Kiln Disaster

Well, this is a bit of a sad tale. I have unpacked my latest kiln firing, only to find that 2 of my very expensive Japanese Silicon carbide kiln shelves had snapped during the firing and collapsed onto the work below.

Not a pretty sight.

The second and thord kiln shelves from the top have both broken.

Even though we lost 3 shelves worth of pots crushed or stuck together. There were still some very nice pieces to keep our spirits up.

The bottom shelf was OK.

Despite the disaster, there were still a lot of lovely pots that came out.

There is some nice subtle grey carbon inclusion and delicate ash deposit on the unglazed surface of the clay body.

The collapse seems to have diverted the flame path a little, causing some parts of the setting to get hotter than usual. This resulted in some over-firing and running of the glazes.

When the pale celadon glaze runs, it forms a very nice emerald green pool in the bottom of the pots. I really like the whiteness of the sericite body, contrasting with the emerald green pool and the pale hazey grey of the carbon inclusion on the rim.

I get out my quality control hammer and start to process some of the sub-prime pieces. They go into the ball mill, where they are polished for a few hours. When they come out, they are used as hand made celadon porcelain gravel ‘jewels’ for the driveway and paths.

This is one of the over-fired bowls below. The glaze has started to run, but it is still really beautiful. The runs have a build up of fine white ash glaze crystals. The pot has remained startlingly white, even with the wood ash attack. The glaze stopped just short of sticking to to the kiln shelf. What I find amazing, is that the sericite is so translucent at this higher temperature, that I can not only see light through it, but I can see the runs of glaze on the out side of the pot from the inside!

This doesn’t happen very often. It also has a beautiful, intense, emerald-green pool of celadon inside the base.

Its a really unique piece. You can even see the pink colour of my little finger holding the base of the pot on the other side, underneath. That is translucency! I’ll probably show it at Kerrie Lowe Gallery in November/December, in her Xmas exhibition.

I have kept one really translucent, but damaged bowl on the window sill in front of my wheel for inspiration. It’s ruined, the rim was destroyed when the kiln shelf on top fell on it and it is warped out of shape from the pyro-plastic deformation at the high temperature of 1300oC. Luckily, I was able to prize it off the bottom of the kiln shelf in one piece. It is so white and translucent, it’s an inspiration to me to see what is possible with this special ground up rock style of clay body called sericite.

I try not to think of the hours I spent working on it, turning and trimming it over several days, in various sessions, until I got it down to an even 2mm thick to get this result.

27 Kilns in 27 days – vol 3

Vol. 3. Recent industrial wood fired celadon tunnel kiln.

While in the Longquan traditional celadon region researching celadon, we took some time out to visit a former celadon factory, that was forced to close when the economy was modernised. It has now re-opened as a celadon museum/cultural park.

I found it a bit shallow and lacking in depth. That is to say what was there didn’t grab me. It may be of interest to the more general tourist, but there wasn’t enough there to speak to me, as I’m interested in the more intricate details and technical information/insights that could be included, but weren’t.

However, there was an old wood fired tunnel kiln that had been restored. This kiln was the main means of firing the celadons here right up until 1998. One can understand why it went broke and couldn’t compete with more modern factories with up to date facilities and equipment.

There was also an clay processing section that used the old fashioned water-driven, wooden clay hammers, that is a technology that dates back 1000 years. It was exactly fitted with the age of the kiln technology, So out of date for a factory setting, it is hard to believe that it managed to last right up until the 1990’s.

Clearly, this equipment hasn’t been used for many years, possibly since 1998? Just like the kiln.

All the pots produced in the wood fired tunnel kiln, were packed in saggers to protect the ware from the fly ash from the wood fuel, which is so important when making a subtle glaze like celadon.

It is interesting to see that sometime between 60 and 20 or so years ago, they wrapped some parts of the wooden roof frame with ceramic fibre to stop it singeing or charring during firing.

The saggers that were used in the kiln firings are these days used as retaining walls and breeze way walls.

27 kilns in 27 days. vol 2.

Vol. 2. The Long Quan Celadons

We take the bullet train out of Shanghai for the three and a half hours trip heading South West. We arrive at Lishui station and wait for a cab. There isn’t much at the station and the crowd that we arrived with soon disperse, but are soon replaced with another hoard of people from the next train. They all swirl past us, coming through in waves every 10 mins. There are just so many bullet trains passing through here with astounding regularly. It’s hard to believe. This is a very popular service. It must be on the way to somewhere more important, because this place isn’t anywhere in particular, that I’m aware of. But with 1.4 billion people needing to get around, even if only a small fraction of them live and work around here, it is keeping this service very well patronised. 10 years ago there were very few of these super-fast trains in China. 20 years ago there were none.

These days you can get to near almost anywhere quickly using this service, but mostly on the eastern side of the country. The government has produced a miracle in building this high speed rail system so extensively and quickly. Half of it is bored through the mountains in tunnels and the other half is suspended on concrete pillars above the valleys. It’s a masterpiece of engineering and it appears to run like clockwork. We comment on how Australia takes 5 years to make a 3 km road tunnel across Sydney. While the Chinese are building 3km of high speed rail infrastructure per day here.

