Talking sh*t

....specifically dinosaur dung....fossilised dinosaur dung. I get regular contact from people who are asking for advice and help developing their own glazes out of found materials, but this has to be the most unusual. I have been commissioned by a conceptual artist, based in The Netherlands to develop a glaze that is based on fossilised dinosaur dung - or coprolite as it is properly known.

This is a sample in cross section, showing the variations, seams and nodules in it. From reading up on it I believe that these represent the animals last few meals, remnants of these remaining in the fossil. Items found in dinosaur coprolites include fossilized bone, teeth, fur, plant stems, seeds, pollen, wood chips, fungus, insects, larvae, dung beetle burrows, fish scales, shells, and glassy marine organism microfossils 30 to 50 microns in size.

 This sample has been weighed and calcined to 1000C, reweighed and is then steeping in concentrated acid. I'm trying to get a better idea of what minerals are actually present in the fossil.

...and here are my first simple melt tests and lineblends - again designed to help me ascertain what potential glaze materials are actually present here. These results should tell me lot, including how hard or easy this project is likely to be. Fingers crossed.

Autumn with a vengeance

Where have the last weeks gone? The last thing I remember is enjoying our long late summer and the wonderful expansive East Anglian September skies, then the clocks went back and now dusk is beginning in the afternoon. It rained heavily all day today and the water butts are full.

As I write this the dark is rising and my feet are icy. It could be somewhat depressing but I find I have a workshop full of pots that are trying to dry and I am well on the way to having my first kiln load. My aim is to make enough pots for two firings in the large kiln, back to back, so that I have a good selection for Ceramic Art London and an exhibition I have in France next year.

 These are made with a couple of different very coarse clays, for the front of the kiln. They will be partially glazed at most. I have one more batch of grog to fire (all prepared and seived and in the gas kiln) for my final large pieces. The largest, at the front, is about 60cm long.

I've also been making a variety of new forms and building up textured layers od slips, from some of the many interesting clays that I have collected. these are for further back in the kiln, where they will be more protected.

I'm making the platters at the moment and then after that the final clay body - a kaolin based almost-porcelain. I'm currently ball milling quartz to go into it (nice and fine - around 120 -200 mesh), then next week it's the other igneous rock additions.
It's a slow slow process, so I'm hoping to fire early next year.

A lack of oxygen

I have collected a huge range of clays from various places that just won't stand stoneware temperatures. Some of these will only take an earthenware firing and others can be nudged up to midfire temperatures as long as the firing isn't too long. I've been trying to decide what to make with these and how exactly to fire them and finally made a decision over the summer.

I used clays from Leicester, North Devon and a river clay from mid- Devon, often mixed with quartz or crushed rock from the area they came from or homemade grog (!) from the same clay, to try and control the high shrinkages. I fired to cone 9, which in my experience is the equivalent of around cone 7 in a non-wood firing. A previous firing to this temp gave a uniform leather brown on everything that came out of the kiln, so this time I decided to change the habit of a lifetime and do a reduced cool. The small kiln drops temp. pretty quickly once the firing is over, so as it dropped to 1000C in about 2 hours, I stoked small pieces of wood and bark in through the sidestoke port fairly regularly, to maintain a nice soft reduction flame throughout the stack and just a small amount of smoke seeping through cracks in the top of the kiln.
Apart from a collapse it was an excellent firing and I began to see what reduction cooling can actually do. There was some wonderful colour variation, black carbon trapping, haloing around wads but most impressively a gorgeous lustrousness to many of the clays. Definitely a starting point for more experimentation.

A quick one before he's away

Back from Australia and I was full of ideas of what I wanted to do next. Not in terms of long heavily reduced firings, but developing where I am going with the forms that I am making and doing a short stoneware firing, packing the kiln  more in relation to temperature variation and seeing what I could achieve. Within a few weeks I had enough pieces made from a variety of bodies I mixed up, some of which are difficult to work with and very prone to cracking.

