KILN BUILDING IN VICTORIA, SOME PERSONAL REMINISCENCES
by Hatton Beck.
My first experience of pottery was in 1906. I saw my uncle throwing flowerpots, and was lucky enough to see his wood-fired kiln in full fire. It was quite a spectacle. Flames seemed to be coming from everywhere; from the top of the kiln, from out of the fireboxes, and glowing through the cracks in the kiln wall. I can imagine the spectacle of the Nigerian grass fired stacks of pots. He taught me the importance of good chimneys; a lesson I never forgot.
The first pottery kilns were used to fire bricks. I understand that the principle was much the same as that used in the early lime kilns such as you can still see in the cliffs of Waratah Bay (Vic.) for which a vertical hole was dug from the top of the cliff as close to the edge as possible down to beach level, where an opening was made. Alternative loads of lime and wood were fed into the hole from the top opening. This was set alight at the bottom opening
The early brickmakers formed the unfired bricks into a stack, leaving spaces between them for the heat to circulate. A brick firebox was built beneath the stack. In the 1950's, a man in the pottery district near Ipswich (Qld.) built his house with bricks made and fired like this, so I have seen the original method actually used.
When I first visited Mr. Merric Boyd *1 to find out how to make pottery, I was amazed at the lack of information available to the amateur potter on the construction of small kilns. Making kilns on a small scale doesn't always work out because to get fuel to a high temperature you need quite a volume of fire, unless there is a very efficient draught system.
To prove this point, at Brisbane Tech, Carl McConnell *2 made on the throwing wheel, a kiln for ceramic jewellery, which we fired to 1100 degrees Celcius with woodchips. This led to such kilns as the telescopic lens furnace by Stravinski and to the ultimate in element kilns, made by Uscinsky; a round kiln, eighteen inches in diameter, with an element embedded in zircon. Unfortunately much of Uscinsky's knowledge was lost when he died, although I do have a photograph of this element kiln and the kiln itself may still be in existence at Mount Dandenong.
But now, back to the beginning .
The first kiln I built was coke fired and about three feet high. It was just a plain box with 4~.2 inch (11.5cm) thick walls, and firebars at the bottom for draught. On these stood two firebrick boxes (called saggars), obtained from a commercial pottery. A sheet of corrugated iron was placed over the top. This burnt out during each firing. The bricks, which formed the kiln's walls, were loosely stacked and the gaps between them ensured an adequate air supply for the coke fuel. Later, we tried to build a larger kiln, which turned out to be unsuccessful because we cemented together the bricks in the walls
My next attempt was based on the principle of the old wash?house copper stand; the roof arched over with bricks and firebars sticking out the side of the kiln. Unfortunately too much heat went up the chimney so we made the entrance to the chimney smaller which was a better success
Next came a simple updraught kiln, with fireboxes butting onto each side of the kiln and a hole in the top of the arched roof
This was altered in shape as time went on, by trail and error. But it was rather unreliable when coal was used because the fireboxes coked up and often the temperature could not be raised to the desired level. Used fuel has then to be raked out and fresh coal used
This led to a down draught kiln with the fireboxes entirely outside the chamber. The heat was channeled through holes in the wall of the kiln, up to the ceiling and them down through the kiln chamber. Heat was drawn into a chimney through a square hole at floor level at the back of the chamber to a chimney of bricks topped with 6 foot extension of 9 inch diameter iron pipe, thus creating a strong draught.
The building of chimneys gave us much trouble as we did not understand how efficiently they had to be designed in order to create draught. We had no book for guidance.
Eventually it was a success, and this led to the use of briquettes, which turned out to be very efficient and clean. This was our first experience with a controlled method of fuel handling, but even so, we had to notify the fire brigade every time we did a firing
When I got married, my wife fired early stages. (At this time I was working at Evans Brothers tile works). She began by loading six briquettes every quarter hour, then ten, and finally at full fire, twenty briquettes every quarter hour. The kiln's efficiency depended upon careful timing; loading fresh fuel at the right stage of the burning of the previous load
During this period Mr. Gilbert *3 was helping us (and several other people) with brick work. He perfected a coke kiln, which was used by several potters. This consisted of a central muffle of firebrick slabs with an opening in the front wall, which was sealed with firebricks during a firing. Coke was loaded into the furnace through four small holes in the arched roof. At the top of the roof was a chimney hole.