Here in Lishui, we are about an hours car journey from our destination, as we wait for our car to pick us up. We try the local station food. This is just OK, not what I would usually want to eat, but I’m in a foreign country, so it goes down a treat.Anyway, there is only one choice. It’s a bowl of monosodium glutamate clear soup, with some fried tofu skin, 2 very small dumplings, a couple of dreadfully, scarily, luminously, bright pink ‘sausage’. I use that descriptor very loosely, and this is brought to life with some really great, bright red, slices of HOT, I mean very hot, chilli. A few drops of oil, some pepper and a lot of salt. It’s fantastic! I love it, but I try not to think about what was in the bright pink, extruded, sausage-like objects. I’ll never know. But when in Lishui, eat like a Lishuan! It was delishuious.

Our car arrives and drives at a little bit scary high speed to get us to our hotel for the night. We settle in and have a dinner of stirred vegetables. Soya beans and onion, mushrooms, fried tofu, steamed and then stir fried green beans, something brown that I don’t recognise, either in shape or in taste, which is quite bland and finally some little, green, mild chilis. something more akin to a small capsicum. It’s all delicious. but there is a lot of it, so I pass on the steamed rice and the soup.

The next day we are off to see the local Longquan Museum of celadon history. Longquan was a centre for the production of Celadon wares for several hundred years, from about the mid 900’s, through to almost 1600 – and it still is an important producer of high quality ceramic Art wares based around celadon.

Apart from Celadon, they also have some Guan ware and something that looks suspiciously like Ru ware, but can’t be, because Ru ware was only made in the Northern Song Dynasty. We’ve been tipped off, we have some local information, about an important new archaeological site. We spend our time dutifully taking in as much as we can in the Museum. But more importantly for me, there is the recently excavated archaeological site. I want to get some understanding of the early celadon manufacturing in these surrounding valleys. I have my pet theories, the possibility of seeing this site takes preference for me over other possible things to see and do while we are here.

The site is a half hour drive out into the country side. We wind our way out into the hills away from the fertile valleys. This is all very familiar to me. Even though I have never been here before. It is the same story. I can see it all unfolding. It has the ‘look’ that I recognise. These fertile valleys were colonised for food production first and pottery came later. The potters had to make do with the hilly surrounds where food production wasn’t a premium.

This is the same story or scene in so many other places where I have been researching in China, Japan and Korea. It also just happens that there are useful minerals to be found exposed in the wash-away edges of the streams up in the hills. This liminal country is very rich in feldspathic material I can see that from the car window. I’ve seen it all before. I call out to stop the car at one point. I say “We must be getting close now”! I can see out of my window, that we are passing a deposit of kaolinised porcelain stone. This is the local geology writ large in the road cutting. I recognise it from all the other deposits that I have studied over my lifetime of fossicking for porcelain stone and glaze rocks.

A pale vein of kaolinised feldspathic mineral, exposed in the road cutting.

If this is the local geology, of course someone would have been inquisitive enough at some point in time over the very long history of human occupation of these vallieys, to just pop a bit of that paler stuff into the existing pottery kiln where they were making earthenware and then later, stoneware, until finally they made porcelain. But it was only because the ‘stuff’ was here and available on site. No sericite and kaolin, no discovery of porcelain. It’s that simple.

The story is much the same where ever it happened in several different sites in a few different countries. If the suitable material was there, exposed near the surface, then it happened. If you are a potter, or several generations of potters. You can’t not make it!

We drive on, eventually reaching the dig site. All digging has now been completed and written up. There is a sign that tells all – but it is mostly in Chinese script and I can only decipher a bit of it using my phones translation app. But this is of little or no consequence, as the signage has a small section of English translation. How very thoughtful! Anyway, I’ve been in this situation before, and I know what I’m looking for and what I’m looking at in the most general sense. I can see what I need to see. As we wander the site for an hour, even making our way down to the small runnel of a stream at the bottom of the hill. There are even a few bits of broken shards in the water, all ground and polished into rounded edges of pale green celadon and off-white/grey-olive, guan-like glazes.

The story board tells us that along this stream was once a well-worn track along the banks that is mentioned in old documents. The finished ceramic work was carried out of this valley along here. We make our way back up to the kiln site. It’s a long tunnel kiln – or was. Only the base is left now. This site dates from 1000 to 1300. There are several layers of occupation/development on the site. The kiln has been partially excavated to reveal at least 3 layers of different kilns on the site over time. This site is called “Fengdongyan” and is 4.5 kms up stream from the small village of Daoyao. Daoyao village is where there would have been other potteries at that time. This higher and more remote pottery site was an ‘official’ government sponsored site. So it must have been important. Or so the info board tells me.

To extend my earlier proposition of the thesis that potters migrated up into suitable nearby valleys, Actually, I believe that they were pushed out by the farmers. I propose that the potters were originally farmers, who grew crops and made pots part time. Pots made from mineral rich clays from the valley floor. Something akin to red earthenware, fired in bonfires, or simple up-draught kilns made from mud, straw and shards. Over eons of time the space on the fertile valley floor became too precious for pottery making and firing. The potters who had by now become specialists, were relocated off the fertile valley floor and the now well developed paddy fields and their sophisticated watering systems.

the stepped tracing of the steep slope of the pottery site.

