Making Pots - Late 2016 & Early 2017

Bill's class made a few pots while blindfolded, as a Xmas Party Trick!

This is Steve making "Pot of the Night!"

Mark V-P and Bill made some bronze casting lost wax moulds with extra large sprues, which were filled with scrap bronze pieces. These were placed in the kiln with the aim of the bronze melting during the firing and running down into the void where the wax had been melted out.

Loading Pots April 2017

The back section of the kiln chamber loaded.

Bill subsequently discovered that he had stupidly loaded some of Jennie's pots that had Raku glaze on them! So they had to be removed and replaced with other pots.

Unfortunately the wide bowl at the top left did not make back into the kiln this time and then Steve pushed a box into it and crushed the rim. That followed Steve's similar distruction of one of Sam's tall vases. "You just can't get the staff!" Steve's certificate for kiln loading training may have to be revised!

Close up back of kiln loaded.

Closer up of back lower section loaded.

Bill & Birgit loading, selecting the next pots to enter the chamber.

Bill demanding one shaped like that!

Bill with his measuring stick - trying to find the last few pieces to fill the gaps.

The front loaded.

The furry looking things at the bottom front are Mark's bronze casting moulds.

Birgit, happy the job is almost over.

Just the bricks to build up the door.

Firing Kiln - 20th April 2017

7am after a night of pre-heating using fairly large, slow burning logs. Keeping below 200C until about 3am, to allow all the water in the pots, shelves, kiln bricks and insulation to dry out slowly. Much of the pottery had not been biscuit fired, but glazed "raw" - or not glazed at all.

Temperatures crept up to 300C at top of chamber and 240C at bottom by dawn. So nicely dried out and ready to burn!

Master potter Bill's early morning consultation with the works of Confucius.

A young visitor also reading, but maybe not so intent on the pottery side of things.

But brother was happy watching all the action.

6.30pm The digital thermometer had reached 1190, after the afternoon's slowly increasing stoking rate.

However the cheap digital thermometer is out of calibration by up to 50C, so the glazes were melting by now.

Steve's supper toasting away.

The digital readings stayed stuck between 1190C and down to 1170C for the most of the rest of the firing.

Apparently this is an homage to a famous movie moment, but perhaps the axe should be in the shot?!

Sam arrived a bit late, so was set to work breaking pallets, allowed to use Martin's new device, which works really well.

The firing saw a lot of flames coming out of the top of the kiln chamber, whenever new wood was introduced. It was also a smokier firing than usual. There was very little breeze and chimney was feeling lazy!

This is at about 10pm.

Various stoking regimes were tested. Meanwhile the glazes were enjoying a nice soak to get matured.

Richard stoking at about 10pm.

Richard still stoking

The removable "passive damper" bricks at the base of the chimney were taken out to check out the flames coming into the chimney and to see if cutting the pull of chimney did anything for the temperature level - an increase following by a decrease, possibly nothing to do with the bricks!

This shows the tunnel from the kiln into the chimney. The sliding kiln shelf is kept fully open until the very end of the firing, when it is slid in to stop the kiln cooling too quickly.

The brightness of the flames entering the chimney gives an indication of the nature of combustion in the chamber.

A good plan is to let the flames dim down a little before restoking, otherwise too much unburnt gas is going up the chimney and thus wasting energy.

However the amount of embers in the fireboxes also needs to be kept at a reasonable level to provide the immediate heat needed to combust newly introduced fuel, that event lowers the temperature, until the new wood starts to burn properly and release more energy.

This was about 11pm.

Trainee Stoker Deborah in action, at about 11pm.

The timber fuel for this firing was mainly pallet wood, in very dry condition.

Some of it was split lengthways to increase the surface area and promote quicker burning, that also gave Richard something to do with his axe!

There were also some old church roof battens left from previous firings.

The stokers staring at the temperature reading, willing it to increase! Therein lies madness!

