and whiting.
Hour 32 and we’re at 1196º, the maximum achieved on the pyrometer.
Then 6 hours of consistent heavy reduction, continual feeding of wood which ignited before you could get it into the fire mouth. The fire had nothing substantial in the grate to maintain, let alone increase, the temperature. The ash pit was closed up as there was little ash to pre heat the incoming air. And the continual pyro watching, trying to get just a few more degrees.
By hour 39 at 1 am with the wind picking up and blowing onto the long side of the kiln we were actually losing heat so we started on the ton of big dry logs saved for the last stage of firing. Turned off the pyro, turned off the stress.
Now here’s the part which I don’t understand. Using the big logs gave a fire of white heat, minimal reduction, over a period of 4 hours, yet the pyro reading on the hour every hour, showed a decline in heat. And when we unpacked cone 10 was down in various parts of the kiln but most of the glazes were not matured - the exception being a pot of Shozo’s from the ash pit which somehow managed to be fabulous.

Higham Hall College, October 2012

Despite perfect weather for firing this was not our finest hour, or rather 44 hours. I am inclined to put its failings down to wet wood. We had a ton or so of 60cm long split logs nice and dry in the garage and 4 bundles of offcuts ordered of which only 2 had been delivered. Despite being under tarpaulins the seemingly continuous rain of the summer had left the wood at 30% moisture content (according to Rob's moisture meter gizmo) and the final 2 bundles delivered the day before firing were wetter than the driftwood I pick up on the beech at home.
The lovely Will arrived on Sunday to chainsaw up the bundles and agreed to return on Monday to deal with the second lot. Size matters when it comes to chainsaws, I only wish we'd found Will for the last two marathons of sawing - we were knackered then before lighting the first match. This time we were knackered from the continual rearrangement of wood on and around the kiln as we tried to dry it out. These bundles were of very small bits, far too small for the later stages of firing, and no time to sort it either. Not a perfect arrangement but better than no kiln at all!
Sunday we chopped and stacked wood, straightened the chimney with longer angle iron and brackets and threaded bar top and bottom, and set up tables and the wee pop up marquee which extends the shelter in front of the kiln. Monday was loading day although some precious time was spent on wood. It's a long slow process and so important. I'm not sure we'll ever make the best of it. We each have our own preferences for wadding, dry/sticky, white/flashing, course/fine, and many of the wads fall off by the time the piece reaches the person doing the packing crouched in the bowels of the kiln. More research needed on this. I like a fireclay/course sawdust mixture which flashes nicely and sticks well  to the pots, but it also sticks to hands which is not appreciated by porcelain.
   By the time the light was fading it had already been a long day and there was still dinner to make and the door to brick up and some clamming of holes to do. It was a tighter pack this time. More shelves, lots more pots, one more firer (5 of us). We had put the gas burner on  through the damper at the base of the chimney for a few hours earlier, which was a good move as it dried and warmed up the chimney to improve the draft. It gets very wet sitting through 6 months of Cumbrian weather between firings.
Overnight on gas into the firebox took the temperature to 100? Then we lit a small fire in the grate at 10am and so began the rota of 4 hour shifts, 6 hours off for the next 45 hours.

Glazing for anagama

Two days to go before setting off for the next anagama at Higham Hall College.
Glazing nearly finished, the concentration needed is tiring but I've finally learned to give myself enough time. And I made notes, so there's a chance I'll know which glazes are on which pots when they come out of the kiln - must record where they are in the kiln.

I love the chemistry of ceramics (not very good at it mind you) but the glazing I used to find painful, physically, like those awful cross country runs at school, close your eyes, scream and launch yourself through  the cold, muddy puddles - that's how I've always felt when glazing, it only gets better once it's all over.  When I was making slip cast earthenware, one glaze, resist decoration and cobalt wash, it was simple but tedious; raku glazes seem to smother my textures so I don't use much in that medium; I never knew enough to be in control and I think I just didn't like the glazes I was using or the results.

But now,  I think I'm almost enjoying the process. The simplicity of wood fire glazes is beautiful. The basic ingredients are identifiable as rocks, clay and ash. The process of their melting is imaginable and there's the possibility that the combination of ingredients and fire will produce a moment of pure magic way beyond the sum of its parts.

No photo, you have to imagine your own perfection

The firing, continued...

 Lovely new cladding on the kiln.  Fire clay, vermiculite and a bit of sawdust. It was like plastering with porridge only less salty. And had the added bonus of making the arch look a little more professional. The green posts are ex-tennis court posts rammed into the ground, wedged with bricks and wired together over the top in an attempt to counterbalance the desire of the arch to become a pile of bricks.