The potters now finding themselves on higher sloping ground, built their up-draught kilns into the sides of the slopes, becoming more like cross-draught kilns. This resulted in them achieving higher temperatures much quicker and with ease. The clays that they were close to on the slopes and valleys were better drained with certain fluxing minerals leached out. The clays became less fuseable, lower in iron and more refractory, needing the higher temperatures that were now possible, so paler stoneware bodies were evolved. etc, etc. Eventually semi cross-draught, down-draught tunnel kilns were developed because of their greater fuel efficiency and ease of achieving the higher temperatures. The rest is history!

When sites with porcelain stone were located nearby, in these valleys, it is impossible for me not too believe that someone like me, an inquisitive potter, could have resisted trying out this new white material. It needed a bit more work to get the kiln to mature it, it needed to go in the hottest spot, but it was possible, and therefore, at some point in time, it happened. The same porcelain stone body used for making the pots, could be mixed with limestone or wood ash and this now became a proto-celadon glaze that could be raw glazed, it’s that easy! It could be done, so it was done, it’s still being done! You only need 2 materials. Later, saggers were developed/employed to maximise packing and firing efficiency, but also to keep a lot of the wood ash off the beautifully refined glazes. Of course it didn’t happen over night, it took centuries. So much experimentation by generations of potters, each adding just a little refinement to the overall knowledge. That’s my thesis. I believe it. What is missing here is a clay supply. Why, this place so far up the valley?

When we were finished looking at this early Long Quan celadon site, we made our way back up the hill to the road, and on the other side of the road was a short track, that I hadn’t noticed previously, this led to an ancient mine site of very friable, crumbly weathered porcelain stone material. So this is why these potters migrated up here, 4.5 kilometres up this valley, away from the village, into this more remote spot, between 600 to 900 years ago. Now it’s obvious to me. They came here, all this way, simply because this is where the best material was to be found in its easiest, most workable form. No crushing required, just washing/blungeing, settling and stiffening. It all makes perfect sense to me. I’m dying to step off the walkway and go in and steal a little sample for analysis, but I resist the temptation. I’d put money on this stuff being a mix of sericite and silica, perhaps with a small amount of kaolinite or something similar. But I’ll never know!

In a way, I don’t need to. I already know. It’s just like every other site in a general sense. This place would fit very well into my book of ‘5 Stones’, except that I’ve already finished writing it. Every one of the 11 sites I studied in the 5 different countries, all fitted the pattern in some way, and every sample that I collected and and had analysed, with only one exception, contained sericite mica! That exception is Mittagong, where I live, where the mineralogy is similar but the mica is in the form of illite not sericite.

The mine site is quite extensive, it goes in two directions. I might imagine that they simply followed the softest, most plastic, easily dug material. I can see 300 years of potters endeavour, scratching out this hole here. It all makes so much sense to me.

I’m feeling really chuffed. This has been a really rewarding day. Even if nothing else happens on this trip. It has already been completely worthwhile for me.

Vegan Wood Firing

It is a beautiful clear, sunny day here today. The air is cold and a little fragrant. I’m not too sure what with, but it is crisp and refreshing. We have been up to Sydney and back for the opening of the wood fired show, at Kerrie Lowe Gallery, where we have our work on show.

This is a small white tenmoku bowl with a lovely soft ash deposit on the fire face, showing grey some carbon inclusion on the body and rim.

A very delicate and beautiful object.

  

These are two of janine’s blossom vases. These two vessels are inspired by Korean ‘Moon’ jars. On this occasion, Janine has incised a sgrafitto, carved band illustrating the phases of the moon, as a way of linking these beautiful pots back to the origin of their inspiration in Korean, where we have spent a bit of time recently doing our research.

These pots were fired in just 4 hours in our small portable wood fired kiln. This little kiln is so environmentally friendly that I call this type of firing ‘Vegan Wood firing!

All the fuel for this kiln is collected from wind falls in our paddocks. Large old eucalypt trees are constantly dropping dead branches. We have to go around collecting these dead branches to keep the ground clear so that we can mow the dead grass. We have to mow, because in summer, high dead grass is a severe fire hazard. So part of out land management plan is to keep the ground around our house clear of fire hazards, as we live in a very bush fire prone area.

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Having picked up all these dead branches, it seems irresponsible not to use them productively. By firing our wood kiln with wind falls, we are not hurting the trees in any way. No tress were harmed in the making of these pots. Hence ‘Vegan Wood Firing’. As we only use what the tree has rejected and finished with. It is also worth noting that some of the carbon that we collected from the atmosphere through the trees that we have grown here over the past 40 or so years is now encased chemically in our pots, making it securely trapped, more or less forever. So we are doing our bit to reduce the carbon load in the atmosphere. Carbon sequestration and removal on a personal scale.

We each do what we can.

Winter Wood Firing Workshops

We are very busy all this month with our winter wood firing workshops. We run these every winter, and it has become a reliable part of our income. We will be doing 4 firing workshops this month. We are currently half way through the series. 2 down and 2 to go.

