The Elusive Cone 6: A Salt Glaze Firing

Events

The rare opportunity to have pots fired in a salt glaze kiln attracted tremendous interest from members with the pots submitted exceeding the capacity of the kiln; ample reason for organising another firing in the not too distant future.

Several postponements caused by wet weather frustrated attempts to load and fire the kiln. However, armed with conflicting advice from metrological experts it was decided to brave the elements and stage the firing on Saturday, 13 September 2003.

Richard Stratton and Flora Christeller had repaired the bag wall of the kiln in advance of the firing and Flora had supervised the filling of a 200-litre diesel fuel tank. The latter, as we were to discover to our cost and inconvenience, initially appeared to have attracted some untoward interest. The kiln was loaded by Wayne Blackburn, Mike Atkins, Rosemary O'Hara and Flora Christeller in advance of the firing day.

For some the day started at 6.00 a.m. Attempts to fire the kiln were frustrated when it was discovered that the 200 litres of diesel had mysteriously disappeared. The first thought was that it had been siphoned off by a person or persons unknown whose parentage was called into serious question. Another and less sinister or interesting explanation was that a leaking tap had caused the loss. This discovery set in train a routine for the rest of the day, namely a succession of visits by Roger Pearce, armed with a variety of containers, to the nearest service station. The nimble Roger spent the greater part of his day clambering up and down the side of the fuel tank decanting and filtering 5 litre quantities of diesel into the tank.

Built in the early nineties, the kiln had not been used for some 2 to 3 years. This coupled with the persistent wet weather meant that the kiln was sodden. Large quantities of steam issued forth from every possible vent in the structure giving an appearance more akin to a steam engine than a kiln. This had the effect, in combination with other factors, of slowing the firing considerably and causing excessive fuel consumption. Some 252 litres were used instead of the estimated 200 required. Extensive application of fire clay and ceramic fibre plugs helped to quell these revealed sources of heat loss.

Periods of inevitable tedium while the kiln's temperature slowing increased were relieved by, among other things, the enterprising Mike Atkins. He installed a temporary but highly effective lighting system as well as making a clay fish in a mould he discovered in the premises once used by the bricklaying apprentices. During visits before and after his duties for the day as an air traffic controller, Mal Sole contributed some clay chips to Mike's masterpiece in progress, now christened "fish'n chips." Wayne, whose laconic style and sage comments enlivened the occasion, found that his role had expanded well beyond what he had originally envisaged. This had included ferrying the pots from the rooms and loading the kiln. His extensive knowledge of oil-fired kilns became apparent and useful as the firing progressed.

The Lotto PowerBall record jackpot of $17 million that had to be won that day did not go unnoticed. A syndicate was quickly formed to enrich itself from the inevitable outcome that its members would share the first division prize.

The refugee like establishment had a number of visitors during the course of the day including Beryl Buchanan, Hazel Calderwell, Jan Pearce, Lynne Ross and Jenny Shearer. Flora's grandson, who recalled visiting the kiln as a child, also paid a visit. They shared some of the privations endured by the team including cheese and biscuits and when pressed - wine and coffee. Those who stayed the distance partook of a Chinese take-away banquet in the evening.

As the day progressed there were increasing concerns about the slow temperature gains and frequent observations were made of what was issuing forth from the flue: smoke, its colour and the absence of smoke; and flames and their length and colour. The kiln was not firing efficiently and it was concluded that apart from its sodden nature and a broken damper, a possible cause was that chimney was partially blocked.

John Wineera, a salt glaze practitioner, joined the gathering in the evening to supervise the salt phase of the firing. The pyrometer sat doggedly well below the temperature target of 1300 ° C. Optimists who detected sudden temperature increases were dismissed out-of-hand as being seduced by the error due to parallax. The drooping of Cone 6 became the elusive but significant stage in the advance to the target temperature. John frequently observed and commented on its state of erection as the evening progressed.

Eventually Cone 6 collapsed, the pyrometer nudged 1300 ° C or thereabouts and the frenetic process of the casting of the salt began. The feeling of newfound elation quickly evaporated as the burners extinguished themselves. The fuel-line was quickly disconnected and brave souls, already stinking of diesel, blew from either end of the fuel-line to clear the blockage. More diesel was added to the tank, the fuel-line was reconnected and much to everyone's relief the burners roared back into life.

Throughout the entire firing Flora (80 last birthday) shared her immense knowledge of salt glazing with the novices present, actively ministered to the kiln and showed no signs of the fatigue that was beginning to creep up on people many years her junior. We were all tremendously grateful for her contribution.

With the test rings checked progressively for any subtle changes in the quality of the glaze and the supply of salt exhausted, the camp was dismantled in light rain and the kiln closed at 2.15 a.m. - Sunday. And so to bed!

Tuesday dawned, the kiln was opened, pots removed and previous firing records were examined. The firing had been excessively long and the cones confirmed that the optimum temperature had not been reached. The results were a mixed bag but some pleasing results were achieved; sufficient to kindle interest in another firing.

Alan Ross