With our Technical Demonstrator Matt we were introduced to the ceramic kilns, how to take care of them and how to use them for firing out work, over two sessions.
Kilns are one of the most essentials tools in ceramics (ignoring all the other, more primitive forms of firing), as it turns clay into ceramics – through quartz inversion which happens at 573 °C and becomes stable at about 870 °C (depending on including fluxes).
We were introduced to the booking system used in the department.
The arrangement of kiln furniture, always having three supports under kiln shelf, and on the same place as below.
Importance of cleaning or supporting glazed surfaces, so that glaze doesn’t run down and damages expensive kiln furniture.
Pyrometric cones which measure the heat-work – the effect of the heat on the glaze inside, rather than just set temperature in an instance. Their position. Health and safety when viewing them, and when operating the kiln.
Gradual firing of the manual test kilns:
* 10% on the dial for the initial 1 hour.
* 30% for another hour, at this stage the internal temperature will be approximately 400 °C
* 50% for another hour
* 70 % for an hour
* on 100% – check the cones.
Dampers (lids) 1. open until 600°C is reached – all the moisture is released and quartz inversion began (on bisque firing). On glaze firing the damper can be closed a bit earlier, at about 300°C.
2. Open when viewing the cone and the atmosphere inside is misty (never blow!)
3. Dumper should remain closed when cooling
4. Can be open at 300°C
5. Close the damper when opening the door very slightly, at 150°C
We received further documentation for reference when needed.
I also started reading The Electric Kiln by Harry Fraser from our list of required reading, do strengthen and deepen my knowledge which is at its complete basics right now, and for future reference.