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 Modern practice in kiln design for small operations such as DePauw's ceramic program usually suggest a single chamber down-draft design using natural gas or propane as the fuel. The "down-draft" design refers to the way hot combustion gases are caused to circulate through the kiln. The simpler up draft method used in the shard roof and arched roof kilns illustrated here have one disadvantage - - since the flame is introduced at the bottom and exhausted out the top, the bottom of the kiln is always somewhat hotter than the top. This difference is not enough to be a problem unless the potter is using glazes. Glazes tend to melt at very precise temperatures and they will not have the appearance the potter wants unless their maturing temperature is reached and not exceeded. A down-draft kiln solves this problem by causing the hot gases to circulate around the kiln's interior before exhausting instead of going straight through as in an up-draft kiln. A down-draft kiln will accomplish this by deflecting the flame up into the kiln and then sucked back down by the draft of a separate chimney that is connected to an opening in the lower part of the kiln. Modern practice also includes a device called a damper which acts as a valve to control how fast gases pass through the kiln.kiln under construction

The efficiency of modern kilns has also been greatly improved by the use of new refractory materials. In the past kilns had to be made of dense heavy bricks that absorbed much more heat than the pottery being fired. They were also very poor insulators that wasted even more energy by radiating heat into the surrounding environment. Kilns are now commonly built with what are called "Soft Bricks". These are bricks that are made from clay that has been "whipped" much like whipped cream. A large amount of air in the form of small bubbles is mixed into the clay before it is shaped into bricks and fired. These brick weigh only about one third as much as a "hard" brick and because of the air pockets are good insulators.
 Illustration of a common type of down draft kiln under construction. The veiw is from the rear showing the stack and slot for the damper.

In recent years a new type of ceramic fiber has been developed that has very high insulating properties and is light weight. This material is produced in a blanket form much like the fiber glass insulation used in houses.

The use of natural gas for fuel and kilns made of modern insulating materials has vastly simplified the process of firing ceramic objects. If our glaze kiln were made of "hard" bricks and used wood instead of gas for fuel, the firing would probably take 24 hrs. instead of 8 and consume an enormous quantity of wood.

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