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.

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

Firing 23

No wonder I was twitchy, it’s 5 months since the last firing. According to the weather forecasts I shouldn’t have been able to do this one either. However a kick into action from the angels earlier in the week in and I managed to coordinate being ready for the only decent day we have had in weeks (months to be honest, though it feels like years, but this is NOT a ‘moan-about-the-weather’ post)

I’ve been putting myself under pressure to make pots ready for a firing here and for the Higham Anagama in April. The calendar is filling up with Potfests and galleries wanting work. I knew I would have to be ready to fire at short notice if the weather looked promising. It takes a day to pack the kiln, carrying glazed pots from the studio, wadding them, placing them, taking them out again, rearranging them to squeeze another one in or to get a better flow of flame around them. Too much wind and rain on this day makes it very unpleasant to pack. So really I like two good days in a row.

This time I had a potter friend from Aberdeen (Sjarifah Roberts) to help carry and pass stuff which was a great help although she couldn’t stay for the firing. She’s wanting to build a kiln herself and it’s SO much easier to understand all the variables of kiln design when you are actually standing in front of one. The books are great but nothing beats getting involved with someone else's build or firing.

The usual start at 5am to put the gas on low. I had given the kiln 4 hours of drying the evening before, even so it continued to steam like a sauna for the entire firing. I was concerned that the wood might be damp too from months of high humidity.
The morning was dry but overcast with a breeze from the west which continued for most of the day with a few showers and quite a bit of sunshine.
Firing followed it’s usual pattern at first although I kept the gas going for an extra 2 hours after introducing the first wood at 8am.
Normally I get reduction happening at 900ºc after 8 hours. This time it was at 1000ºC, perhaps the wind in the west was increasing the draft, it certainly takes the smoke away from the shed  very effectively. Generally it was a more oxidising firing with a low bed of embers which I only had to scrape out once.

Another potter friend (Robyn McGraw) arrived at 1pm and helped with the stoking for a few hours while I drove around the village looking for the dog who isn’t impressed with the kiln and prefers to hunt for bird food scraps that the neighbours leave out (and he steals my wood). The first soda went in after 10 hours at about 1150ºC. then two more lots during the next hour. About ? g in total.
Robin had to leave at 4pm so missed 1200ºC at which point there was an almighty downpour and i lost temperature which stalled the kiln at about 1160º. It was a long slow climb back to 1220, achieved by closing the shed doors and feeding one small piece of wood at a time for for the next 3 hours. Because the kiln is built mostly of HTI bricks it has a low mass and doesn’t hold its temperature for long. It was raining more by now and blowing from the south west into the fire box. Exhausting but satisfying finally to achieve 1220º for a while and see cone 9 going down.

Philadelphia Museum of Art craft show.
Where to begin? and how long have we got?
Not a kiln blog this one but the culmination of 6 months of making and firing. I found out in March that I had been selected as one of 25 makers to represent Scotland as the guest country at PMA Craft show in November. Serious stuff when put like that but no matter how insignificant I feel at times this was an opportunity I wasn't going to turn down.
So I worked my socks off in a very unsystematic, head in the sand kind of way. Trying new things with new clay and new techniques, 'throwing' old stuff into the mix and hoping to goodness  that there would be something decent at the end of it. I fired the wood kiln 6 or 7 times in 6 months (too much for one middle aged woman)  in all weathers (mostly wet this year), rakuing whenever panic loomed. With only half my mind focused on it, the raku work grew, thrived and blossomed. The hands know what they are doing. 

The wood firing was a struggle. I loved doing it but wasn't yet loving the results. One or two pieces from each firing would shine and keep me motivated until the next firing. And I had to keep making, not give up, keep optimistic with all those warnings from wood firers ringing in my ears - ' you learn to love brown'   'don't expect the public to to love it'  'you'll smash more on the spoil heap than you'll keep', blah blah blah but how true.
And then from the ashes of the final firing, 2 days before taking the work to Edinburgh for shipping, a piece which rings all my bells and ticks all my boxes and sent a shiver up my spine......

(haven't even got on the plane yet, we'll get there eventually)


 

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.

Rebuilding the kiln

The broken shelf which curtailed firing 16 gave me a chance to assess the. Condition of the kiln after 15 full firings. I removed the broken pieces of the shelf but couldn't get a whole new one back in it's place. The brickwork has shifted quite a lot with all the expansion and contraction of the firings.

