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.

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

I won an award

In the middle of rebuilding, chopping wood, packing the kiln and firing it in 4 hour shifts for 40 hours in a place of limited mobile and wifi coverage, I learned that I have won The craft&design Selected Awards 2012: Ceramics, gold award.

 http://www.craftanddesign.net/awards/selected/

 'These highly regarded national awards, first launched in 2009, are based on an Online Public Vote for British and Irish designer makers with work represented in Selected, craft&design’s prestigious online gallery at  www.craftmaker.co.uk. The Public Vote determines six finalists in each of six categories. Specialist Invited Judges, together with the craft&design panel, subsequently assess the work of the finalists to establish one Gold Award Winner, two Silver Award Winners and three Finalists in each category, with just one person being awarded the top accolade of craft&design Maker of the Year Award.'


The only downside to this is that the lovely and wonderfully talented slipware queen Hannah McAndrew couldn't join me on the podium and had to settle for silver! But how do you compare apples and pears? Or jugs and bowls for that matter?

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.

Treasures at the Scotish Museum,

The Scottish Potters Association arranged a visit to the  National Museums Collection Centre ceramics department of the Museum of Scotland. Stored at two sites in Edinburgh, I was in the group visiting the English, continental and contemporary department in Granton. We were lead upstairs and downstairs, along corridors and through great hangar like rooms full of vast machinery awaiting conservation. Finally reaching one of the rooms which houses the ware. Cupboards lining the walls and in a central block of back to back cupboards which were unlocked as requested and left open for us to handle pieces the like of which I have only ever seen before in books and behind glass. 

 

 

I felt just like the little pot below.

English Medieval lead glazed cup, 4 inches high - I'm in love.

Some of this medieval work is so fine and lightweight. It looks crude and coarsely potted but it's not. It is beautiful in the hand and absolutely fit for purpose. I'm astonished by it.

Watering can, about 18 inches high

Detail of the handle

English 13th -14th century, buff earthenware, lead glaze

 This, above, was the most finely thrown of the pieces which grabbed my attention, with a slightly swollen base.

ditto, with impressed panels of deer, 20 inches high

We tried to work out how this one was constructed. The upper half has fine throwing rings visible, the lower half is distorted, possibly from the impression of the carved panels. There was a difference in texture inside the pot.
It was such a treat to handle these pots. The collections are public and the curators were very insistent that we come back again, that's what they are there for.

Pug Mill Blues

Pug mill blues

I have been tripping over 2 buckets of black firing stoneware clay for the past 4 months. As I am trying to convince myself that I am back in the workshop properly and full time after the festivities of winter I thought I would start by dealing with the black stuff. I like the fired colour and texture of this clay, dense blue/black, not as soft as the raku blacks but has the advantage of being stoneware and therefore will take water. Except that after my treatment of it, namely stretching bashing and wood firing, it tends to crack, dunt and leaks like a sieve.
I’m hoping that I can cure this rather fundamental flaw by mixing it with a more fine grained and plastic stoneware. I don’t mind losing a little of the black if I can produce a useable pot. I happen to have a large bucket of white St Thomas scraps, dried and soaked to a nice mush waiting to be reconstituted into throwable clay, and also a bag of unidentified firm stoneware which could be mixed with the black in carefully measured and documented handfuls until it looks about right. A couple of hours work by which time I will be ready to be Creative.

The black clay, anagama fired

I always leave a note of the last batch in the feed hole. I removed the plastic covers from the pug mill and turned it on to check the motor. Working but not happy.
I started to scrape out the nasty crusty iron stained scraps from the safety grid in the feed hole and discovered a nasty crusty iron stained safety grid. Better clean it up before putting more white St Thomas through to push out the remains of the last pugging, won’t take long. I think I have never taken out the grid since I bought the pug mill 2nd hand 3 years ago.

This grid is clean

 

 

 

The intestines of a pug mill

The bolts were seized so Non Potting Partner was called in to wrestle them off and pull out the grid. Whilst I cleaned that he dug out the hard clay underneath and found yet more hard clay.  


   


 16 bolts later the top came off, yet more hard clay and crusty corroded metal. Fortunately the screw which pushes the clay along, mixing and conditioning it was bright shiny brass (or bronze?) under all the nastiness just like the propeller of a ship. NPP, the old sea dog, carried on until all was ship shape and Bristol fashion (what?) as you can see from the dazzle in the photo.

With such a clean mill I had to pug the entire lot of white St Thomas before shoveling in the dirty stuff. So a little job to get me in the mood to unleash a storm of creativity ended up in dry dock for nearly two days to complete, and I am still scrubbing splashes of the black clay from decks.
(It won't stay this clean for long.)

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)


 

Firings 16 & 17

I'm writing this in the middle of the 3rd firing since the rebuild.
The first, no. 17 zoomed up to 900 in 7 hours (weather not a factor, overcast and light breeze) then stalled around 1100 for about 4 hours. After 13 hours I managed to coax it up to 1200. Where it stuck for another 2 hours reaching 1240 tops but acheiving cone 9 down.
The results included some lovely carbon trapping in a soda ash glaze I was testing.
For firing 18 I attempted to follow the previous cycle to get the carbon trapping effects again. The weather was breezy from the south west so not too different.
I reduced for an hour at 900 but not a heavy reduction, as the breeze was blowing directly into the firebox. The kiln stalled again between 1120 and 1170 for about 5 hours. Reaching 1218 tops but with cone 9 only just starting to go after16 hours, by which time I was completely gone, so clammed up and headed for a hot bath.
I then had to wait 2 whole weeks on an annoying holiday before I could unpack this kiln. That's the trouble with non potting partners they don't really understand what's the priority. Actually I did prize open the lid for a quick peek just to reassure myself it wasn't a disaster, that would have really spoiled the holiday.


I should mention here the benefits of non-potting partners - coffee, breakfast, lunch, dinner, cups of tea, that magnificent cold, cold beer at 6 o'clock with the kiln at 1200 Centigrade after 13 hours of continuous firing, all brought to me with barely a hint required.

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 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.

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.

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

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.

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.