Thursday, 3 June 2010

Tuesday, 25 May 2010

soda kiln firing

Kiln firing-  Saturday May 22nd. Opened Monday.

Here is the kiln packed and ready to go. The pots are not biscuit fired - one firing only. All the pieces are coated with slips that favour  soda and salt glaze.  I placed 4 "draw rings" seen in the middle.  These are withdrawn periodically by the use of an iron bar through the spyhole which will be built in to the door of the kiln and which tell me the degree of sodaglaze build-up. 6 cones are placed behind - for temperature readings from 920 deg C to the peak of 1310 degC.  My digital pyrometer is ancient, clapped out and totally unreliable so I must rely on the cones! The two plugs either side of the door are soda spray ports -two more at the back.

Kiln at peak of firing - spyhole brick removed. temp 1300 deg. firing took 14 hours from start to finish - used wood up to 900 then switched to gas firing for remainder. Much easier to manage soda spray that way! It was a hard day - the hottest of summer so far - and with the heat of the kiln....  The kiln has two tiny fireboxes for wood-firing - very effective and responsive. All the air is preheated through
ducts around the fireboxes- the secondary air especially useful, coming into the kiln behind the bagwalls through rows of 1" holes, and good for cleaning up excessive smoke. When the fireboxes become clogged with embers after a few hours, it is an easy thing to switch to gas for a while to let embers burn out.

Of the two jugs I showed earlier, the brown one did not make it into the kiln through lack of space, so this one is similar but with a brush of titanium based slip - combed through to the brown slip.
The same jug viewed  from both sides. - the turquoise colour is the "quiet" side, facing away from the direction of flame and soda vapours, the other side got  more of the "action"!  A lot more soda - quite a difference! but this is what soda-glazing is all about!

There were a few good pots but quite a lot of Duds! A lot of the slips went on too thickly for the soda vapours to break up into interesting textures. Quite a lot of brown fudge!  So - much thinner next time....and I really must resist the temptation to use large pots for testing new slips - not a good idea! - wrecked  a few decent jugs that way.  The blue slip was poured over the "leather hard" jug and this results in the darker lines and streaks which are not always attractive - they would be much better dipped into a large bin of slip.  I will mix up some large bins of slips for next firing.

Here are some of the better pots from this firing:

slip brushed on with a 5" emulsion brush.

brown slip combed through to paler body with temoku glaze over.

T with bonfire-ash glaze. White slip trailed decs.

Sunday, 16 May 2010

continuing work on the big jugs.

Have just decorated the jugs I made earlier. They have been coated with coloured "slips" made from clays felspars and other things!  After leaving to stand for a few minutes I swept over the surface with a "slip comb"  This I made from a rubber kidney with nice rounded teeth cut into one edge.  It takes quite a bit of practice to do well.  It has to be done quickly and in leisurely and barely conscious manner - a bit like the way you spread butter on your bread whilst listening to the Archers! My first attempts were not good - too nervous and hesitant.  I hope the firing in the Soda kiln next week will do them some favours. More about the kiln later.  And I will show the jugs as they emerged from the kiln.

Friday, 30 April 2010

todays activities

Today is my first time on the blog, so I might as well say what I have been up to today! I have been putting handles on the big jugs I threw on Wednesday - 4lbs and 7 lbs. I still use the old imperial weights! - my faithful old grocers balance still serves me well after many years - and will still be good for a hundred more! I made these ostensibly traditional shapes with my customary anxst! How to achieve some sort of equilibrium between the "useful" and the "beautiful" Are jugs really "useful"? Honestly, I mostly use one of my big jugs for topping up the car radiator - they are really handy for that sort of job.

Anyway, next thing is to think about whether or not to apply decoration before they go into the Soda kiln - about which - more later!