Kiln Building with Joe Finch

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DAY 1

I spent the weekend at the home of jeweller and ceramic artist Linda Unsworth (Pampeliska) in the Preselli hills where a group of us had got together under the leadership of potter and expert kiln builder Joe Finch to build Linda a small wood kiln in the garden.

We began with a flat concrete base into which holes had been drilled to let the moisture escape. It’s also possible to build onto a base of hollow concrete blocks with insluating blanket over the top. Firebricks had been laid out on top of the concrete in the shape of the kiln’s base and we built up onto this one layer at a time, photographing each layer. On the outer brick layer were light insulating bricks and heavier firebricks on the inside wall against where the flames will be. The chimney was built in a more aesthetic red reclaimed firebrick.

Joe’s kiln design is five bricks across and four wide and he’d built a model from Lego to guide us. Joe advises working out the size of the kiln you want after deciding how many kiln shelves you want to fit inside. The two chambers either side are fireboxes into which the wood will be fed through two openings at the front creating a ‘fast fire’ down draft style of kiln – the chamber in the middle will pull the flames back down and out the chimney. You can see in the photo that the second layer of bricks is pushed out slightly in the firebox to create a ledge. This is for the perforated brick layer to sit on. The idea is that the embers from the logs burning on the firebars above will drop down onto these and the oxygen through the holes will help combust them, meaning you don’t have to rake out the embers so often like in other kilns. In the chimney you can see a space where the bricks are missing – this is where the damper will be placed and bricks can be pulled out here to create reduction.

As the kiln got taller we added the firebars – hollow tubes of refractory fireclay onto which the logs will be placed. These need to be loose enough so they can be pulled out and replaced if needed. We continued to build up the bricks layer by layer, insulating on the outside and firebricks on the inside, sometimes having to saw bricks in half to fill in cracks and filling smaller gaps with gaskets of insulating ceramic fibre. Things became more complicated when we began the kiln chamber floor. We placed the flattest kiln shelves we could find on top of the fireboxes, leaving two gaps for the back for the flames to flow through and one at the front in the middle. We covered the flue to the chimney too.

Things picked up after this stage when the job got easier – we simply built the insulating bricks up in layers around the perimeter of the kiln chamber. Once the desired height was reached (about 2m high for the entire kiln) Linda painted numbers on the bricks that will make up the door using watered down red iron oxide. Joe then sawed out the door.

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DAY 2

We began Sunday morning by mixing up a mortar for the reclaimed molar bricks for the outside kiln cladding. This second layer of insulating bricks isn’t necessary but makes the kiln look more aesthetic. As a cheaper alternative it’s possible to cover the inner layer of bricks in insulating fibre then add a corrugated iron shell.

The mortar was a mixture of ball clay, sand, water and red iron oxide (the iron colours the mixture pink so it blends in better with the red bricks). The bricks were each soaked in water for a few seconds before building with so they absorbed the mortar better. Since the bricks were reclaimed we spent some time scraping the layer of old mortar off the surfaces before we could begin the next stage.

The cone spyholes in the back had to be adjusted for this second layer of bricks so we made new longer ones which can be pushed in at an angle. After completing one wall of outer layer we added the supporting angle irons on the outer corners and secured these together with a 12mm threaded rod (could use 5mm), then slid in horizontal ones between them.

The roof was constructed with three layers of insulating bricks cut at angles to make an arch. A D shaped wooden arc support frame was held up by planks underneath and we built the arches over the top, supported either side by bricks cut in half length-ways. Once the other outer walls have been completed the frame should be able to drop and slide out through the kiln entrance leaving a freestanding roof. Unfortunately by the end of the weekend we’d run out of the reclaimed bricks so we couldn’t complete the outer layer fully but Linda has promised to send photos of the finished kiln – I’m looking forward to see the results! More information about kiln building can be found in Joe’s book ‘Kiln Construction: A Brick by Brick Approach’.

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Anagama Day 3-5: The Firing

The past three days have been spent at HDK’s kiln site at Nääs where we fired both the anagama (Mamagama) and Elinor (the smaller wood kiln).

