Korean Sericite

A couple of months ago, Janine and I were lucky enough to be invited to Korea to speak at a Porcelain  conference. We made the most of our opportunity and spent time in Seoul on our way to the conference to visit friends. I also made the most of this once-off, free travel opportunity, to re-visit one of the remote Sericite Porcelain Stone mining sites in Korea. This site dates back into the 1300’s. Sericite Porcelain has been mined there for over 700 years. I have visited this site before during my research trips, so I don’t need to put on my Indiana Jones hat and consult the ancient parchment map to get there. I know the way, at least I think that I do. I do have trouble convincing Janine of this though when we come to unexpected junctions in the track. We are tramping with our back-packs and although I have found my way here before, we just take the time to walk up a few dead ends into the hills, and retrace our steps a bit, before regaining the correct path. I managed to find my way here after the last conference and re-discover the site. I know that I can do it.

I must say that even though I’ve been here before, it’s amazing how easy it is to forget all the details of the way when you are out in the bush. I remember all the twists and turns in the various tracks that I need to follow to get there, but over time, things have change and the bush has grown over some landmarks, however, there are enough clues that come to mind at each change of direction, so that from time to time I recognise specific points along the way and I am convinced that I am still on the right path.

Eventually we find our way there. This ancient site is pretty damaged now, as the stone hasn’t been obtained from here for some time. I don’t know how long, but perhaps a couple of hundred years. However, there is still a small amount of the sericite embedded in the ground. There had been some heavy rain since I was last here and quite a few good large chunky samples have been exposed, so that I had no trouble filling my small pack with a couple of kilos of good clean samples. I hand pick the best and whitest bits from the dross that it is mixed with.

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IMG_3095Now that I’m home and have caught up with all my other more pressing life events. I have time to deal with this most recent research. I set about crushing and grinding these new samples. Prior to this, I have only collected a few hundred grams of stone, purely for analysis and academic research. This time I have enough to be able to throw a few pots.

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Seiveing the fines from the crusher, before going to the mill.

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I put the stones through the jaw crusher and then the disc mill, then finally through the ball mill. If I had more to deal with I would put the slurry out on the drying bed. But as I only have a couple of kilos of material, I put in into the plaster drying tubs to stiffen up.

This turns out to be a really fantastically plastic sericite. I can wedge it up using spiral kneading straight from the drying tub with no ageing. Amazing for 100% milled stone. It seems that Sericite can be as plastic as any other ‘clay’ – even though it isn’t! (clay, that is).

I was very impressed with the plastic sericite from Cheongsong in south Korea. That was the best single stone porcelain that I had ever experienced up to that time. However, I wasn’t allowed to see the mine site or any of the processing that was carried out, so I couldn’t draw any conclusion, other than to say that the experience of throwing it was excellent.

This time I’m absolutely sure of what I have in my hands and on the wheel in front of me as I have collected it direct from the soil with my own hands and done all the processing myself. It is very slightly floppy on the wheel, but this is to be expected for a very pure primary ‘clay’ – ground stone actually, with no ageing. It certainly works infinitely better than an ‘Eckalite’ china clay body prepared under the same conditions. I’ve been there and done that.

I might just add here that I have a batch of ‘Eckalite’ kaolin based porcelain body that I made 25 years ago. It was un-usable straight from the pug at that time. Floppy and useless. However, it has been ageing in the cool dark clay store now for all this time and it is quite plastic to throw with now. As good as anything else on the market these days. I only wish that I had made 10 tonnes of the stuff back then. It would have been totally worth it. I don’t have 25 years left in me now, so it’s pointless speculating as to what might have been.

Any young potters out there interested in materials and porcelain. I’ve done the research for you. Make use of it.

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I have no trouble throwing it on the wheel, it is smooth, fine and creamy and stands up well for small items, keeping its shape and not slumping. If only I had discovered this stuff  20 years ago too! It would be amazing by now.