And lo and behold the whole construction held together, rather well actually, and looks a whole ot better than the ware chamber.
The new arch is a proper roman arch and considerably higher than the old one. Had we thought about it we should have lowered the supporting walls by a course or two. We weren't sure how this extra volume of the fire chamber would affect our ability to reach temperature. The results, after 40 hours of stoking dry pine slab wood was cone 10 melted almost throughout the chamber (middle back cone 10 was just down). To my eye, the best firing yet, some lovely natural ash glaze, good crusty effects in the firebox, not too many collapses, not too much reduction. We could spend more time building up ash deposits in the next firing being fairly confident of achieving a good temperature if we have good wood.
More detail of the firing log soon. photos next

Back to Anagama in Cumbria

  Back to Cumbria before I forget too many details.

After 60 hours I had the feeling to stop. Already 20 hours more than the previous firing with cone 10 down at the front after 30 Hours. So we are certain we have achieved much higher and more consistent heat  than before. I would have liked to have seen the results from this point of the firing but we are on a roll. There's still half a ton of wood left (good and dry to start the next firing I argued) but pyromania takes hold and we keep going.

 The wind picks up. Not so good for pizza on the flue, the top won't cook despite the covering kiln shelf.  Two seconds at the open fire mouth sorts that, five seconds and it's carbonised. The wind is in the trees blowing crazily. Little oblongs of light between the bricks at the top of the chimney become bigger, squarer, lower down too. The chimney is listing away from the kiln. Loud harsh cracks from a tree as it starts, in slow motion to snap. It's not offering itself to the firing but seems to want to get away from it. It's the only thing to pull our attention away from the kiln.

The wood is running low, the rain sets in, the chimney looks dangerous. The kiln is as happy as Larry, I have the impression it would continue for another 6 tons and reach higher temperature.   We call time, I'm really a bit scared that the chimney might go, like a giant red hot Jenga.  As we load up the fire box to finish off, the tree finally snaps and twists as it falls across the drive.
72 hours.

Anagama in Cumbria

November in Cumbria is not the best time for a firing but it's still better than Skye has been this year.
Ten of us arrived at Higham Hall yesterday, 6 tons of wood waiting for us under tarpaulins and a sad looking kiln. Last years winter frost has caused a bit of heave and the arch is looking distinctly flat. Should hold up and Gavins big pots are strong enough to withstand a collapse so they're at the front!  
This is a much tighter pack than last year. Lots more pots, new shelves and props. About 4 hours to pack (photos later) and brick up the door. Gas on low overnight to dry it out after 14 months of Cumbrian weather. 120 C at 6am this morning. Small wood fire in the ash pit and up to 240 C by 10 am. That's me off shift until 22.00 but we're aing for 800C by 18.00.

Firing 14 - refiring most of firing 13

Another 5am start, pitch dark but starry. Gas burner on.
7am   100oC   gas up, weather is still, overcast and damp
9am   310oC   gas still on, damp wood, damp kiln, did not do a warm through yesterday, kiln steaming - low fat pots?
10am  480oC  gas off, hard work to keep this fire going. Am I tired? not really enjoying this
11am  616oC  south west breeze. Now the fire is more beguiling, it becomes a reason in itself to continue. The kiln has ceased steaming
noon   730oC
1pm    878oC   using large slab wood, strong s.w. breeze
1.30   1004oC  reducing for a good half hour
2pm   1024oC 
3pm   1088oC   first soda in. Cold s.w. wind blowing into fire mouth,
3.30pm              closed the big doors for shelter
4pm   1088oC    then at 4.05 up to 1126oC
5pm    1145oC
5.30    1165oC   Andrew stopped by, just to check that the flames were intentional
6pm    1166oC  
6.30    1200oC   cone 7 bending
7pm    1203oC   cone 8 bending, 7 down
7.30    1211oC
7.45    1187oC   cone 9 beginning, cone 8 down
8pm    1215oC
8.15    1220oC   cone 9 down, last big stoke, start clamming up the kiln, a few slivers of wood added during this.
9.15    1078oC

I didn't make a note of when I put the fire mouth door on, probably around 1000oC to assist the reduction. It made a big difference to the comfort of my knees which would be scalded without the door. It was along hard firing this one, the longest so far at 15 hours, damp wood, cold south westerly wind all having an effect. The rain held off. I thought that the wind in this direction would speed it up as it blows directly at the fire mouth, my perception is the opposite. Will have to try it again with drier wood.

happy kiln = happy potter,

  This was a much better firing, even though I could hardly walk the next day - 15 hours on concrete in the wrong shoes.
will post some results next.
I think this blog is getting repetitive, not enough crises with this kiln. By the look of the interior it will need a rebuild before the chimney wall slumps.
Meanwhile I have been planning an anagama firing at Higham Hall in Cumbria for November.