 I had to unbuild most of the kiln anyway so I took the chance and went right down to the base. I had been concerned that the bed of sand on which the whole kiln sits may have eroded away.  But no, that is as good as new. What I should have been worried about was the chimney.
You can see the gap of about 2cm down the left hand corner of the chamber.
The internal chimney wall was listing away from the chamber and in danger of collapsing into the flue. As this wall is free standing it seems inevitable that this will happen and I'm lucky that the floor shelf went first.

These are fire bars at the rear of the fire box,  pretty well fused by ash, embers and the effects of the soda going in that way. All the soft brick back wall of the chamber was also very crusty. Time to reassess the soda?  The soft HTI bricks don't like it. I rebuilt that part using all the spare hard fire brick I had, taking some from the front of the fire mouth.

The chimney wall is strengthened by laying the bricks flat and increasing the size of the pillars on which they stand even though this reduces the flue area, and by tying the top course of brick into the side walls of the kiln. The chimney is also taller than the original design by 2 courses which takes the smoke away more effectively. Two firings later and it doesn't seem to be affecting the firing except perhaps for the better. It seems to climb more smoothly but perhaps that's because I've learnt not to get distracted.
The cooling has slowed down now that the new iron framework holds the fibre more snuggly to the walls. The iron is a little flimsy and will need modifying but it works well enough, especially the door.
All in all the rebuilt kiln is an improved one but I'm not sure I want to rebuild it every 15 or so firings. And of course it's just not big enough.........
I was at Aberystwyth a couple of weeks ago for the International Ceramics Festival. Had a brief chat with Joe- Mr Kiln -Finch.........

Firing 13 - lucky for some

But not for me!

Work to go in 

7am, 90oC after 2 hours, turn up the gas, cup of tea, breathe deep

Gorgeous day, Nice, easy and steady climb to 1200 then 15minutes of lost concentration and I never got it back above 1180. I knew the cones were telling me to keep going but after 13 hours the lure of fish and chips at the pub was too great (and there was a bit of applied pressure from R pushing me in that direction).

Lesson learned - instead of only another 2 hours to get to temperature I now have a whole 13 hour firing to do and on my own as R will be away. I think I'll go to 15 hours just to be sure. Have to say I'm hacked off. Not getting enough results to feed the passion. And to continue the misery, the kiln is showing distinct signs of ware, but that's another blog

Orton 7 8 9 & 10, obviously underfired, 9 should be well down

 However, I look at the photo of the sunrise and find there the consolation. 

Firing 13 in the planning

The frustration of not firing for a couple of months is getting to me. I find that I start to lose sight of what I am aiming for in my work. This time I am planning to fill the kiln with about 50% sell-able wares and fewer but more focused test pieces.

 We took delivery of the new iron framework (Caledonian Sheet Metal works in Inverness).  The kiln now has a detachable firemouth door and vertical supports at the corners. This should minimise some of the movement from firing and unbuilding for packing.  I suspect that a complete rebuild will be in order next year, at which point I might as well increase the size, it just isn't big enough.

 The door is a sandwich of fibre/kiln shelf/fibre, tin foil and weldmesh on the outer face. Two pieces of vermiculite board on the side which I dismantle for packing. We'll see how well that survives over time.
Isn't it smart? But......

Daylight between chimney hood and roof as the filler has burned out, letting the rain in of course.

Wood firing in Bohemia

chimney end of kiln

tall chimney

I haven’t fired my kiln for a while because I spent 2 months of the summer in the lovely Czech Republic, southern Bohemia to be more precise. However it wasn’t an entirely wood fire free time. Just as we were leaving home the postie delivered the latest issue of the Log Book (www.thelogbook.net) with an article about wood fire kilns in the Czech Republic. Talk about good timing. 

Side view of chimney showing damper and 2nd ware chamber
With a little research I learned that one of the potters mentioned, Martin Hadrava, was only an hours’ drive away from where we were staying in ČR.  So with some help from a Czech friend I got in contact with him and he was very welcoming and invited me to visit the next kiln firing. This was to be the inaugural firing of a new ‘smokeless’ kiln designed by Masakazu Kusakabe (see the book Japanese Wood Fired Ceramics by Masakazu Kusakabe and Marc Lancet) who would be there to oversee the firing. All very exciting as I saw him demonstrating a small version of this kiln at Aberystwyth in 2009. This is the largest version of the kiln which Kusakabe has designed. I don’t have the dimensions but you’ll see the scale of it from the photos.

