Making Pots

Bill's batch of mortaria, drying after the application internally of light oatmeal glaze - onto leather hard clay.

Another batch of cremation urns, this time with flat lids.

A pair of flared bowls.

(Don't tell anyone but they started out as urns like the ones above, but suffered from a widening so the top fell in and was cut off to leave the lower section to be opened out further.)

Loading Pots

After the first day loading, almost half the back of the chamber had been filled.

The large urns go in the "cold corner", being unglazed they still come out looking good - even if slightly underfired.

Steve and Bill take a break from a glazing session in their temporary shelter - an old horse box.

End of the second session loading.

The back of the chamber loaded, apart from a few fillers and the cones.

Steve put his wares on the top shelves, where they should get hit by the ash and suffer highest temperatures.

The lads getting ready for action!

Then they stop for a tea break and a chat.

The lower front loaded.

The lower shelves are thicker and slightly larger than the rest, so there is an overlap, which adds more complexity for the packer to cope with!

Nikki loading her wares.

Looking for hot spots!

Nikki still loading.

Special permission granted to fire some flatware on the plate rack system in the middle section.

Almost finished loading the front - Nikki left Bill to finish off the tricky high places.

Another view at that stage.

The front finished loading.

Fronde's sculptural man just fitted in on the top shelf, in front of Bill's wide bowl. Perhaps he will bring good karma to the firing!

All bricked up and front ceramic fibre filled cage hung up to cover.

Thanks to Sean for a supply of HTI bricks that have replaced some of the older door ones.

Hopefully a better layer of ceramic fibre along the top of the door will stop up most of the gaps.

So it's now ready to fire.

Firing Kiln - 4th April 2018

Tuesday evening - started the pre-heat to dry out the kiln and contents.

A cloudy, breezy beginning.

The fires were begun with large logs, well seasoned, but a bit damp round the edges. Hard to get alight to start off with, evening with a propane gas torch.

During the night, Bill slept in his car and got up sporadically to put more logs in, trying to keep the temperture below 150C to dry out without overheating the unbiscuited wares - which might explode.

8.30am the next day - the firing begins in earnest! Although Bill overslept a bit and didn't get the early starting rise in temperature - the logs used got smaller and 4"x2" timbers were also added - but they were wet to the point of rotten and did not burn fiercely.

The night had been showery with blustery winds.

Logs burning in the firebox.

Charring slowly.

The other firebox, slightly more active.

The breezy was helping the fire to burn better.

The chimney appeared to be pulling its updraught better than usual, so perhaps the rebuilt tunnel was letting in less air through the gaps.

By 9am the temperature was about 400C.

Steve posting the morning's social media report? Or maybe not?

Note how he has managed to burn his fire-resistance boiler suit arm.

Afternoon stoking.

The whole firing suffered from a slow increase the temperature. Still using fairly large pieces of damp timber!

By 4pm the temperature was 900C

Nikki looking happy after being promoted (by herself!) to the post of Catering Manager, thus avoiding having to make too many comments about the main firing.

Steve on the way to the funny farm, after one too many inappropriate comments to the ladies present. We hope his rehabilitation goes well and that he will be released back into society all the better for his retraining.

Perhaps this is somewhat lacking in tact and sensitivity towards folk with issues, but we are trying to help Steve on his own personal journey and humour seems to work for him, although physical restraint and a quick thrashing might have helped.

Nikki's photo of the kiln in the early evening.

The firebox at about midnight.

Going strong.

The Midnight Feast!

The newly refurbished pizza oven on top of the chimney tunnel worked very well, especially when fitted with a door that covered the whole front.

A very well done pizza - but not as in burnt, but cooked to a turn!

Well done to the newly created "Catering Manager" and assistants.

Thanks to Laurence for his sourdough starter, nurtured for years by Bill and producing a great pizza base. Perhaps we are in the wrong trade?

This is a graph of the firing log.

Starts at 18.30hrs Tuesday 3rd

Ends at 05.00hrs Thursday 5th.

Max reading 1175C (Although the digital reading is out of calibration - normally the cones for 1260C go over when the reading is about 1210C). So the actual max temperature in the top corner of the kiln was about 1225C. However the pots in the path of the flames will have been hotter than that.

Unloading Pots

Bill with the first pot out of the kiln after unbricking the door.

Note the cones are mainly not far bent and some glazes are immature. But the hotter regions are OK.

Close up of left hand side of chamber.

Top Cones not really bent enough, but some good results from the path of the flames.

Bill contemplating the results.

Bill almost looking happy, passing out the wares.

Still unloading.

Offerings!

Steve's new mask, mug by Fronde.

The unloading committee consider their verdicts.

Some happiness, some mild sadness.

Bill was not expected to fall on his sword!

A batch of Bill's class students pots.

Some of Bill's wares -

Casseroles - lids upsidedown now - they were fired in place the right way round with aluminia hydrate/china clay release painted round the rim to stop them sticking. Dark brown "Soup" glaze worked well.

Mortaria bowls - light oatmeal glaze appled internally to leather hard pots. Mostly slightly immature finish, so will have to be refired. Some rejects as the bottoms cracked - the more solid foot ring holds its shape, the glaze softens the middle of the base which then dries and shrinks and thus sets up tension across the base which can lead to an S crack.