This being a good example - a body based on Dartmoor kaolin that is lacking in plasticity and has a very high fired shrinkage.
The firing started at 7am and went on till 2.30am (19.5 hours). being a small kiln the transition from firing from the front to inside the firebox is rather tricky and stressful, however after that it was the smoothest firing I have done in the small kiln. This was certainly helped by the stack of cut to length branches that enabled me to fire it like a true Bourry Box.

There is a relatively large temperature gradient within the smallish chamber, but careful packing resulted in a much much better firing, with good pieces throughout the pack.

This was right up the front, partly buried in the ash + has some stunning colour variations on it.

This was further back and fired on its side, but still has dramatic ash interaction with the Malvern Hills rock glaze.

.....the great unpacking....

...and here, as requested, in the last post from the Edge Of The Shelf conference, are some images of the work that came out of the kiln.

Here are Kirk Winter (left) and Daniel Lafferty (the organiser) inspecting unpacked pots.

Masaho Ono with one of the multi-form communal firing 'sculptures' from the collapsed front stack.

Chester Nealie got some of the best pieces out of the firing. This was the large jar up the front.

Mahito Kudo proudly displaying a Robert Barron jug..

 

...and finally, a piece by Michael O'Donnell, from New Zealand.

.....the firing as performance

....so, the kiln was ready and the pots, dry and wet alike, were taken over for the big pack. The back section was packed through the 2 side doors and the rest through the front. I did say wet, and I mean it. A couple of the bigger pots got knocked on the way in and were carefully molded and repaired once in place.

This image shows the back section, just behind the side arches, under the hump of the 'whale' kiln. In front of this stack went 3 large jars, then 2 more stacks before the firebox. Packing took 2 days.

This image is the view from the front stoke hole - Scott Parady's large jar resting on Ray cavill's prawn bowl (for people who really like prawns!). 2am the kiln was lit with a very gentle flame, curling into the chamber through the grate holes. This was maintained for the next day and night to try and dry everything out. The kiln was steaming, but hard to tell what was pot water and what from the cow dung.
The firing schedule was very different from mine - a slow rise in lightish reduction/neutral atmosphere till cone 8's were going. At this stage it became apparent that something bad was happening with the floor or props as the front stack began to teeter and lean forwards. Cone 8's went at the front sidestoke and sidestoking began, bringing the temperature up slowly throughout the kiln.
After around 24 hours at stoneware temps the front stack collapsed into itself and the stoking space behind it. Emergency caesarian was carried out to free up the stoking space, pots being removed with raku tongs. Some of these were rather good with a surprising build up of ash on their surfaces......ash and....salt! Yep, looked like a salt firing. It seemed that perhaps the wood that had grown at the site, being next to the sea and a large saltwater lake, had high sodium levels.

Day 5 was spent overstoking and building up large ember beds in all areas of the kiln - constant heavy reduction. Finally, spectacularly, sacks of charcoal were funneled into the whale's hump and back of the kiln. The temp in the kiln had dropped somewhat by now but the temp at the bottom of the chimney was crackling white - maybe cone 14 - 15.
3 days and some early brick removal later and the kiln was opened.

Amazingly, for a performance piece, with untested clays and slips, glazes, wood and kiln, there were some rather beautiful pieces in the firing. Even a few survivors from the collapsed front stack. Further back it became an almost unrelenting expression of grey, but even here the sidestoke areas yielded some interesting results. Did it make me want to explore reduced cooling? No....but there were some packing and firing techniques that I'm sure will find a way into my firings in the future.

Making with the unknown

I rarely post photos of me.....but here goes.
The first week we each grabbed a wheel and a table and got to grips with the range of clays that were stacked up at the end of the marquee. With little to guide us but colour and texture we set about preparing blends and mixes with the fat sand (that was being used as mortar for the kiln) and the white quartz filled kaolin from a nearby brick pit.

Pretty soon the racks were filling up with an exciting variety of work. Liner glazes and slips were mixed up by volume (with fingers tightly crossed). Within four days or so the kiln was finished, the packing and firing dates set and the race was on to dry everything out as much as we could. The atmosphere was buzzing - it was so different from my usual solitary making process - no competition, just pure enthusiasm.