As far as I can ascertain, from what I have been told through translation. Nobody has used this stone for a few hundred years. It has almost archaeological significance, embedded in its remote, hidden hillside home. No-one in Korea has taken an interest in it as far as I can tell. There is only myself and the local Porcelain Museum Director who seem to have any fascination for ancient sericite porcelain. You’d have to be mad to go about doing research like this strictly for the sake of academic interest. It appears that I am that person who is mad enough. So I am going to donate the best of any successful pots from the firing to the Porcelain Museum for their collection. It will be the only pot made from this stuff for the past few hundred years. Here’s hoping that the firing is a good one.

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For an extensive discussion of Sericite porcelain, I refer the reader to my book ‘5 Stones’ which details my 16 year research into sericite porcelain around the world.

Thinking Differently, Solar Power and Clay Making

I usually spend a bit of time making clay over the summer when the humidity is low and the air temperature is high. It’s a good time for drying out the clay slip after it has been ball milled.

All my so-called ‘clay’, is actually ground up igneous stones. I crush the very hard ‘granitic’ rocks in the big jaw crusher first to reduce them down to 12mm. gravel size, then through the small jaw crusher to get it down to sand size and finally it goes into the big ball mill for a few hours to reduce it to a very fine slip with water and 3% of Australian white bentonite. It is the only ingredient that I buy in for this home-made, locally sourced, native porcelain body.

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After ball milling, I test the pH and adjust it if necessary, it usually needs to be reduced a little, as the ball milling breaks down the structure of some of the felspars and micas in the stone. This releases tiny amounts of alkali into solution in the slip. The effect of this is to constrain the plasticity of the porcelain and inhibit the ageing plasticisation. Once adjusted to the correct level, the slip is stirred and then put through a fine sieve to remove any oversized particles and any foreign matter that has crept in during unloading. Thick slip is very slow to pass through a very fine mesh, so I resort to using a sieve vibrating machine to shake the sieve while the slip pours through. It’s quite amazing just how fast this process becomes with a little vibrational energy to keep the larger particles moving and not sitting and blocking up the fine mesh. ‘Vibro energy’ a really great focussed use for very small amount of electrical power.

Without the rock crushers and ball mills, I couldn’t make this local ‘native’ porcelain. In the past I always used to feel a bit guilty about using electrically powered machinery, as I was brought up in a family where ‘green issues’ were openly discussed, long before the ‘greens’ were invented as a political movement and ‘green’ came into the environmental lexicon. I’m not too sure what my parents actually called their lifestyle back then. Possibly ‘environmentally conscious’? Anyway, I’m happy to be called a ‘Greeny’ now and all that early environmental awareness has stuck with me. Give me the boy till he is 7! Now I am getting used to thinking differently about electricity as we are slowly becoming a fully electrified solar-powered household.

Electricity was always made with coal here in Australia and most of it still is. You have to specifically request to be put on a green power contract, and then pay a premium tariff for the pleasure of not using coal. 25 years ago, you couldn’t buy green power. Everything was coal, coal, coal, so I decided to make an effort to use the absolute minimal amount of electricity and we were very successful. We learnt to run a very lean electrical household. We have a very modest ‘LED’ screen television. A very efficient fridge that runs on 1 kW per day and a front loader washing machine, also very efficient. All in all we average an electricity usage of around 3.5 kWh per day. Very modest. We have chosen not to buy home theatre,  a dish washer or air con.  We have had solar hot water for the past 30 years, Solar electricity for the past decade and a Tesla battery since the start of the year. To the best of my knowledge, we have completely removed ourselves from the coal economy now.

When we did buy power from the utility, up until last year, it was always a battle to buy ‘clean’ green energy. They just hadn’t thought about it and weren’t prepared for the transition. It was a dinosaur industry. People like us wanted to buy clean energy, but they hadn’t put any plans in place to create any. It was all about business as usual. As the requests grew louder, some clean energy was slowly introduced, such that you could buy just 10% of your electricity as so-called ‘green power’, but it turned out that it was only hydro power from the Snowy Mountains Scheme. This was electricity that was always being generated since the 50’s and sold into the grid as part of the usual mix. But then the bean counters and ‘The Men in Suits’ got involved and thought why don’t we sell Steve Harrison the electricity that he is already buying, but sell it to him at twice the price. If he is silly enough to pay for it!  I wasn’t, so I didn’t.

