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Making Pots

Loading Pots

Firing Kiln

Unloading Pots

Report

Making Pots -

May- July 2018

Steve's production line ready for glazing

This is a video from YouTube, taken during the Upwey Potters' Dorset Art Weeks exhibition - showing Laurence Eastwood making pots.

There are no other images of pots being made!

Loading Pots

Back section of the kiln, almost full.

Lottie's rhubarb forcing pot. Made using slabs wrapped around inside plant pots, the joins are spigotted.

She gets the prize for the tallest pot ever fired in the kiln (so far!).

Back section fully loaded, except for Steve's small "gorilla planted" offerings placed to fill the gaps.

Lottie's pot has been hidden behind half shelves, the top two pots are Laurence Eastwood's.

This is how the kiln was left the week before, now ready for the last day of loading.

Almost finished loading!

Juggling the last few pots and making space for the few larger pieces.

A close up of the top of the kiln, waiting for the last few pots at the front.

Fronde's sculpture happily in place!

Almost finished!

Just a couple more to be squeezed in at the top!

Done and dusted!

Ready to bricked up.

A slightly more haphazard alignment of vertical props holding up the shelves. Trying to use the thicker shelves, which are larger than the standard size ones, so a two shelves and a half are used across the width. The middle becomes out of alignment sometimes, but we try to keep the major weight going straight down through a vertical column.

All loaded and bricked up and the ceramic fibre insulation hung in place.

Waiting to see what the weather will bring. After the long hot summer, we have got it done before the forecasted bad weather on Thursday, hoping the firing on Saturday will be in good weather.....

Firing Kiln - Saturday 18th August 2018

Morning has broken!

Early morning view, breakfast time!

Bill had been preheating the kiln overnight since 8pm - drying out the structure and pottery slowly. A log in each firebox every hour! After 3am a couple of timbers as well to start the climb.

Sleeping in the car between stoking.

Bill did mention that from 5am he stayed awake and started to stoke the kiln with quicker burning timber.

Early morning flames.

Buildrite's 2"x2" shafts burned well and raised the temperature fairly quickly.

483C (plus calibration error of digital thermometer, real temperature nearer 520C)

Hotest ever acheived by 6.20am.

Did we mention Bill started the proper stoking at 5am?!

The spy-hole at mid morning, colour from the incoming flames and background glow.

Camera didn't cope with the focus, but quite a nice abstract image!

Nikki stoking, demonstrating one of the many postures used during the firing.

Sharon's fashion statement - the baggy, lived in look, accessories by Bungie-Strap Inc.

Martin and Steve attempting to increase the karma of the occassion.

Steve, after drumming for what seemed like several hours, entering a trance state, calling up the kiln gods to help make the firing go well?

Birgit with one of her new friends.

The firing crew.

Stoking at abiout 5.30pm.

Now using mainly pallet wood pieces. The thinner slats offer a larger surface area, so burn away quicker and leave smaller sized embers.

Tea break!

Trainee tea boy and stoker, Mark, urning the right to be allowed to fire something next time!

Spyhole flames.

During periods of overstoking, the expanding gases push out of the gaps in the kiln walls and gush forth when the spyhole brick is removed for inspection.

There was no large period of stalled temperature rise, normally experienced about 1100C. So the temperature climbed to almost 1200C reading (=1250C real) - but then stuck for a while, just short of the glaze melting point.

Part of the reason for the stalling temperature, was the introduction of a "musical" interlude.

This also gave Hugh, the H&S inspector, something to do and Paul, a trainee kiln pyromaniac, a taste of the true talents of the potters.

Bill's mastery of the hammer on saw instrument was not sufficient to allow him a solo spot.

The chanting may have helped keep the kiln gods away!

The pyrometric cones basking in the glow of the warming kiln chamber. Not quite ready to slump over yet.

The stoking crew discussing the next strategy to use to overcome the stalling temperature rise.

The result was allowing Steve to go home, when the temperature surged to 1220C (1270C real).

8.20pm. Slightly overstoked firebox!

The pizza oven can be seen on the left. The rebuild was faulty, as flames could get into it from the fire box, filling it with soot! Just as well, as the usual catering division was unable to attend in the evening, so Bill's long suffering wife, Diane, offered to oversee the production. She is unlikely to want to come back for that task after the resounding failure to be able to produce anything that looked edible - although for those with strong teeth the taste was not too bad!

9pm and the cones have started to bend.

The various stoking strategies all seemed to work or fail in equal proportions! It did seem that by this point the kiln was happy to feed on larger pieces of timber again, without stalling. The smaller pieces may fail to provide enough stored energy.