So far we have had some of the best workshops that we have ever held. Excellent results keeping the students very happy. AND a zero rate of losses so far. Pulling red hot pots from a kin at 1,000oC can be challenging. The clay has to be of the right kind and the firing just right. Fortunately, we have a stock the very fast firing and fuel efficient small portable wood kilns that we build in our kiln factory, on-site. We have a number of these at our disposal these days. They work remarkably well, they are a joy to work with. We take about an hour to fire them up to top temperature from cold for the first firing. The work is unloaded using metal tongs. All the participants must be wearing flame resistant clothes, such as woollen material and leather boots or shoes to take part. they must also be wearing long leather gloves when working around the kiln. The hot pots are placed in a bed of damp sawdust to reduce cool slowly. This reduced atmosphere within the saw dust bed causes the clay body to be reduced to charcoal black colour that gives the fired work a distinctive contrast look between the shiny coloured glazes and the matt black clay body.

3 to 4 of these little amazingly fuel efficient kilns are sufficient to fire the work of about 10 students, as the kilns cycle through the day. I have built a few different shapes and sizes , so that we have a taller chambered kiln and a wider setting kiln as well as a cubic  chambered kiln, we manage to get through all the different shaped work in the day.

The kilns are reloaded with new work and left to sit in the residual heat of the kiln for 5 to 10 minutes. This allows the barely warm pots a chance to assimilate the residual heat from the kiln structure, before we start to fire the kiln up again. The subsequent firings only take 30 minutes, as the kiln is already hot, usually around 400oC when the recommence stoking. There is usually just a few small embers left in the base of the fire box, just enough to rekindle the flame and get the kiln going again. As the day progresses, the residual heat in the kiln is increased and there are more retained embers in the fire box. It makes for a very intense series of firings and unpacking. As each kiln and its firing crew work at different speeds with different loads of varied ceramic objects, all the firings and unloadings become scattered in to a series of repetitive, rhythmic ins and outs.

The day ends with a period of pot washing and scrubbing to get the work clean and shiny before packing back into their wrappings, stacked back into their vehicles and heading home.

It’s a very busy day for us starting at dawn, wheeling out the kilns in to the open and getting them ready for firing, stacking wood into wheel barrows, setting up pyrometers, preparing kiln shelves and wads, collecting kindling and setting up the outside coffee and tea table with electric jug and urn, etc. Its intense, we are glad to be back inside by dark, with everything packed away safely and all the surrounding ground watered and raked over to make sure that there are no stray embers allowed to start to smoulder. After dinner and again before bed we make our way back down to the firing site to check for any thing that might have managed to evade our watering can.

Sericite Journal 3 – Ashes to ashes, dust to glaze

While my work dries and I wait to pack the bisque, there are a few people and places I need to catch up on. I’m invited to both a lunch and a dinner with the students and staff of the Museum on two different days. I love Korean food, everything comes with chilli, even some sweet things!

After we have finished eating our lunch, it’s time to settle down and help the residents of the Baekto Porcelain Village make a thousand glaze test tiles. Everyone gets involved at different times. Many hands make light work and they are all made in one day.  

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I’m not really part of the group and I’m not too sure how I can help out in an unobtrusive way, so I decide to do the picking up off the floor of the cut sections and place them within reach of the real workers who know what they are doing. Later, having shown interest and done my time on the floor. I’m promoted to press-moulding the curved sections ready for assembly.

Before leaving the village, I wander up to the kiln shed to check out the kilns and I see 4 pallets of 2nd hand fire bricks, all cleaned and wrapped and one pallet of new firebrick slabs. I quickly calculate that this is about 2,000 bricks and 90 slabs. I’m guessing that these have been purchased for the kiln building workshop that Mr Jung has proposed to me. It may take some time to eventuate, as there doesn’t seem to be a a floor slab or roof for the kiln as yet.  

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I am scheduled for a meeting with Mr Jung and The Premier of the County of Yanggu, or State President, along with Myeongki Shim, the translator who has worked with me in the past and did the translation of my book, 5 Stones, into Korean. We are scheduled to meet on Friday to discuss the idea of offering a workshop style summer school open to potters to come and take part and learn about the down draft firebox in the process. I can see this taking some time to organise. 

It might not be the lack of a slab and roof that hold things up? Political realities being what they are, and money being hard to come by. We’ll have to wait and see.

I’ll need to do some calculations to get the whole thing to work correctly, as all the bricks are solid, hard fire brick, so this will limit what I can achieve with just one simple fire box. I’m also told that they don’t want to use ceramic fibre here for the lightweight firebox stoke-hole door, so there goes the idea of a top loading firebox lid and a throat chamber lid. It is starting to look like I might be building quite a small kiln, as I want to build and demonstrate a simple example of a single firebox, single chamber kiln that can be fired fairly cleanly in one day. Something in total contrast to the week long firings that take place in the traditional 5 chamber kiln that they have here.

The water wheel is working today, as Daewoong the resident wood fire potter, is keen to prepare some porcelain stone by the old method of using the stamp mill to crush the sericite. I’m unsure what he is planning, it could be for glaze instead of body material. Time will tell.  

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I can see across the valley to the new solar power farm that has recently been installed to generate solar electricity for the village. The admin block here was already covered in Solar PV panels, as is the Museum roof. It is noticeable to me that the new solar farm hasn’t taken any usable flat ground that was already used for farming. They have chosen to use the slope of the hill to get a good azimuth angle to the solar rays and not upset any farmers by taking over fertile, flat, productive land.