More of Bill's pots.

The dark brown has worked well inside the beakers.

The light oatmeal is underfired.

Some of Sharon's pots.

Garlic storage jars worked well (No glaze!)

The white bowls were a bit bland from lack of ash staining.

The next batch of Bill's urns.

Looking very Bronze Age!

This style lid keeps a low profile.

Pleasing biscuit tones, with flashes of ash to break it up a bit.

Dales tiles and cups

Caroline's sculpture.

She uses found clays and ashes from her wood burner, with other stuff added.

Top of one of Caroline's pots

One of Birgit's bowls, wax resist with Shiny White glaze - lacking ash speckle and slightly underfired.

More of Birgit's bowls, wax resists with Fiord Blue glaze.

Jennie appraised some the wares.

The eggs in the bowl were placed in sawdust inside Bill's sealed urns. Not bad for a first attempt at a new technique! The tops were slightly smutty.

Richard - happy with a bowl. Lacking ash speckle, but still round!

Jennie's class students' pots

One of Fronde's mugs. Nice ash effect to highlight the decoration.

Emma's bowls and mugs.

Mugs placed in a nice hot spot, so mature glaze and good ash speckle.

One of Bill's dishes - which benefited from being at the very top of the chamber.

Same dish, from lower down. Nice profile!

Closer view of one of Bill's cremation urns.

Bill's pots.

The urns with larger lids were at the bottom of the back section, with more reduction and ash enhancement than the ones at the front of the chamber.

The bucket of heated nails is from a previous firing's fireboxes. Suggestions for what to do with these and many more would be welcome! Together with the clay impressions from the shells used under most of the pots.

Fronde's sculpture and mugs.

More of Bill's pots.

Caroline's collection.

Deborah's bowls.

The unglazed rims give a great contrast against the white glaze, which picked up a speckle and blush from being in a hot path of the flames.

One last view of an urn!

One of Dale's cups - just how things should come out!

Report and Conclusions

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So a bit of a Curate's egg firing - OK in parts!

Better than Bill hoped for at 5am at the end of the firing!

Generally too cool and not enough ash staining, but some great pots from the hotter places and the urns did not need the higher temperatures, being unglazed. The Brown "Soup" glaze matured well alongside other glazes that were left rough surfaced.

Technically, the biggest problem was having damp (in some cases rotten) wood - which took too much energy to dry out in the firebox before giving up the burning energy release.

Some of the timber was trunks and branches, which should have been split up more to enable the sap wood to burn, rather than the whole covered in bark, which tends to char into charcoal then burn slowly.

The overnight preheat was not hampered by these issues, indeed they helped keep the temperature moderate while the kiln and contents dried out.

But the early morning gearing up did not take off as quickly as usual, Bill felt the need to use the tree like timber up, rather than wasting smaller better wood on the first 1000C rise, as he was aware of a lack of that better timber - needed for the final stages.

Then the afternoon rise was slow as well for the same reason.

When smaller cross section drier wood was used the temperature increased much quicker. But even some of the pallet wood was damper than usual.

The top half of main chamber was mostly in negative pressure, with air being sucked into the chamber rather than smoke and flames being pushed out. This means the chimney was pulling better than usual. The seal at the top of the door was made better, which stopped flames escaping there so much as usual.

If the chimney pull was too strong it would extract the hot air out of the kiln chamber before it had given up enough of its heat.

Perhaps the passive dampers at the bottom of the chimney should have been removed early on - one was tried in the evening, but it made no perceivable difference.

The grates in the firebox had been altered, with bigger gaps between the ember catching rack cross pieces. So more primary air could get into the kiln from below the doors and pass up through the burning timber. The build up of unburnt embers was reduced by this.

The rebuilt tunnel between the chamber and the chimney seemed to still have some gaps, but perhaps not so great an area as before. So that would help efficiency as well.

It was fairly windy at times, which probably helped the chimney pull more. The two fireboxes also burnt in different ways, as one had the wind blowing into it and the other was turbulant - maybe with air being sucked out of it.

The atmospheric pressure was lower than usual, which is meant to help the chimney pull.

One suggestion was that we had upset our ancestors or the gods of the kiln somehow and they were not smiling on us! Perhaps more libations should have been offered?

One very high point of the firing evening was the pizza production, our newly appointed catering manager and her assistant did a splendid job! Thanks also to other folk who brought us offerings.

Comments are very welcome - email Bill Crumbleholme

Thanks to :-

Sean for some clean HTI bricks, to improve the door building up.

David for a supply of seasoned logs and use of the horse-box.

A local forest for some deadwood. Potters have been prosecuted over centuries for collecting wood from common land! But at least we don't dig pot-holes in the local roads looking for clay!

Penfold Pallets of Winterborne Abbas, Buildrite of Broadway and Travis Perkins Weymouth for broken pallets.

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

http://www.onlineshells.co.uk/washed-flat-scallop-shells-p-3427.html

The Landlord for support and encouragement.

Pottery Class members (Bill's and Jennie's) and other potters for help filling the kiln and then firing and unloading it, especially Steve, Nikki, Richard, Sharon, Sarah, Birgit, Dale, .....