Tuesday, November 13, 2007
So the "old" elements seem to be holding up meanwhile,with firings taking around 7 1/2 hours on average to top temperature [cone 10 1/2 over],using 2 programs to grow 6-7 rings around the crystals,with pleasing results,few duds,no breakage,and only minor [but persistent] damage to the kiln- chiefly gobs of glaze that spill over their too-shallow catchers and eat into the soft-brick kiln floor. When the kiln is cool,it is fairly easy to pop these globs out with a screw-driver [taking a bit more floor with them]. I'm stuffing the holes with ceramic fibre temporarily,but will need to think of some mixture to fill them with-probably ground brick with some NaamanSet refractory cement to hold it together.
Friday, November 09, 2007
Twenty Firings and a Thermocouple
Kiln # 21 yielded its treasures this morning-one big fat vase that started to slump a bit but produced a good show of crystals,and 4 mezuzah covers in the silver nitrate version of the glaze,which seems to work better than other colours on this shape. As the kiln was cooling,I noticed the dreaded "thermocouple failed" readout: you might remember that I started this round of crystal firings with a gleaming new thermocouple- 20 firings is pretty lamentable working life for a $100 item. Mind you,the Evenheat Thermocouple is a rather weedy affair,with a metal tube instead of a porcelain sheath [metal? at 1300 degrees?]
Luckily [the war-cry of the Yekke] I have a spare. Before fitting it,I checked with another pyrometer [also a spare...] to see if Evenheat's thermocouples are regular R-type [or possibly S-type,they're similar]- which they seem to be. On Sunday the nice man from Madid is bringing me three spanking new thermocouples [like the angels who visit Abraham in the book of Genesis,each has a specific task- one is for Meir's new anagama,one for our salt kiln,and the last might be for apprentice Yahel,who plans to build a gas kiln in the near future; otherwise,it will be [you guessed] A SPARE. I love spares.] I think I shall ask him to make me a proper thermocouple for the electric kiln. In case you are interested,a grown-up made-to-order thermocouple [30cms long porcelain tube,lots of expensive platinum wire] will set you back 1400 shekels,not to mention V.A.T. That's for a kiln with a 20cm thick wall-the little electric kiln needs much less.
Sunday, November 04, 2007
Friday, November 02, 2007
Sydney also pitched up for a visit [it's a sociable day] and suggests that I wind my own elements. Inevitably,he has a winder and a pile of Kantal element wire [it's even the right gauge]- he recons I could save $180 a set. Something to ponder.
By the way,this Camino browser really does seem to work much better than Safari with my Apple- but maybe you all knew that already.
I'm trying to load the video via Camino instead of Safari....
Yes! Persistence,that vital [some would say the only] requirement of the potter,pays off.
For the technically-minded,this bowl is thrown using 480gr. clay- what Bernard Leach called a GP bowl [General Purpose].
Kiln # 17: just when you feel you might be getting towards some sort of feeling for these glazes,your kiln elements start to perish- this firing took 7 1/2 hours to top temp,up from 4 1/2 for the first few. This,of course,affects the way the glaze behaves in parameters not indicated by even the all-knowing pyrometric cone- for instance,the longer the glaze is in a molten state [say,the last 200 degrees] the less material is available for growing the crystals...
Let's say I manage to squeeze another 3 firings out of this set of elements. Replacements will set me back close to $200- which means $10 a firing,or $2 a pot.
Glodie,Reuven and Naomi [new daughter] have just arrived for a visit,so bye for now...
Thursday, November 01, 2007
My Other Kiln is a Laser
The joys of wide wide-angle lenses.The rebuilt gas-kiln is just about ready to fire,sporting a new flue,new [and arched] roof,new door-lining and seal and two new slices of wall where the old ceramic fibre boards had buckled and warped into the flame-path. This project used all 13 of the boards [90/60/2.5cms.] I had bought,with next to nothing left over. Now to find out if it all works...
I got roped into a music video today- Tal Segev [a new one on me,but Eliav assures me that everyone else knows him] with his merry film crew posed meaningfully around the studio while I threw porcelain bowls.The song is called "Yaakov",I'm not quite sure about the storyline. Supposedly it should hit the cables in a couple of weeks.
Yesterday's kiln was less than stunning,but quite interesting- either the glaze was too thick,or the firing a touch too cool,or maybe both,but possibly neither. I'm having another go today with a kiln called [rather imaginatively,I thought] #17.