There has been a firing going on in the big gas kiln all day. The kiln is used by the residents in the porcelain Village. They can book the kiln individually, or as a group firing. They only have to pay for the gas consumed. As I understand it, the residents get free rent of studio and housing spaces, plus free use of the equipment like kilns, wheels, slab roller and pug mill, etc. They only have to pay for their own food, heating, kiln fuel and any exotic raw materials that they may wish to pursue. It seems like a too-good-to-be-true deal from my point of view, as an outsider from Australia, where the Arts are more or less ignored, or if acknowledged, they are mistrusted and/or miss-understood by the general public, encouraged by the Murdoch press, and any money spent on the Arts is roundly ridiculed by the conservatives. No wonder the facilities here are all full. It seems that the locals think that this is normal and complain about having to pay their own heating bill!  I couldn’t get a room in the student accomodation building this time round. Everything is fully utilised, so Mr Jung has kindly offered to allow me to stay in his home with him, 30 minutes away in Yanggu.

When I get to the Museum and Research Centre the next day. The bisque kiln is ready to be packed. My work is all completely dry now. I take it over to the kiln room for packing. There are 2 large electric kilns used for bisque firing on a regular basis. These are used to fire the the part-time students work from the teaching facility.

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My work is slotted in where it will fit among the regular student projects. My work isn’t large, so it can be fitted in economically. I nest stack them to conserve space. I start with a 5 high stack, but I am discouraged by the technical assistant/pottery teacher. He seems to indicated that with this clay, its particular dry strength and firing characteristics, it is better to just go 2 high, so I do. The firing goes on over night using a ramp programmer. It’s all very modern and efficient in this regard. However, in contrast to this, they also have a 5 chamber traditional wood fired climbing kiln as well for the wood firing enthusiasts. We took part in a 4 day firing of that wood kiln the last time we were here. 

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While my pots are cooling down from their bisque firing. Mr Jung arranges our us to go on a     geology expedition up into the mountains behind Yanggu. There are some logging tracks that we can use to get us up there quickly. He tells me that because he was born and grew up here in the foot hills of these mountains, he has tramped over most of it through the years. We swap his LPG-hybrid, city sedan, for his parents small 4 wheel drive, and set off. He wants to show me a couple of sites that he thinks might be worth our while investigating. 

After a slow and bumpy 45 minute drive over the rough logging tracks, we arrive at the first of what turns out to be 5 sites. This material looks to be a weathered or kaolinised, fine to medium grained acid rock with some small amount of free silica. It’s impossible to say what is in it, but I can hazard a guess that it has some sort of primary clay such as Kaolinite, Halloysite, illite or dickite. It also has the obvious spangles of some free silica that is just visible in the bright sunshine, then there may be some flux minerals such as the felspars or micas, if they haven’t all be weathered down to the clay minerals. The stone is very soft and easily broken up by bashing it together, so I’m certain that it will be low in flux and higher in clay minerals.

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The stone is so rotten, that the fragments are just tumbling down out of the hill side. To my naive geological eye, it looks pretty much like a lot of the material that I have collected back home in the Southern Highlands. It may be able to be finely milled to become sufficiently plastic to be throwable. But they already have a marvellous sericite body here that is beyond excellent, white, plastic and translucent. This new stuff won’t compete. I’m thinking that it might be possible to make a glaze out of it, but it looks a bit too weathered, kaolinitic and refractory to make much of a glaze with just limestone as a flux. I’m not sure, I get the feeling that it might need some extra felspar as well, and perhaps a little ash with it as well? 

I have no real concrete evidence for this thought, it is just what I have experienced back home in my previous research in Australia. The stones that are hardest to crush usually have the most intact alkali content and melt well. The softer materials that are very crumbly, have usually lost a lot of their alkali during weathering and are more refractory. Where this stone fall on the spectrum i can only guess at this point. I won’t know until I have fired some. However, my guess is that it will fall somewhere smack in the middle. Unmelted on its own, but forming a glaze at the end of the line blend series, requiring the maximum calcium flux.

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When we get back the the Museum a few hours later, I set to work making a few tests. I Start with a grid tile test to ascertain the chemical analysis. This is a unique test that I developed during my PhD. I involves producing a series of line blends with specific additions of a set ratio. The resulting grid tile when glaze fired, shows a particular range of melts and colours. By comparing the new material test with my data base of known and chemically analysed test tiles. I can deduce the chemical analysis of the oxides present in the new material to with in a couple of percentage points. It saves having to send the material off to the university chemical lab and pay a lot of money to learn the same thing.

Pretty clever I think, if I do say so myself.

Apparently. I am the only one who thinks so and says so. Everyone here watching me work, have no idea what I’m doing. but they keep an eye on me, just the same.

I also take a risk and follow a hunch and prepare a line blend in a series of 5 simple steps that I think will show some worthwhile result using this material as a body ingredient, based on my research on similar materials that I’ve worked with back at home. I’m guessing that it will be nice in a wood firing, but I’ll never know, as I only have sufficient material crushed and ground to made these few basic tests for the gas firing coming up. There isn’t a wood firing due at the moment.

I used a bisqueted test tile that I have brought with me from Australia in my suitcase to do such a test if necessary. I’m glad that I did, as there is no time to make one now and get it through the next bisque in time. I decide that I will only do the first three line blends on this occasion, as the last line will be too siliceous to tell us much about a stone like this one. Or so I think. I decide to use the remaining material to make the body line blend of 5% increments.

