Friday, January 1, 2010

A perfect cone 9

Happy New Year.

I am 'feeling the joy' of a cooler day in old Melbourne town after a scorcher yesterday, and nursing a fairly gentle hangover from last nights festivities - a good start to the year all in all.

Better still is the grand news that last year's firing difficulties should indeed be a thing of the past. The solution to my kiln's over eagerness to race to and beyond her programmed temperature was a simple matter that I am now somewhat embarrassed to admit to but will relate for the greater good.

The protrusion you see here is called a thermocouple and it measures the temperature in the kiln to inform the controller when to power up.

And this is exactly how it should appear through the kiln wall.

Over time, presumably with each open and close of the kiln door, Amber's probe has been wiggling its way backwards into the wall cavity. Not the correct place to be reading the kiln temperature!

The solution - gently push it back in and secure this section which holds the probe in place from the outside.

Simple! I can't begin to tell you what a relief this is. Over firing is not only concerning for the damage it could do to an electric kiln but also the effect it has on the work being fired.


This iron based engobe is a beautiful rich eggplant colour when fired to the right temperature.








But if it is fired too high the redder tones burn out leaving this not so pretty yellowy-brown.







Higher temperatures also invite 'warpage'. Which may explain why I have had a recurring problem with handled forms. Prolonging the time porcelain cups are in a pyroplastic state has resulted in the weight of the handle dragging the form to one side. Like this...


And then there is the blistering of other clay bodies...

I could rattle on but thankfully I am ready to move on and so very looking forward to a fresh start in 2010.

But first a holiday!

2 comments:

Anna said...

Hi Sophie
thanks for posting the answer to your problem.
I write a newsletter for a community pottery group. Would you mind if I quote this entry as we have an electric kiln members can hire.
Regards
Anna

Sophie Milne said...

Please do Anna. More than happy if others can learn from my mistakes!