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.

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