24 October 2012

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.

17 October 2012

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.

3 October 2012

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