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Use clean shelves
Shelves with glaze spills need cleaning as the glaze can eat into the shelf. Grind the glaze flat to the shelf using a flat diamond wheel on an angle grinder. It is not the perfect solution but you can get away with it by using a couple of coats of kiln wash on the shelf.
There are different views on the number of props to use. I use 3, but some prefer four. Most of my shelves are more than 30 years old and as new after some 500 plus fires using three props. All props should be in line one above the another. Staggering the props can cause bent shelves.
It is not ideal to use three and four prop setups in the same fire.
I occasionally use four props for large items when the centre prop is in the way. I use a four prop method once only and on the top of the load - so minimal weight is transferred away from the three prop tower. With the four prop method, you need to check for shelf rocking on three props. Therefore, the 4th prop will require packing. Pack with fibre paper for small variances or if shelves are too wonky – use clay wads.
When I’m repairing kilns, I see many full-sized shelves in use. First, this is hard on your body and as they are heavy require two people to place in the kiln. Half shelves are a better option and make packing the kiln much easier.
Select items of similar heights and load the half shelves on three props up the back of the kiln first. Then load the other half at the front. Try to stagger shelves to create good airflow through the kiln.
NB shelves 400 x 400 and 450 x 450 can stay full. Shelves above 530 x 530 should be cut in half.
Packing the kiln
Again views differ on how tight to pack the kiln. Some like a good gap between items. I pack my bisque tight to the point the things are touching and place small pieces inside large pieces. Obviously, we do not do this in a glaze fire; however, items are placed close together. While packing, keep in mind your cones and the shelf required at peephole level.
Starting the kiln.
Later model electric kilns are more straightforward as you can now select the program, press start and almost go to bed. In a bisque fire, initially, leave the bungs out. Around 350°C – 400°C I put the roof bungs in. If possible, put the door bungs in at 650°C – 700°C or do as I do and leave the door bung until the following morning when the firing has finished, and the temperature is still above 700°C.
Glaze firing in an electrically controlled kiln can have all the bungs in by 400 deg as by then the moisture has gone.
Unless you have an automatic gas kiln – manual support is necessary for the whole firing. Temperature control and burner control is every half hour with the use of a manual pyrometer and cones at the end of the fire.
Ken Ison Pottery has four kilns; One electric and three gas. The raku kiln is only used a few times a year, while Sparky, Opal & Hercules are fired several times a month. On the calendar you will see the firing schedules.
SPARKY does the night shift
The newest kiln is sparky with over 150 fires to date. Sparky is a workhorse and is fired several times a month. The automatic controller ensures it is not necessary to ride shotgun as with the gas kilns. Sparky does all the bisque firing and low temperature glaze fires.
OPAL is quick fire.
This kiln with 300 plus fires is originally from Weipa and fires our popular Opal glaze. It is a two burner gas fired top loading kiln. Opal fires small loads and does the reduction firing for: Deep Sea, Eucalyptus & Opal.
HERCULES is jack of all trades
This 504 litre 22 c ft four burner gas kiln does the bulk of the oxidation fires. This kiln came from Vanuatu about 40 years ago and is still in excellent condition. Hercules fires our Avocado, White Iron, Pacific Green, Pacific Blue, Chocolate, Charcoal & Terracotta glazes.
All the kilns are well maintained, in excellent condition and will probably still be firing in another forty years.