To break the routine we got taken out on a variety of excursions, overtaking the local pub, fish and chips in Beramgui and an unforgettable climb up a nearby granite hill, with an aboriginal guide to a sacred site.

The hill stands high over the surrounding countryside and formed the backdrop to many of the places we visited, such as Daniel Lafferty's home and Tilba beach, where we went fishing and I (honestly) caught a shark.

 The sacred aboriginal site at the top of this hill was truly awe inspiring, with stunning, softly weathered, beautifully surfaced granite sculptural forms rising into the forest. Each had it's own story, as part of the dreaming for that place and within creation. Nature always does it best!

Back Up from Down Under

Aaaaah......jet lag. It's been a long time since I experienced falling asleep standing up. I flew in yesterday from a truly unique experience at the Edge of the Shelf Woodfire Conference in Mystery Bay Australia. The location was stunning - on the edge of a saltwater lake, right next to the ocean.

Those clouds soon disappeared and we had 3 weeks of glorious blue skies. Unfortunately for my blog, the internet access was extremely limited so I wasn't able to post live. Instead I will put up a series of posts that illustrate the event.

There were 21 demonstrators from around the world - France, Korea, Australia, New Zealand, Japan, US, Brazil, Nigeria and the UK, invited by Aussie woodfirer Daniel Lafferty and his team. The venue was originally built as a yoga retreat, with a central venue, individual yurts and cabins on acres of beautiful coastal land, that is now often used as a wedding venue. Luxury!

A number of marquees and tents had been erected, one being our 'studio', with racks, tables, wheels and pallets of clay. The first week was taken up with demonstrations, everyone working hard to make enough work to fill the kiln that was being built at the same time. Fueled by great food, excitement and Coopers Pale Ale, the making sessions went well into the small hours - it was almost like being at college again. Seeing the variety of making styles and work produced from the same materials was inspirational.

The arch of the kiln was finished by about day 4, then it was covered by a fireclay, sand and cow dung mortar. I counted myself lucky not to have to mix and apply this but it was impossible to escape the smell of it cooking as the kiln warmed up during the firing.
Most of the clays supplied were commercial but there was an interesting local clay brought in by Daniel, and I made up a glaze from pumice that I collected on the nearby beach.
More to follow soon........

Beauty and loss

It's been a tense few days. Despite the glaze peeling off some pieces during the firing (again!) it really was an excellent firing, with some truly stunning pieces. Some loud and brash and some quiet.

The glazes are on quite thickly and I am using all unprocessed, self collected materials so it shouldn't be too much of a surprise to get a selection of faults, but it is heart breaking to hear and see beautiful pots crack apart. There were no pots this time that failed in the firing and met the hammer on the way out but a few have since bitten the dust as they acclimatise to the outside world.
Hopefully the rest will continue to survive.

Now more relaxed I can enjoy the positives, but I have to think about the negatives to plan the next firing. I've never had dunting before and also a weird fault where the glaze seems to craze not only down to the clay but within itself, so that ash crystals on the surface feel rough and lift off in a little shard of glaze. Very sad that this has happened on an otherwise gorgeous piece.
Some new glazes include plenty from the Malverns. This is a dark semi matt glaze based on the Precambrian diorite and Triassic sandstone there.

Stoked, soaked, clammed and toasted

March and the beginning of April seem to have vanished in a puff of busyness in preparation for me trip to the On The Edge Of The Shelf woodfire conference in Australia. The last major event on my 'to do' list was another firing in preparation for my return.

The kiln was lit early Tuesday morning - nice gentle rise to 1000C by 3pm, then reducing to cone 8's down by about 8pm. Overnight it is held at this temperature - all pots are becoming shiny and sticky and receptive to the ash in the flames. Cones 9 and 10 slowly drop and the challenge is to resist the kilns desire to rise in temperature. It didn't thank us for this and 8am next morning sees it full of embers and sluggish. A change of settings and the embers are burnt away and time is spent getting some decent heat in the firebox, signaled by a lovely crackle from the wood as it is stoked. A combination of front and sidestoking and cone 12's are going over throughout. I raked the embers away from the front floor level pots then soaked for an hour or two till at 3pm the kiln was slowly bricked up, clammed up to seal the gaps and left to cool slowly.