We waited a long time, until the first wind farm was built just South of here. Then there was an offer that you could buy 20% of your power bill as wind energy, so we did, and continued to increase the percentage every year or so as more clean energy was built and made available. I remember that we were early adopters and had to go on a waiting list to get a higher percentage of clean energy. However, the energy company kept sending us supposedly attractive offers to change back to a cheaper dirty black power contract. This just reinforced to me that the market for green power was stronger than that for coal power. Apparently they had too much coal power and couldn’t get rid of it all.

Then there was government intervention to support the coal industry and then privatisation that was supposed to make every thing more efficient and cheaper. And what happened? The price went up about 200% here. A complete failure of market forces and competition.

Today I check in on our power usage on my phone app. I see that we are making about 5kW of solar power, not too bad, seeing that we are just a month off the winter solstice. We are only using a few hundred watts intermittently, that’s the fridge compressor switching on and off. There is a spike at 8am. That’s the toaster and electric jug for breakfast. It’s probably hard to live any kind of normal life and use significantly less power then this on a regular basis.

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Back to my clay tests and I pour them out onto the drying bed to stiffen up. Again I’m using solar and wind energy in this very passive way now to remove the excess water from the slip and reduce it to a plastic state. The sun shines for free every day. The wind blows most days, slowly the water is evaporated from the slip and it becomes stiffer and plastic. It’s gentle, it’s energy neutral and it’s free!

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Nice.

I’m very lucky to be able to live this rewarding, creative life in carbon constrained times. We are preparing ourselves for a creative, energy passive future, but it’s funny that trying to live a simple life gets quite complicated at times.

Firing on Sunshine

We have had our new Tesla battery for a couple of weeks now and we have just done our first electric kiln firing on sunshine.

We have had 3 kW of solar PV panels on our kiln shed roof for over a decade now, but we have only recently managed to get our hands on a new PowerWall 2 lithium battery, after being on the Tesla waiting list for over a year. The battery is working perfectly, just as we imagined, and now allows us to run our house and pottery almost totally independent off the grid. We had decided to stay connected to the grid however, as we generate far more solar electricity than we use ourselves most of the time, and up until recently we got a very handsome rebate payment for the power that we sold.

Now that the generous rebate program has ended, it is much better for us to store our daytime solar electricity excess and use it ourselves at night, instead of paying the premium cost of buying back ‘green’ power from the grid at night.

Of course we don’t have to buy ‘green’ power. We just choose to, because we made a decision 13 years ago to remove ourselves from the coal economy. Which we have done. We are of the belief that global warming is real and that it is man-made. Burning coal to make electricity is a very big part of the problem, and green power is going to be part of the solution. It’s affordable, it’s here now and it’s the future. In addition to going solar, we have also declined to use concrete slabs in our building construction and we choose to drive the smallest fuel-efficient car that we could afford.

When we put the first Australian made solar panels on our roof 11 years ago, we didn’t do it to make money. We did it for ethical reasons. However, as it turns out, we paid off the panels and made a slight profit over the decade, because we were paid one or two thousand dollars a year for the power we sold to the grid, but we also didn’t have an electricity bill for that decade. A saving of many more thousands of dollars. These original PV panels still have another 15 years of full productive life in them, before their output starts to decline. I’ll be long dead before they stop working. We recently added another 3kW of PV at the same time as the battery. As I intend to buy a fully electric car as soon as they become available at an affordable/reasonable price.

So now with everything in place, we have just completed our first electric kiln firing using our own solar power, firing through the day on sunshine up until just after lunchtime and then into the afternoon on a mix of solar and battery, then ending in the evening mostly on the battery power. Yes, it works. You can fire on sunlight. The future has arrived!

Below you can see a graphic of our power usage though the day.