Since Elin and I were scheduled for the first shift on Monday morning, we arrived on site around 6am and started up the anagama. We pulled out the bricks from the central air hole at the base and built a small brick box in which we set fire to some newspaper and placed dry kindling on top. We began by taking the temperature up at a slow pace, 25C per hour until reaching 100C, with the fire still mainly in the box outside the kiln. As a temperature gauge we used a pyrometer stuck through a crack in the door but later decided to place it in a hole in the kiln’s roof to get a more accurate reading of the inside temperature. We sealed the door with the daub we made last week, blocking out the bumble bee who was desperate to get inside despite the rising heat!

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Starting the firing
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Firing temperature schedule

After four hours we let another pair take over and we worked this way in shifts of four hours per team for the entire firing. Around 10am Elinor was started and taken up to temperature at a much faster rate. Reduction in Elinor took place on Monday afternoon when the kiln had reached 1000C. Creating a reduction atmosphere before this temperature means the clay can get reduced instead of the glazes which can cause it to trap carbon and turn a very dark colour which might be undesirable.
Sometimes when too many logs were fed in too quickly, black smoke started spewing out the chimney – a sign reduction was taking place, and we had to be more patient. It’s difficult to get the balance between allowing in enough oxygen for the flames and allowing in too much which starts the reduction process because the cold air blocks the flow.

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Feeding mamagama

When feeding logs into the kilns the temperature would fluctuate up and down a lot, sometimes peaking three times before finally decreasing for good. We were told to focus on the fire and not rely on the pyrometer though. It’s possible to hear when the kiln is ‘hungry’ again because the fire goes quiet and the crackling stops. We also used pyrometric cones placed at the front, middle and back of the kilns to check temperature. When the cones were bending unevenly e.g. if on the left side there were four standing and on the right five, we put in less wood and slowed down the temperature gain. Another way to check if the glazes are melting is to poke a stick in through one of the anagama’s peep holes and see if the pot’s surface is shiny enough to reflect off it, a technique I’ve used before when firing raku.

It’s important to make sure that the last logs have turned into embers before more have been added. Unless you do this you find yourself in a situation like we did early on Wednesday morning when the anagama would refuse to climb above 1220C. Looking into the airholes we realised that the embers were so high that they were blocking the oxygen flow into the kiln so the fire couldn’t grow. By pulling out logs and moving around the embers inside we fixed the problem, but the temperature dropped dramatically so we worried that we would be behind schedule. This could be fixed though by filling the door with long thin sticks sticking into the flames which raised the temperature.

In between shifts we took turns breaking down the logs with a hydraulic wood splitter and cutting some down even smaller with an axe. Smaller pieces of wood raise the temperature because they burn quicker but it’s best to use a mixture of thick and thin, long and short logs to get an even rise. When stoking the kiln, sometimes we would place two small logs crossed in the doorway to conserve heat.

Our fifth and final shift started at 6pm on Wednesday night. We kept the temperature around 1250C until 7pm when we topped at 1300C before bringing it back down to 1270C. We topped another 5 or so times before filling the kiln with as many long sticks as possible and sealing as many holes as possible in turns. This was probably the most stressful part of the firing because it needs to be done fast and the kiln is at its hottest. It was impossible to feed in logs for very long because your legs feel like they’re burning! It was necessary to wear welding goggles, scarves over our hair and mouths, long sleeves to cover arms and legs, sturdy boots and flameproof gloves. After sealing the gaps in the kiln with daub, cold water was poured all around the kiln to make sure none of the logs piled around it would catch fire once we left.

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The kiln in the evening sun, glowing at 1300C

 

Masayoshi Oya

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Top half Japanese inspired, bottom half Swedish aesthetics

As part of our theory course today where Dominique and I discussed the different approaches to our disciplines in Sweden and the UK, we were visited by Gothenburg based Japanese ceramic artist Masayoshi Oya. He explained that since moving to study in the city years ago, his way of working is a fusion of the aesthetics of the two countries. Oya explained that in Japan functional tableware has a higher status than ‘art objects’, which is radically contrary to the west. Since the times of the samurai the society’s approach has been that the most beauty can be found in objects made for ordinary people.

He also described the difference in how both countries expect an object to be viewed over time. The Japanese concept of wabi sabi as he explained it means pots are glazed with a matte surface so that they pick up marks and scratches with use as they age. These imperfections make them more beautiful. On the other hand, in the west we want our ceramic to stay the same over time, to always look as brand new as the day we bought it.

