Wood Fired Pottery: Old Methods, New Technology

The latest craze, among amateurs and professionals alike, is actually as old as pottery itself. Here's a look through the ages at wood fired pottery and kilns.

In the beginning, clay was primarily used to create non-utilitarian objects such as small figurines - animals, people, perhaps images of gods. Ten thousand years ago, coincident with the rise of agriculture, came the need for means of storage. Clay pots were the answer.

Firing of pots may have been discovered more by accident than design. Certainly, once discovered, the practice became widespread. Firing pottery enhanced its durability, though initially not much, and expanded creative opportunities for artisans.

Throughout the centuries regions of the world came to be identified by their pottery. Archaeologists still use the evidence provided by potsherds to identify ancient settlements, civilizations, and even early trade routes.

Initially, almost any combustible materials would be used for the firing. Because they were plentiful, most common were wood and bone.

Early kilns were little more than holes in the ground, piled with pottery and combustibles. Temperature control was problematic. Moreover, the combustibles could rarely reach or sustain the high temperatures necessary for glazing.

The evolution of pottery kilns took many centuries, even though potters recognized the need to find ways to create and sustain these high temperatures. Add to that, kilns had to be developed which had substantial capacities.

Beehive-shaped kilns with dampers and fireboxes were eventually developed. Then came climbing kilns which had multiple fireboxes and huge capacities for pottery. About the same time advances were also being made in methods of insulating the kilns and regulating temperatures.

The use of natural gas, propane, and later electricity brought economy and uniformity to firing of pottery. With potters today these are the most popular kilns in use. Thy have enabled the development of new glazes and much more durability.

In recent years, partly because of environmental concerns, the use of non-renewable resources (gas) and the high cost of electricity, potters are once again turning to wood fired kilns. They now, of course, have the advantage of design improvements. Use of firebricks is de rigeur, for

example, to withstand very high temperatures and retain the heat in the kiln.

Wood firing remains a lengthy, labor intensive process. Depending on a number of factors--kiln size, desired temperature, and system of delivery--a firing may take twelve to thirty-six hours.

The larger the kiln, the longer the firing takes. For some Japanese potters who have very large kilns, a typical wood firing can take three days, with potters feeding the fire in shifts.

While the choice of wood usually depends on cost and local availability, as a rule softwoods such as poplar and pine burn more quickly, but hardwoods such as oak burn longer at much higher temperatures. Potters report success with both; however, it should be pointed out, the desired

finishes dictate the necessary temperatures and length of firing.

Potters, now armed with some technology and a vast inventory of possible glazes for finishing and possible materials for clay mixes, can and do experiment. For example, varying proximity of the pots in the kiln to the flame in the firebox can result in very pleasing, unique finishes. The objects may be uniform in design but each finish can be "one off", no two alike.

As for technology, now commercially available are pyrometers designed to measure high temperatures inside the kilns and pyrometric cones, composed to melt at specific temperatures. These enable a potter to monitor temperatures inside the kiln.

Whether the popularity of wood fire kilning is simply a response to a faddish market or whether its economic, environmental, and creative values will prevail over the long term is moot. For sure, age old methods are once again proving their value.

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