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The high blue spikes are the electric kiln switching on and off. The golden-yellow hump in the middle, above the line is the solar panel output from the roof. The green areas below the line is the battery being charged up from the solar PV panels in the morning and corresponds perfectly with the yellow solar area above the line, up until noon. The solar panels are both firing the kiln and charging the battery up to noon.

After 12 noon, there was some cloud that came over and the solar output dropped down. By about 3 pm. the PV panels no longer generated sufficient power to both fire the kiln and charge the battery. After 3pm the clouds cleared and solar output increased again and fired the kiln with the assistance of the battery. From 4 pm onwards, the battery fired the kiln with assistance from the solar. Solar production ceased at about 6.30 and the firing finished at about this time also, more or less solely on battery power.

The small zigzag ripple on the base line is the household usage, mostly this comprises the fridge compressor switching on and off. I should also point out that I was also working in the kiln factory throughout the day and using some very heavy 3 phase sheet metal machinery, welders and plasma cutter. This is included in the blue spikes. The lower line of blue spike peaks is the kiln alone, and the higher level of blue spikes is the kiln and the heavy electrically powered machinery working at the same time.

The following day, the PV panels charged the battery back up to full power again by about 1.30pm. Solar output is shown in yellow. The battery shown in green is being charged below the line. Once the battery is fully charged, the solar output is then switched to sell back into the grid for the rest of the day. Shown in white below the line. Household usage is shown in Blue above the line. You can see that we run a very energy-efficient household. The blue spikes represent the toaster and jug in the morning, then the washing machine and then me using the heavy 3 phase welders, and sheet metal machines intermittently in the kiln factory through the day.

By way of explanation, I downloaded this screen shot at 3.30 pm, so that is why the graph suddenly stops.

 

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From this brief explanation I hope that I have illustrated that it is possible to live a ‘normal’ life, carry on working and fire an electric kiln, all from a solar array and a lithium battery.

Food for thought?

Some technical details;

The battery is a Tesla Powerwall 2 lithium-ion battery with a 15 kWh rating.

The solar array is 6 kW. Made up of 3kW of 11-year-old BP solar panels made in Sydney, and 3kW of new ‘Tindo’ solar panels made in Adelaide. In both cases, we paid a premium to purchase Australian made panels to support Australian industries and Australian jobs. If there had been a comparable Australian battery. I would have bought that instead.

The Tesla Powerwall 2 lithium-ion battery is 15 kW/h rating. Made in the USA. The closest Australian contender was ‘ZPower’  also from Adelaide, but at almost 3 time the cost, it was out of our price range. All these things will change quickly and dramatically over the next few years. Watch this space. You can be sure that whatever will replace our battery at the end of its life in 15 to 20 years time, hasn’t even been thought of yet, never mind being built!

The kiln is one that I made myself. It is a half metre cube 500mm. x 500mm. x 500mm.  constructed out of light weight RI bricks.

 

Kiln Number 300, gone to the galvanisers

My 300th kiln is all welded and has gone to the galvanisers. The workshop is now empty and ready for the next few weekend wood firing workshops. This last weekend we had our 7th workshop for this winter/spring season. Only 4 more to go and then its all over for this year. Janine and I are fully occupied collecting, cutting and splitting wood during the week to keep up the wood fuel supply. With 6 kilns going all day, we get through the work pretty quickly, as well as the wood.

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We glaze, pack and fire continuously all day. With each firing, our participants become more familiar with the glazes and the process. Today we have a majority of students who have not done a raku firing before and who have never fired a kiln by themselves before, not to mention that these are very hands-on wood fired kilns. It’s a steep learning curve, but we take it one step at a time and it all goes smoothly and some really beautiful work get made.

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These two pieces made by Jude Keogh from Orange. Photo by Janine

 

 

The Last Day of Winter

Here we are already at the last day of winter. The day starts with a witheringly cold morning. We wake to find ourselves cold even under the sheets in our bed. There is a very healthy frost laying all around. No point in trying to water the garden too early, as nothing will work out there.