Thanks to Andy for his great help in firing, cooking bacon and toasting the firing!

Building upper body strength

As the rain seemed to have stopped for a while I made the most of being able to work outside preparing wood (splitting by hand as my wood splitter has frustratingly burnt out its electrics) and rocks for my next batches of glazes.
The kiln was lit for a slow bisque. Muscles tensed, I approached the steel mortar and pestle with buckets of calcined rock.

I break up the rocks into manageable sizes with a hammer before calcining them in my gas test kiln. Then, using this mortar and a 1 1/2 inch diameter steel pestle, I crush them down to 8 mesh (around 2.5mm max diameter).
Calcining works best on igneous rocks with large crystals like Dartmoor granite. Unfortunately for my arms I had fine rocks such as Arthurs Seat basalt from Edinburgh.....

.... a triassic sandstone from Martley in Worcestershire, Pentland felsite and a metamorphosed granite from the Malverns that has separated into  thick swirls of quartz, feldspar and mica.
This  collection of buckets took me 4 hours and is now ready for the ball mill.

3 hours of milling and the grit is reduced to a fine dust that will readily pass through a 60 mesh seive, with about 90% through 100 mesh. I used to mill finer but find that  this slightly coarser grade gives good results.
The red lidded jar is 2/3 full of hard alumina balls, which tumble as they rotate, crushing the rock. I am milling most of the rocks dry....

...though I mill quartz wet for the best results, and to keep the dust down as I need this very fine. Here it is settling out (which takes about 24 hours) before it can be slopped onto a plaster batt to dry.










 For some reason I am unable to reply to comments on my post so......
Hi William. Don't mind at all. You can certainly use it to make a glaze. Try using it to replace the feldpar in one of your usual glazes or do a lineblend adding whiting and some clay. Good luck!

Hope I screwed the corrugated iron down well......

....the kiln is lit for another very slow bisque firing and the shelter I have built around it is rattling in these violent winds. I'm relieved  slightly by my choice in extra long hex head screws when I built it + by the fact that all the burners have flame failure devices on them.                                                                      

The last of the clays that I have made up have been used. This image shows a kaolin and ground quartz body from Dartmoor materials. It is the largest piece I have made from this body, being 38cm tall, but had to be made in 5 sections as the clay is so difficult to use.

Now all that is left is to make the setters and lots of testing.

The first set of tests, pictured here, are more lineblends of Malvern rocks. I'm still trying to get a good glaze out of the Precambrian diorite, which seems to me to be closer to a dolorite in its lack of silica. I'm blending a Triassic sandstone into the glazes to try and get a good melt.
Other tests include lineblends of materials from the Gog Magogs near where I live. The rocks and silts are glacial deposits + I am trying to get a beautiful glaze out of them for a commission. So far it is proving elusive, but if there's one thing a potter needs it's optimism!

Heading to the dark side

Drill out! Whizzing up buckets of slaked crushed secondary kaolin and covering myself with it as well. It turns to slip pretty well after I fish out the larger stones. Then it all goes through at 60 mesh slip to remove the bits of limestone that are unfortunately part of the grit that's in it.
Then plenty of its own grog added, plus grit (mostly quartz with some mica chunks) from degraded granite, stiffened up on plaster batts and, after extensive kneading, it is ready for action.

I've been making a few different forms from it, including some larger composite pieces. It's not that plastic but OK to throw as long as I don't attempt anything over around 30cm.






Most of the pieces that I am making at the moment are starting from fairly simple forms like these.....

....and getting altered and cut once they have stiffened up.

You can see the iron in the body and fired in the wood kiln it tends to come out a dark burnt chocolatey colour with orange flecks where more protected. It is a great contrast to pale glazes as can be seen in this piece. It is also very good with a fluid type of Dartmoor granite glaze, where the iron bleeds out of the body into the glaze with quite spectacular results.