Door to ware chamber, side stoke hole and fire box
Martin is based in a village called Klikov, near Suchdol nad Lužnici in the east of Southern Bohemia. The village is a traditional pottery village and I saw at least 5 kiln chimneys as we drove around looking for the new kiln. (Martin still uses one of the old wood fired ‘Kessel’ kilns, after a German design from about 1850, which he renovated, see more at www.klikov.net and www.hadrava.net ). We followed smart new signs across fields to a pottery which turned out to be closed, but we got directions and eventually found some open ground just outside the village with a couple of sheds and a big chimney. No point looking for smoke, all that indicated the presence of a kiln firing in process was a heat haze at the chimney top. Amazing considering that when we arrived the kiln was already at 1260℃. 

fire box mouth

There was quite a crowd, some directly involved in the firing process, some like me just wanting to observe. My two non potting friends who came with me were quickly drawn into the underlying excitement and anticipation of the process. I don’t think they had understood before how elemental it can be, a glimpse into the fire box was enough! I was there to see the draw rings pulled but didn’t get close enough to hear the discussions . The decision was made to continue firing. And at this point I had to leave, reluctantly, but decided to return for the unpacking a few days later.

For anyone interested here's the firing log for the anagama firing last week

Anagama Firing with Shozo Michikawa at Higham Hall

19th - 22nd July 2010

9.30am Monday. Light fire in ash pit, smokey,

1 10.30am flames being drawn up into kiln, place some wood into

fire box but continue stoking in ash pit.

2 11.30 some smoke from chimney, strong flames in fire mouth, cease

stoking in ash pit. Mix of pine and hardwood

3 12.30pm 490°C Pyrometer now working! Rake out ashes, reduce mouth

of ash pit to increase draft.

4 13.30pm 600℃ Raining

8 17.30 880℃ Still raining

9 18.30 970℃ Breeze blowing directly into the fire box

10 19.3 960°C Everyone present for the first reduction - lots of wood into the

kiln and then close the door over the fire mouth to decrease

oxygen in the kiln. Lots of smoke and dark red horns of flame

from the spy holes over the ware chamber.

11 20.30 990℃ Bit of a party going

13 22.30 1000°C Darkness falls, stoking mostly pine, some hardwood

23.55 1020℃

15 00.30 1005℃ Drop in temp after big stoke

16 1.30am 1040℃ Tuesday, first chimney flame visible.

17 2.30am 1050℃ Much quieter now

18 3.30 1065℃

19 4.30 1080℃

20 5.30 1090℃

22 7.30 1100℃

24 9.30 1120℃

30 15.30 1130℃

33 18.30 1120℃ Sushi interlude

34 19.30 1140℃

38 23.30 1140℃ Pizza. Stoking little and often

39 00.30 1160℃ Wednesday

41 02.30 1160℃ Deep roaring in body of kiln, good chimney flame

42 03.30 1160℃ Running low on wood, heavy stoking to maximize reduction

04.00 Last massive stoke

04.15 Final stoke, one piece of wood each, close dampers fully, clam

up ash pit.

43 04.30 End of firing, daylight.

Pots from firing 10

Detail of standing stone

small pebbles and standing stone, dia 10cm

cutlery drainer and dish, ht 11cm

textured dish, dia 31cm

selection of mugs, ht 10cm

Firing 10

3 May 2010

Up at 5 am to put the gas on. I chose the right day to fire today. It's already daylight and the birds are just beginning to sing. No clouds on the horizon. Back to bed for a couple more hours.

2 7am 97°C Turn gas up. Still sunny but gusting from the north

7.30 157°C Large log in with the gas on it

3 8am 185°C Wood slow to catch fire

8.30 212°C Removed a half course of chimney bricks to allow wind to increase draft. Gas off

4 9am 440°C Oops! now romping away. Removed damper brick

9.30 532°C Slowing down, damper closed

5 10am 540°C

6 11am 690°C

7 12 noon 818°C First heavy smoke

8 1pm 1024°C First sign of reduction flame in chimney

9 2pm 1115°C

2.30 1150°C First soda into firebox

10 3pm 1169°C Second soda in

3.30 1190°C Third soda in. Cone 5 down

11 4pm 1208°C Cone 8 bending

4.30 1190°C Lots of fluctuation, 1224°C tops

12 5pm 1213°C Cone 8 down

5.30 1221°C Maggie arrives to view firing

13 6pm 1199°C Firing down whilst beginning to clam up the kiln.

6.15 1175°C Beer at 5°C

this firing included a cone 9 test glaze on the top shelf from Elizabeth Westman so I was trying to soak the kiln at top temperature to see if I could get the test to melt well. All cone 8’s throughout the kiln went down and there was a good melt of soda with some carbon trapping.