I have had this last week ‘off’ to try and catch up on jobs that have needed attending to for some time. Everything got a bit neglected while I concentrated on getting my book printed and my big exhibition up at Watters Gallery. The show is in its final week now and will come down on Saturday. It’s a really good show, if I can say that about something that I have done myself. I’m pleased with it. It couldn’t have been completed or have been as successful without the total support of my partner Janine King, as well as all the help from all the people that I collaborated with over the 15 years of the research. Thankyou Janine!

On Monday, I will start to weld up my 300th kiln! I have one more big kiln booked in after that, with deposit paid, to be welded before the end of the year. I will then be 66 years old and it’s time to retire from building the bigger, heavy kilns. I will continue to make the smaller, lighter, monocoque stainless steel framed ‘dual-fuel’, wood fired and gas fired kilns for a while.

I went down to the steel yard to buy the required steel sections, so that I will be ready to start work on time next week, and while there noticed that they had a load of used pallets that needed to be taken away. As I had the truck and all the steel was up on the racks. I decided to fill the tray with pallets. These can be broken down into small, thin sections that are very good for firing the small ‘dual-fuel’ kilns in wood fired mode. After I get all the steel off the carry racks, I take the truck to the kiln firing area and unload, then cut them all up with the chain saw, into shorter, straight, sections. These are then taken to the wood shed where they are split into thin pieces and loaded back onto the truck and stacked into the trailer standing at the edge of the raku firing space, ready for use in the next 4 low temp wood firing workshops. We have almost enough wood in stock now. It will need just one more day or two to collect enough to see us through to October and the end of the firing season.

 

During this last week ‘off’, I have also pruned the peaches, almonds and shiraz grape vines. All these jobs have needed doing for some months, but now is their time. I also need to be getting stuck into the cherry trees, but time is running out. In small moments each day at lunch time, I get up on the Old School House roof and fix the flashing, repair the fascia and paint, prime, and top coat a series of rusty patches where pine needles have collected over the years and caused the galvanising to corrode. I notice these rusty patches every time I get up on the tall extension ladder to clean the gutters. This job can’t wait another week, so I manage to fit it in.

 

 

One other job that has been waiting almost a year now, is the water tank on the chicken shed roof. I was given this galvanised water tank for free, because someone? Built it very badly and put the water inlet filter hole in the base, rather than the top. Useless! i managed to silicone and pop rivet a gal patch over the hole and make a new hole in the top where it belonged. All too easy, but when it filled up with water, my patch held well, but there were 3 other places where it sprang little spouts of water leaks. It’s been very dry , with no rain for several weeks now. So, I take the tank down off its stand and dry it out completely by cutting the entire top out, so that it can fully drain and get sufficient air movement to completely dry out. When it’s dry, I can crawl inside and brush it out and clean it well, then apply 4 tubes of silicone rubber to all the internal joints and seams. That should do it!

i use up a lot of small off-cuts of galvanised steel sheet to make a flange on top of the tank and replace the original lid, all pop-riveted back into its old place. No one will ever know!

The last job this week, which we have tackled each morning and evening, is to wheel barrow 5 tonnes of mushroom compost into the orchard and spread it around all the stone fruit trees. I started the week by mowing, then spreading wood ashes from the fire all around the drip line of the trees. I find that all the old marrow bones from the stock have been calcined in the fire and are now reduced to a soft crumbly, powdery state. I spread it all evenly around. The wood ashes will provide potassium, the calcined cow bones will provide phosphate, and the chicken manure that  I add will provide the nitrogen. Its a home made, balanced diet, of naturally produced fertiliser for the fruit trees. It just couldn’t be more natural and organic.

 

 

 

The chickens come and help to spread the ashes and compost and get a cuddle for their work efforts from Janine.

 

 

Low Temp Wood Firing Workshop

We have just completed our 4th wood firing workshop for the season. We still have 4 or 5 to go before spring, the hot weather and possible fire bans arrive.