The next day, the bisque firing is unpacked and I start to glaze my work.  

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I get all my work glazed and fettled and out into the sun to help it dry out by early afternoon. The smaller and lighter of my bowls are quite delicate and thinly potted. So I can only afford to swipe them through the glaze in one second, so as not to saturate them. Otherwise the glaze will start to run off before it dries. I like to glaze all in one motion if I can, but these pots won’t have sufficient glaze on them to develop any depth of colour. So I decide to partially dry them and give them a second dip to create a thicker glaze coating. This carries a risk of causing pin holing and crawling, but I weigh up the options and decide to take the risk. 

I could choose to spray on a thicker coat, and that would work better, just as the ancient Chinese did a millennium ago, but I’m not from around here and don’t know if there is a spray gun available. There certainly is a compressor, as I’ve already used this once before to blow the dust of my bisque ware. However, I don’t want to outstay my welcome, by constantly bothering the staff, who are always busy, by asking questions, unless it is absolutely necessary. Of course I am incapable of asking any question directly. I involves the use of the translation app on our phones. It’s a slow process and takes up their time typing out questions and answers with one finger on the tiny virtual key pad.

There is a change in this regard this year. I’m asked to down load a new language app onto my phone. This is a new Korean developed translation app, and every one here is using it. It is specifically built to translate Korean. It handles spoken word input too, which speeds things up. There is a little hick-up here with this. My Australia Post prepaid travel SIM card doesn’t handle data. Only calls and texts. Data packs can be purchased for other countries, but not Korea at this stage. So it turns out that I can only use the ‘Papago’ Korean translation app. when i have WiFi service to log into. That really limits where I can use it.

The standard porcelain glaze that they have developed here looks to be made using some sort of ash, as it has a fine grey cast to it and a infinitely fine dark speckle in the dried surface. It just looks like an ash glaze. I can’t justify that opinion any more than that. The next time My Jung, The Director of the Museum passes by, I have my question already typed out on the phone. “Is this glaze made with ash?”. He responds to me in English, “tree ash?”, I respond “yes, tree ash!”. He indicates to follow him into the next work area. I haven’t spent much time in here at all. I have only just glanced as I passed. I have had no business to be in here. I try not to cause any trouble as a guest. A position that I am very grateful to be in.

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Mr Jung takes me to the ash preparation area. There are a series of very large tubs where ash is washed and sieved, then left to settle. In the settling tank, there is a rope suspended in the water. I must look puzzled, as Mr Jung the word in English, “magnet”. He shows me this by lifting it out by its rope and sticking it to the metal floor grating, which he demonstrates, he can now lift up out of the drain, just by the power of the magnetism. The big round magnet must be very powerful. He takes the magnet to the sink and washes it, and to my surprise, it is not big and round at all, but narrow and skinny. It was clustered with irony material stuck to it. I don’t know where all this iron came from, perhaps they burn the organics in a steel furnace?    

The cleaned magnet after washing off all the irony ash particles.

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Mr Jung then takes me to the glaze store room, where he shows me the working stock of dried ash that they make here. There is ash made from all sorts of plants. Mixed tree ash, Pine ash, chilli plant ash, chrysanthemum ash, ginkgo ash, even calendar flower ash! I’m stunned. So much work! I know what I’m looking at, because we burn plant material to create ash back home and sieve it and dry it. But not on this scale. I guess that it helps if you have a staff of 12 to help you get everything done. The biggest problem that Janine and I face, is that we are trying to do everything ourselves. We are getting older and not surprisingly, we get tired.

I wouldn’t mind a staff of 12 to help get things done. Not too sure how we would pay them though?    Actually, just a part time staff of one would be nice.

My glazed and fettled pots are now packed into the glaze kiln. They will be committed to the fire tomorrow in a 12 to 13 hour reduction firing to 1260oC. I’ll have to just sit it out and wait-n-see. 

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Sunshine Came Softly Through My Spy Hole Today

This is the research paper that I presented to the recent Ceramics Triennial Conference in Hobart, Tasmania.  On the ‘Sustainability’ Panel.

Steve Harrison – Sunshine Came Softly Through My Spy-hole Today.

I was raised in the 50’s in a home where the topic of ‘health foods’ and ‘natural living’ was at the forefront of conversation. I came from a loosely quaker/buddhist background with a grounding in ‘healthy’ living. As a child, I was brought up in this environment. Aristotle said “give me the child until he his 7 and I will give you the man”. I am that man. A ‘greenie’ before the greens were invented.

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Since I decided to be a potter, I have always been a wood firer using a small, single chambered, bourry-box kiln. I wanted to fire my pots as cleanly as possible, in an environmentally sensitive way. In 1976 I moved to the country and bought a very old derelict school building, built in 1893, with seven acres of land and started planting a forest. By growing my own trees, these trees took their carbon out of the air, when I eventually burnt this timber to fire my kilns, it didn’t introduce any new carbon into the atmosphere. This was the best approach that I could think of to minimise my carbon footprint at that time.  I’ve progressed!