A gas fired kiln was tried, using town gas, but even when designed as an updraught kiln, it was not economical at anything higher than a low earthenware temperature, so the power blown principle was introduced to the updraught kiln. The building of cone burners was the first problem, but we got help from the gas company.
We first tried oil (car sump oil and water drip method) but an eight feet long (2.44 metres) oil kiln we built at Murrumbeena was very temperamental. Some very good large pieces of ceramic sculpture were fired in it though, some at temperatures of up to 1200 degrees Celsius
I knew of a very efficient oil drip kiln from America being used in Queensland, but for us the power blown gas sort was the answer. The introduction of liquid petroleum gas created the most efficient fuel source.
The first electric kiln we had was a metal heat treating furnace with a voltage adapter to control the rate of heating and therefore lessen the likelihood of cracking the pots. If the kiln was big enough to accommodate several elements, separate switches on each element would control the rate of heating. But a better solution was the thermostat pyrometer with a no?volt release switch and a Simmerstat *4 switch
A thermostat is a rod which is pushed into the kiln. It has two wires of different metals joined together at the tips. The expansion of the metals occurs at different rates, forming a small electrical impulse that is sufficiently magnified in the pyrometer to move an indicator on the dial to operate a tiny switch.
In the early days, damage to elements by oxygen reduction and gases from colors and glazes was a problem at high temperatures. High temperature insulating bricks were not available. Diatomaceous earth bricks would not stand the heat inside the kiln. So I made a mixture of diatomaceous earth, cement fondu and some other materials, cast in moulds to form racks to hold the coils. This was good enough for earthenware temperatures.
The first electric kiln I made had coils of elements fastened to the walls with staples made from element wire.
The making of my first pressure gas kiln, though, was quite an adventure. I used a blacksmith's blower, which was alright until the kiln got to a certain temperature : then it exploded, blowing out the kiln door. So I got a higher pressure blower (adapting large commercial kiln methods to small kilns was always a matter of trial and error).
I sold this kiln in 1945 to John Perceval and Arthur Boyd. My first effort with a power blower oil kiln was for a man who had a pottery at Lorne (Vic.) and, it being successful, we built another one for Mrs. (Greta) Behan *5. I used one to make canteen cups during the Second World War.
A big problem for early potters was the scarcity of materials. The commercial Potteries could import them from England, but until H.B. Selby & Co. started to stock materials, we had to make our own glazes, with 50% red lead, fine sand, lime (calcium carbonate), whiting and clay, coloured with copper, iron, cobalt and chrome. According to modern medical research we must have poisoned thousands, but red lead when properly fired is quite safe. Only when insufficiently fired is it unsafe.
My first clay was dug from my backyard in Oakleigh, the great brickworks district. It was wonderful clay for throwing.
Modern potters should remember all these troubles with kilns, equipment and materials
when judging the efforts of early potters. We did not have any books at all until
Searl's 'Clayworker's Handbook'.
Written by Hatton Beck, July 1978.
Edited by Peter Timms. Further editing by Colin Smith.
1.Merric Boyd. 1888 - 1959. Made pottery in Melbourne from 1911, exhibiting his work regularly in exhibitions throughout Australia. Merric, father of Arthur Boyd, is widely regarded as Australia's first significant studio potter.
McConnell. Born Chicago 1926, settled in Australia (Brisbane) in 1948.
3.Mr. Gilbert. A builder who assisted Merric and Arthur Boyd with studio and kiln design. He later established his own pottery at Murrumbeena (Vic.) where he worked during the 1940's and 50's.
4.Simmersat is a tradename.
5.Greta Behan. Born in the 1880's, Behan made stoneware in the 1930's which she sold through a retail outlet in Lorne (Vic.).