His comments about time reminded me of the Chiharu Shiota exhibition at Goteborgs konstmuseum in which thousands of individual threads have been stuck together showing that an immense amount of time and effort went into making the installations. Similarly to the wabi sabi aesthetic, time has become tangible. By being able to visualise the time taken ( or the age in the case of wabi sabi) we have a greater respect for the art.

Oya explained that his black stain on porcelain signature decoration is inspired by calligraphy and specifically, calligraphy as approached by someone in the west who is more interested in the way the ink breaks at the edges than creating the lines of a Japanese master calligrapher. He spoke of the way swedes like to stack their tableware and have everything matching whereas in Japan it’s more common to have mismatching vessels to serve food it. Rosa recommended a book called ‘A feast for the eyes: the Japanese art of food arrangement’ which discusses further the relationship between Japanese food and utensils from the Jomon period to the present.

Artist website: http://www.masayoshi-oya.com/

 

Images: http://ceramicartistsnow.com/2018/02/04/studio-oyama-swedish-pottery/
http://www.masayoshi-oya.com/index.php?/works/hei-nippon/

Object for Ken Stradling

For the third year in a row, second year ceramics at CSAD have been invited to create an exhibition at Bristol’s Ken Stradling collection by responding to objects from the collection. Unfortunately I don’t have the chance to return to see the collection for myself, but I’ve scoured the website and found a piece of design which captures my imagination – Eric Magnussen’s stainless steel ‘Vacuum jug’ (designed 1976).

In order to paraphrase the jug I’ve been playing at word association – space, double walled vessel, temperature, asymmetry, interaction, thermal, insulation…

       INSULATED
Origin: From the Latin ‘insula’ meaning ‘island’, connotation of protection.

I’ve decided to work with the idea of insulating. As a starting point I intend to buy spray insulation foam to create some forms and then make plaster press moulds of these to use. I’m thinking about islands, the space in between, emptiness and transition. I’ve heard the term ‘liminal space’ bandied around, maybe it’s time I dug deeper.

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Vacuum jug in the Ken Stradling Collection

HAPTIC Exhibition, Arcade Cardiff

A selection of my work is currently on show at Three Doors Up, Queens Arcade in Cardiff as part of ‘HAPTIC’ – a tactile exhibition of ceramics sculpture curated by my very talented friend and flatmate Heledd Evans. Proud to have my sculpture featured on the poster! If you’re in Cardiff, drop round to see what the ceramics students at CSAD have been up to! The show runs until the 24th of March.

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4 Top Tips for Studying Abroad in Sweden

What’s happening in your second week living in Gothenburg do I hear you ask? Well, with care not to turn this into a make-up blog, since I haven’t seen sun in so long, I’ve noticed my foundation has suddenly become five shades too orange for my skin. I’m having to choose each morning whether I’d rather look like Tim Burton’s corpse bride (a less sexy version) or an oompa loompa for the day. So important top tip #1 for students going abroad to study in Sweden – leave that match perfection at home. Bring lots of moisturiser though, if you’re anything like me, the change of climate will dry out your skin like crazy.
Top tip #2: Beware day 11. I’m not sure if this is just from my experience or if there’s some scientific reason behind the maths, but yesterday seemed to be a struggle for a lot of people who moved here on Monday last week. It felt like the day we’d been the most tired so far at our new university. So my advice is – take it easy. There are likely to be loads of social events to go to in the first few weeks including pub crawls, buddy group get togethers, info fairs, welcome receptions and so forth, but don’t feel pressure to go to everything that’s organised.
But when you do go to parties and get togethers keep in mind top tip #3: Make an effort to remember faces. Names are difficult, especially since you will be meeting students from across the world, many with names you’ll be unfamiliar with and have trouble pronouncing. But the amount of times in the past few days I’ve asked someone “Who are you then?” and they reply “What, we were at the pub together last week!” and it dawns on me that we had a long conversation only now they’re not wearing glasses or they have a different pink hat on, is a bit embarrassing.
And finally Top tip #4 is basic: Remember to bring all your important Erasmus documents to be signed by the host university. In my excitement to move abroad I may have got distracted researching where to find the best charity shops and somewhere along the line misplaced my learning agreement. Don’t do this. You need to get it signed ASAP in order to receive your monthly allowance from Erasmus. Gothenburg is an expensive city to live in!