We have also planted very large vegetable garden and 5 small themed orchards, with a dozen cherry trees, a dozen almonds, a dozen hazel nuts, a dozen citrus, a dozen stone fruits, a dozen apples, 5 avocados, 4 truffle oaks, 3 white figs, two berry vines and a bower bird in a pear tree!

My wood fired kiln has proven to be very fuel efficient, I have worked on the design for over 40 years and written the standard text on the subject. ‘Laid Back Wood Firing’ and it is as clean as a wood fired kiln can probably get, without using an after-burner. I tried adding afterburners to several kilns, but have since abandoned that idea as too wasteful and complex. There is no point in using a premium fuel like LP gas to burn the smoke from an inefficient wood fired kiln. I couldn’t justify it. So I stopped working on that project.

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I did a lot of work on ‘flame tubes’. Fibre lined stainless steel tubes on top of the chimney that allows warm air in at the base, so that it mixes with the unburnt smokey fuel during reduction and combusts with-in the tube. All that is seen is a pale red glow at the top and bottom. The beauty of it is that it has no moving parts, and needs no external fuel source.  The blue haze at the beginning of firings has always bothered me and flame tubes don’t fix that problem. That is a work in progress.

It is possible to fire in reduction at high temperature with very little smoke, but the cold blue haze at the beginning of the firing is a very difficult problem to overcome. It was only later that I came to realise that it isn’t just blue haze smoke at the beginning of the firing when we are releasing ultra-fine particles into the atmosphere from our wood kilns. Wood firing generates loads of fine particulate matter, all through the firing. Some of these are quite fine and are hazardous to inhale. They are known variously as PM 7’s to PM 2.5 particles, they are small enough to enter deep into our airways and lungs and can cause all sorts of unpleasant health effects, even cancer.

Clearly, one kiln, fired intermittently, isn’t the problem, but when it is added to the other emissions of diesel vehicles, wood heaters and industrial pollution from factories, cement works etc. It adds to and is part of the larger problem.

See the EPA web site.   https://www.epa.sa.gov.au/environmental_info/air_quality/assistance_and_

advice/smoke_from_domestic_heating.

Added to this less-than-up-lifting scenario, there is the growing problem of global warming. Contrary to the statements of conservative politicians and the hard right media shock-jocks, the science IS settled and has been for a long time. The man-made global-warming deniers are simply wrong! They are either being disingenuous or choosing to be ignorant. Perhaps I could be generous and say that they are choosing different truths.

We used to be able to fire for 8 or 9 months of the year at home, but over the past 42 years, living in the Southern Highlands, our window of opportunity for wood firing has been reduced now down to 5 to 6 months, May to August. September is now getting too unreliable to book wood firing workshops. We have had to cancel workshops in the past few years due to hot, dry, windy weather and therefore total fire bans, as early as September. Total fire bans in our area used to only occur in January and February.

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Some time ago, I decided to develop a series of small portable wood fired kilns that could be wheeled out, packed and fired in one day. Then wheeled back away again until the next firing. These portable little wood kilns are very fuel efficient and can reach stoneware temperatures in 3 to 4 hours using a wheel barrow of wood. If you are careful, they can be fired very cleanly. They are a fun solution to minimising carbon emissions and avoiding the use of gas and coal. By collecting fallen branches from around our block, we can fire with a zero carbon foot print. This is the ‘vegan’ equivalent of wood firing . No trees were hurt to fire the kiln. The trees drop the dead branches. We have to pick them up to mow the long grass. We have to mow to reduce the fire hazard in summer. So fallen branches do not introduce any new carbon and are tree friendly. That’s nice, and the kilns are quick and fun to fire. But particulates are still a problem.

So where is all this leading? I realised that I needed to find another way to fire my work cleanly and efficiently into this uncertain, carbon constrained, globally warmed, future. The climate is changing, so we must change with it. Janine and I have had solar hot water for over 30 years and Solar Photo Voltaic panels on our roof, for the past 12 years. We installed 3,000 watts of Australian made, BP Solar, Photo Voltaic panels as soon as we could afford to do so in 2006/7.

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Our first solar panels, with the netted vegetable garden with small vineyard and orchard.

We have been using our electric kiln for all our bisque, earthenware and oxidised stoneware firings ever since then and have always paid the little extra for sustainable green power since it became available. So that if we needed to draw power from the grid, it was sustainably generated power that we used. In the last couple of years we have been working towards firing our work in the summer months of fire bans, using a new low-thermal-mass electric kiln that I built from a pile of spare parts, left over from my kiln building factory, after I retired. I designed and built a kiln that is fired using our solar panels and backed up by our Tesla Powerwall II battery.

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To allow us to fire in reduction, I made allowance to install 2 small pilot burners in the bottom of the kiln and built a small flue hole in the top. These burners aren’t used to fire the kiln at all. They are too small. The kiln fires to stoneware on solar power, the burners are only used to create a very small amount of flame to generate the reduction atmosphere needed to change the glaze colours.   I attach the burners to the kiln and light them when the kiln reaches 1,000oC. They use about 200 to 330 grams of gas to reduce the kiln load of pots steadily over a couple of hours while the electrical elements heat the kiln load of pots. It’s the best solution that I can find at the moment to give us reliable, all year round access to reduction firings that are very, very, low carbon and as sustainable as I can make them.

