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Paul Soldner is a wide-ranging potter, teacher and workshop leader. He divides his work and residence between Claremont, California and Boulder, Colorado.
The use of oil as a fuel for firing pottery kilns has interested me since 1964. Prior to that time, I had experience only with gas and electricity as fuels. With my move to Aspen, Colorado I was suddenly thrust into a situation where natural gas was unavailable and the price of propane was prohibitive. So I began to look to oil as an alternative. About this time I had also been asked to investigate oil as a fuel for firing in underdeveloped countries. I first met this need from teaching I had done for the Peace Corps while training volunteers to improvise pottery firings in countries with limited resources of gas, wood or coal. Oil in some form was found to be the most universally available fuel throughout the world.
The difficulty in burning oil is that it is a liquid which needs to be converted to a gas before it will burn well. The making of this liquid oil into a gas can be accomplished in several ways. One method is to atomize the oil into very fine droplets. This can be accomplished by pumping the oil, under high pressure, through a small orifice. This will result in a fine spray and is the method used by the common home oil furnace burners as well as by large steam heating and generating plants. However, the machinery involved is complex. Also, the orifice is small and so is subject to clogging, thus requiring much maintenance. There is another factor as well: the fuel must be as thin as possible and this eliminates the heavier and therefore cheaper types of oil. Another method of burning oil is the familiar weed burner. Here the oil is heated, by its own flame, in coils until it vaporizes into gas. However, the boiling oil develops enough pressure so that it must be contained in a pressurized tank to prevent vapor-locking in the supply lines. This system does work well when there is no electricity available, but some means of pressurizing the oil tank is necessary. This can be accomplished by a gasoline driven air compressor or by a hand pump. A minor inconvenience of pressure burners is the fact that they must be operated "wide open". This results in a very hot, oxidized flame. Therefore, to prevent a rise in heat which is much too fast during the early stages of firing, the burner must be located some distance from the burner port. Gradually, the burner can be moved closer to the port as the kiln heats. The clogging of the orifice. is also a constant problem and the building of a pressure requires specialized engineering.
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