 

We hosted 11 potters in our workshop for a low temperature ‘raku style’ firing day. We have re-arranged the order of the kilns for this event, placing all the small ‘Stefan Jakob’ style ‘IKEA’ Garbage can kilns up on the stone wall. In this way the potter doesn’t have to bend down to stoke the firebox, but instead, can sit in a more relaxed fashion in a chair while stoking the kiln. This is much easier for some of us of advancing years.

 

The larger and heavier brick lined portable kilns have to stay firmly on the ground where we can wheel then out for firing and then back again under cover for storage.

We were blessed with a beautiful day with no wind and beautiful sunshine – almost hot. Such a great day for an out door workshop. The week preceding had been dreadful with strong, icy southerly winds blowing off the snow.

Everyone seems to be happy and some excellent results are achieved. We are now about half way through our firing workshops for this year. 4 down and 6 to go.

 

My New Book – 5 Stones

IMG_7383205 pages, 125,000 words, full colour, soft cover. Written, collated, printed and bound on the kitchen table. A very limited edition hand made book.

I have spent the last few weeks and months editing and formatting my new book. This will be my 6th book and 7th if I include my contribution to Handbook for Australian Potters.

This new Book is titled 5 Stones, and details my recent research into single stone porcelain. The book will be launched by Grace Cochrane at the opening of my show at Watters Gallery on Wednesday 16th of August from 6 to 8 pm. I have a selection of single stone porcelain from all 11 sites on show in the exhibition.

15 years ago, I discovered a white porcelain stone near where I live. It made me think about where else porcelain has been discovered and when. Over the past 15 years, I have travelled to each of the places in the world where porcelain was originally discovered/invented independently from first principles and found that they all had something in common, and that thing was a stone called ‘sericite’. It turns out that originally, porcelain wasn’t made from the white clay at all. Kaolin wasn’t involved. All the original porcelains were made from a special type of stone called mica.
My travels led me to China, Korea, Japan, Cornwall, France and Germany. I even developed communications with academics in California, Alaska and London. Then finally back to Mittagong in Australia. Near to where I started.  I have made my porcelain pieces out of these weird and interesting materials in remote villages, artist studios, back rooms, workshops, even factories. Where-ever I could track down and find amenable people using this ancient technique who were open to collaboration. 
At each site that I visited I made works out of the local porcelain stone, but I also used the opportunity to collect samples of their stone and posted these rocks back to Australia where I could process them myself and make local, contemporary versions of these ancient porcelains. I collected native porcelain stone material from 11 sites around the world and have made what I think are beautiful pots from them, both on-site, where that was still possible and back at home in my own workshop. 
This exhibition shows results of my firings and 15 years of research into these single-stone native porcelains. To coincide with this show I have written a travel journal documenting my travels. My book, titled ‘5 Stones’ will be launched at the opening by Grace Cochrane. The book stands alone in its own right as a travellers tale, as it has its own characters and arc of narrative, but also helps to illuminate the story behind the actual works on display in the show.
I have works in the show that were fired on-site in clean conditions to give very white and translucent pieces and I also have the same materials fired at home in my wood fired kiln with very different results.
4 of the 11 examples are made from porcelain that is no longer available, as 2 of the sites are lost forever and another two have complications.
I consider my self very lucky to have been able to get my hands on all of these ancient and very special porcelain materials. This will be the first and only time that all these porcelain ‘clays’ have ever been shown together in the one place.
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Unglazed and flashed wood fired Arita porcelain
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Wood fired and celadon glazed Japanese porcelain, fired in my kiln in Balamoral.
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Korean porcelain made onsite in Korea
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Woodfired Japanese porcelain
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My woodfired local Joadja porcelain, showing some carbon inclusion on rim and base.
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Korean porcelain stone body, woodfired in my studio.
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Amakusa porcelain from Japan, made in Arita.
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My local Joadja Aplite porcelain, wood fired with a lot of ember and ash contact. The intense carbon inclusion reduces the translucency.
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My local Joadja Aplite porcelain, wood fired with ember and ash contact.