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The firing can take as little as 4 to 5 hours in total and give perfectly adequate reduced results. Experience with this kiln has shown that we can achieve all the normal reduced colours with our standard local milled rock glazes. I fire the pilots on 5 kpa gas pressure, but have recently experimented with pressure so low that the regulator gauge can’t register the flow and the kiln still reduces. We usually wait to start the firing until around 9 or 10 am, as that is when the sun is up high enough to give us the energy that we need to get the kiln going. It takes about 2 to 3 hours to get to 1000oC, then I attach the pilot burners and start reduction, around noon to 1 o’clock. I reduce for about 2 to 4 hours depending on what I’m experimenting with and finish the firing between 2 and 4 pm. as the sun is going down. We fire directly off the PV panels until 1 or 2 pm, then as the sun passes its peak, and the kiln is drawing its maximum power. The Tesla battery cuts in automatically to make up the short fall to finish the firing. If the weather is cloudy we can also draw down on our credit with the power utility. As we are on a ‘net’ metering system, and are always in credit. We never actually ever pay for any power that we withdraw from the grid. However, it is important to note that we pay the extra to contract to only use green power from sustainable sources when we do with-draw.

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I don’t know if you have ever seen one of these graphs?   It is the screen from the Tesla mobile app that tells me how much solar power I’m producing and consuming and/or selling/buying from the grid.The yellow area indicates the solar power generated. As you can see the solar energy starts off low at 7 am, then from 10.00 am it quickly rises to a peak at noon, hovers for a while, then drops away until 6 pm. and sunset.The green area is the energy required to re-charge the battery from its use since yesterdays sunset and running the house over night. This re-charging is usually complete by 9.00 or 10 am.The blue areas of tiny upward spikes is the fridge turning on and off regularly over night and all through the day. The sharp blue spike is the electric jug and toaster being used at breakfast time. On this day it was at 7.00 am. The white area below the line is the energy that we sell to the grid every day when we are not firing the kiln or charging the car. This generates a credit that we can draw down on in cloudy weather and covers our daily charges. This report tells me that I generated 35 kW/hrs of solar and used just 1.4 kW/hrs to run our home and pottery on that day. We sold 32.8 kW/hrs to the grid. It was obviously a quiet day with nothing much going on. I wasn’t welding in the kiln factory or ball milling rocks and pugging clay in the pottery.

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This is what a firing looks like, We simply stop selling our excess to the grid and use it our selves. The blue block is the amount of energy used to fire the kiln. The taller blue spike on the left, is the car being charged at the same time. It is worth noting that we can do both at the same time and still recharge the battery after wards in the afternoon.

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Just as an aside, we also have a solar powered electric car. A Hyundai, Ioniq, ‘plug-in’ electric car. I have written about this on my blog on a few occasions with regular up-dates to let readers know how it’s going. v< https://tonightmyfingerssmellofgarlic.com >

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This is what happens when we charge our car. We simply stop selling our excess to the grid for 2.5 hrs. There is enough power to do this, even on a cloudy day, as is the case in the chart above.

We put our pots out in the sun to dry. We call it the ‘solar drier’. The solar drier makes sure that the pots are totally dry before bisque firing. We can charge the car as well in the back ground, both using sunlight at the same time! It’s amazing that there is enough sunshine to go around! The vegetable garden keeps growing and the orchard thrives! We can also walk and chew gum at the same time.

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To help make this all happen, we recently bought into a community bulk purchase scheme and installed another 3,000 watts of Australian built solar PV from ‘Tindo’ in Adelaide. This allows us to run our house, fire our kiln and drive our car, all on our own sunshine. It’s a very nice feeling to be able to live, cook, work and drive, powered almost totally from our own solar power. We do all this and still have a little excess to sell to the grid. This covers our daily charges to be connected and even earns a little bit of extra cash. I haven’t paid an electricity bill for 12 years. You can see from our recent bill that we do all this and still use about half of what a single person household uses, and much less than half of what a two person household like ours uses.

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Now, I know that someone is going to ask me what is the cost benefit analysis? It’s the most common question that I get asked along with the statement, “I wouldn’t put solar power on yet. you can’t make any money out of it!”Well, my answer is, when you bought your new car. How did you make money out of that? Or, when you flew to Bali for a holiday, How did you make money out of that?

The point is that I did this because it pleased me. I get a lot of satisfaction out of it. I did it to extract myself as far as is possible out of the coal and oil economy. I didn’t do it for money. I do very few things in my life solely for the money. I’m not very interested in acquiring ‘things’. This is the equivalent of my holiday in Bali, or my ‘walking tour of the vineyards of Provence’. I’ve never been to Bali, or walked the vineyards of Provence. We each choose to spend our discretionary dollars in our own way. This is mine.

Now finally, I will add that I bought carbon credits to cover the carbon off-set of my flight here. Real off-sets in the form of planted trees. I buy a few hundred dollars worth of carbon credits each year to cover all the damaging things that I do to the environment in my life, like air travel. I think that it is worth it. I’m not proselytising for solar. You will have already made up your own mind about that. You’ve had a couple of decades to consider it. I’m just telling you what is possible, because you won’t have heard it from the the Federal Energy Minister or any one else in the government. This however, may be food for thought, if you haven’t already though about it. I will end by telling you that the future is here and this just might be what it could look like.