Image shows chimney brick beginning to sag out of line. Probably due to the bed of sand we used to even out the bumpy concrete. Rebuild will be required soon I think. You can just glimpse the test glaze at the back - black shiny, green where thin, good melt. Will get cone 9s for next firing.

Can't wait.

As I haven’t got a firing planned for the near future I wanted to write a brief description of the first wood firing. Not just the first in this kiln but my first ever. I hadn’t even helped or watched someone else’s firing. My college experience all took place on the third floor of a central London art school building, no wonder they didn’t encourage woodfiring. The closest I have been to a full firing was Joe Finch demonstrating a gas/wood firing for the Scottish Potters in 2007.
After building this small kiln and reading various books and articles I still wasn’t confident but there came a point in late spring when I was on my own at home and I thought ‘I’ve just got to do it and to heck with the results’.
I packed the kiln with oddments and experiments and shoved my raku gas burner into the fire mouth to dry the kiln out slowly for 2 or 3 hours (the west coast of Scotland has high humidity). I planned to fire to cone 6 to start with, not knowing how long it would take, but I put cones 7 & 8 in too, to be safe. And I thought I would bung in some soda too for effect.

5am the next day with the sun already rising behind the mountains across the Sound, I stumbled out of bed to relight the gas on low. Having no idea how long it would all take and because I was firing solo I had decided to go up to 250°C with gas (which meant another hour back in bed).
7am I was back at the kiln with cup of tea, turning up the gas.
8am I started feeding in small pieces of wood along with the burner.
8.30 larger pieces started going in
9.00 gas was turned off and silence descended apart for the birds singing and the crackle of wood burning. I fed another piece of wood into the fire and the peace felt as wide as the view. Now I know why I do this, I have a sense of completing the cycle which I don’t get from electric firing and almost get from raku firing but not quite.

The firing continued as with the subsequent ones. I put in soda soaked wood into the fire at about 1150 (about 500g soda) It was remarkably easy to get the kiln to cone 6 down so I continued until the pyrometer read 1250°C and cone 8 was bending at the tip on the top shelf. I allowed the fire to burn down a bit then bricked up the fire mouth and the chimney and retired.
The next day the temperature was at 250°C and by the evening cool enough to unpack. (After 10 firings I am trying to slow down the cooling by firing down to 1100°C and with extra panels of insulation). The results were pretty unremarkable but so exciting to feel the weight and density of the stoneware and follow the path of the flames in the markings across the pots

This was the perfect day. The sun shone warmly in a cloudless blue sky (no midgies (wee biting monsters)yet). A gentle breeze wafted away the smoke and nothing to distract from the feeding the fire and enjoying being alive.

Pots from firing no.9

Interior of the kiln from the side

You can see the build up of glaze from the soda on the bricks. The first firing gave them the most beautiful orange blush. I realised that I should protect them with a wash of alumina. I've no idea how long they will last or how viable it is to do this kind of firing in a kiln which has to be unbuilt to unpack.

I used about 500g of soda for this firing which went into the kiln at about 1170 C over half an hour giving the work a light soda glazing on their exterior surfaces.

These are the best pieces from this firing. Each of the pots has a transparent liner glaze on the interior.

Lidded terrine

ht 13cm

width 21cm

Casserole, makes a good coq au vin.

Slightly ovoid,

ht 10cm

width 23cm

Deep oval vessel

soda glazed

ht 15cm

width 20cm

Deep oval vessel

ht 15cm

width 17cm

Jug with no handle

ht 13cm

width 18cm

building the wood fired kiln

A few pictures of the kiln build. May 2009

The base of the kiln. A bed of sand under a layer of common house bricks.

Complete layer of high temperature insulation brick (HTI 26)

First course of HTI’s. Firebox mouth at front. (firebars lying to the right)

Fire bars in place, front and rear bricks cut to form ledges, small pieces of HTI as spacers.

Next 3 courses showing firebox mouth. Extruded hollow kiln shelves forming roof of firebox and floor of ware chamber.

Rear of kiln showing kiln floor, inner wall of chimney supported by cut bricks to form flue.

Position for bag wall (formed from cut kiln shelf balanced on edge).

View from above of chimney being constructed, one brick in depth.

Completed kiln chamber. Pyrometer hole can just be seen in the middle of the penultimate course on the long side.


Kiln shelves forming roof with 2 layers of fibre. End wall has been rebuilt to include loose half brick as spy hole.

I’d just like to point out that all the sunny pictures are from Skye in June!

The next step is to fire it, or read a few more books about it first.