This image shows the positive pressure in the chamber escaping through the opened spyhole. The top joint between the door bricks and the kiln arch also leaked a bit, the ceramic fibre stuffing had failed to block some of the gaps properly.

The 1241C (1290C real) reading was the highest reached, briefly. Indeed the worry started about overheating, but then it fell back to around 1220C (1270C real).

At the end of a soaking for an hour or so, the stoking was stopped and the kiln crash cooled to about 1100C. Then it was clamped up and the chimney disengaged, by sliding the kiln shelf across the base and removing the passive damper bricks which allowed air into the chimney to stop it pulling air from the kiln chamber.

Unloading Pots - 20th August 2018

Monday morning - cooled down to 100C. Ready to open and reveal all!

The first peek!

Looking great, nice reduction, some ash toasting, only a few pieces fallen over!

Fronde's sculpture is alive and well.

Front after unbricking and Steve robbing a few of his pieces, in his excitement.

Note to self - try and get props more aligned and vertically upright!

Looking very good all over - cones well bent, even near the bottom of the chamber.

Back section of the chamber revealed, after the front section had been removed.

Another batch of great looking pots, especially Birgit's white with wax resisted carved lines (and a few copy-cats!).

Lottie's rhubarb forcing pot. Splendid result - it held together and got a good reduction and ash toasting.

Karen's birds bathing.

Laurence's vases, made while demonstrating - decorated with large rope rolled down the sides and then expanded out by throwing only from the inside. Lovely texture!

Laurence's pots, the two jugs, looking very impressive.

Sarah's pots packed ready to go.

Sarah's teapot.

Caroline's sculptures.

Some are made of black clay, all are decorated with found clays and wood stove ash, plus some feldspars and clays.

Nikki's plant pot and jug.

The jug decoration was scratched in while turning, later glazed all over and then the scratched marks were gone over with a pointed stick to remove the glaze.

Bill made Martin some bowls with three legs, which he decorated. They are for an unspeakable ritual use.

Close up of side of bowls.

Bill's pots being inspected by a hen.

Bill's unglazed urns all suffered from bloating - the clay bubbled in places. Maybe because they were fired without biscuiting, with tight fitting lids. So not all the carbon could get out during the early stage of firing and then burst it's way out later on.

Still functional for dry food storage (offers accepted), but not fit for human cremations?!

Bill wide bowl. You don't need to know that it started life on the wheel as an urn, but things got a bit wide - so it escaped the bloating syndrome and turned out right.

The iron-rich glaze was painted on in horizontal brush strokes, the various thicknesses of the same glaze give different colours.

Bill made this at his class, showing (off) how to make a thin base and wide rim.

The glaze is Cornish Stone and Whiting, with copper oxide. The copper reduces from normal green to pink and red.

Ditto on a smaller scale with less reduction.

One of Bill's large bowls. Decorated by Jennie and team with horizontal brush strokes, using dark brown glaze (as featured on beakers), copper glaze (as above) and shiny white on rim, which has picked up loads of ash speckle.

Nice one Bill!

One of Bill's smaller mortarium bowls.

More of Bill's mortaria, after the bases have been ground smooth and then washed.

One of Bill's larger mortaria.

Bill's beakers, from the top!

Bill's beakers, drying upside down.

Report and Conclusions

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This the graph showing the temperatures according to the digital reading over the time of the firing. This firing is the darkest squares. It was the quickest firing ever - in 26 hours from start of preheat to end of crash cooling period. Thus it is the steepest curve, with fewer flat stalling sections.

The fuel was very dry. Did we mention Bill stayed awake after 5am -raising the temperature more quickly from an earlier start. Steve behaved well in terms of getting the firing stoking pattern sorted out - shame his other behaviours were less impressive!

We have to ask ourselves if the attempts at increasing our Karma were part of the improved kiln performance?! Certainly Martin's singing bowl was well received. The drumming and chanting were maybe less spiritually uplifting, but did cause a smile to spread across the camp!

The pottery that came out was all very fine. The reduction level was about right - with good dark toasted sections and no areas too light. The ash levels were good, perhaps sparse in places away from the main flame routes. No pots required refiring to finish maturing the glazes.

Lottie produced Pot of the Month, but her father would say that, wouldn't he!

Shame about the bloated urns......

Comments are very welcome - email Bill Crumbleholme

Thanks to :-

The loading and firing crew. What a team!

Thanks for all the help, saving Bill too much effort, which might have worn him out - especially as he stayed awake from 5am on the firing day!!

All the folk who brought in their pots, foodstuffs and their company.

Buildrite for the pallets and other timber.

Simon for the loan of the lorry to move fuel.