11.20pm

The spyhole brick removed to check the cones, which were bending enough to show a good temperature had been reached - about 1260C

Although the reading only just reached 1200C

At 20 past midnight the stokers had had enough, so the end was declared. The firebox doors left open to get an oxidised final burst to clear the air and brighten up the glazes. Then a crash cool to 1100C and at 1.30am the doors were closed and the chimney blocked up. Time for bed!

Unloading Pots - April 2017

First peek!

Top bricks of door removed to let the chamber cool from about 100C - after about 30 hours cooling from the end of the firing.

Steve dismantling the door brickwork.

The attitude of the glove towards him is purely accidental!

All the bricks removed to reveal a great firing result.

The spyhole cones 8 & 9 can be seen about a third of the way up towards the right. Just about perfect bending.

The higher cones were flat and the bottom ones almost unbent, showing the usual difference in temperature.

Some comments were made about the dominant browness of the firing, but that is what Bill likes most! The unglazed surfaces were well reduced and slightly shiny.

The experiment to test bronze casting in the kiln was an utter failure, except to prove that is not a good idea!

The mould material had blown apart - too much ash added to the clay, the bronze metal melted OK, but ran out of the cracks and seeped across the kiln shelf - but thankfully no further into the kiln.

Bill's mould in the back end of the tunnel behaved slightly better, but still leaked and the metal fused to the ceramic mould.

Debbie's ammonite sculptures, amazingly all in one piece, although one had tipped over, but survived.

After the front shelves were removed the back section of the chamber is revealed.

The top of the back section.

Some great results with the larger vessels.

Lower part of back section.

Nicely fired, except for the very lowest level.

The pots closest to the incoming flames were well toasted, but not quite as dribbly as some previous firings.

The pale glazes were spotted with ash, but not too much.

Some of Bill's class had some pleasant blues, greens and reds, those coming from reduced copper glazes.

The empty chamber

Caroline's sculptural pieces.

The woven willow had been covered with clay slip with toilet tissue mixed in to give it a bit of grip. They were biscuit fired to burn out the willow. No glazes was used.

The smaller items had been coated with a variety of slips and glazes, many using found clays and ashes.

Mark chipping away for the autopsy of his bronze moulds.

Doug's bowls, fired close to the flames to get some flashes.

Jennie's box of delights.

Steve's jug and mug.

Getting adventurous / inventive with the handles!

Unfortunately Steve packed up his splendid collection of vessels and sculptural items before they were all photographed.

Similarly Birgit's wares have missed the camera.

More of Steve's mugs.

In the background is Karen's long awaited bird bath pillow.

Some of Bill's pots, as seen from above.

Some of Bill's beakers and bowls. Very happy with dark brown shiny insides.

And spotty bowls.

Bill's bowls, jars and beakers

Bill's pots assembled

Bill's taller vessels

Tea time at last!

Report and Conclusions

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A very satisfactory result from this firing.

Strange that the temperature stuck for hours just below 1200C reading - 1260C by cones. Maybe the lack of any breeze. Maybe the lack of Steve's motivational encouragements (although that also leads to the stokers walking out!).

However the cones and glaze maturity showed a good temperature had been reached through most of the chamber. Not as hot as some firings, not as dribbly near the flames, the paler glazes were not as heavily spotted with ash as some firings.

The brown glazed insides of Bill's beakers were the best they have ever been.

The pale glazes were nicely spotted.

The copper transparent glaze turned from green to red on many pots, showing heavy reduction.

Martin's new pallet destroying device was very useful.

Comments are very welcome - email Bill Crumbleholme

Thanks to :-

Kate V for her felled nicely seasoned logs.

www.onlineshells.co.uk/natural-cockle-shells-p-3855.html

The Landlord for support and encouragement.

Pottery Class members and other potters for help filling the kiln and then firing and unloading it, especially Steve, Sam, Deborah, Birgit, Richard and Jennie.