Firing Techniques Update

Pit Firing

it firing can be termed a 'primitive' firing technique, although this is not meant in a derogotory way. The word 'traditional' can certainly also be used in the case of many cultures, that were amongst the first to discover this simple firing technique. It is still widely used on many continents today, but it the sort of thing you can easily do in your own backyard and it enjoys popularity with some studio potters. Early cultures found clay in the ground and must have discovered its fired qualities by accident, probably discovering some burnt clay in a camp fire. This very basic firing then evolved into the pit-firing.

Not all clays are suitable to use in such a firing, especially the more refined types available from suppliers. Additions of grog 'open up' the clay and make it more resisitant to heat shock. Clays dug directly from the earth may be suitable 'as is', or might profit from additions of grog or volcanic ash, which also resists severe temperature differences. If using a commercial clay, get a clay suitable for raku firings. The best color results can be achieved with iron bearing, or red clays. It is a good idea to bisque fire the work first, as this helps to prevent shattering and cracking. Pit-fired work is usually not glazed but rather burnished before the bisque, or decorated with washes of black or red iron oxide, copper carbonate and mixtures of these, after bisque. Color effects can also be achieved by spreading oxides and carbonates around the pieces (particularly copper carbonate), which volatilise and result in flashes of color appearing on the fired work. Similar effects can be achieved by wrapping copper wire around a pot.

Raku

Raku originated in Japan in the 16th century, where raku vessels were and still are used in the traditional tea ceremony. It is a low-fire technique, where bisqued work is quickly heated to red hot temperature and then taken out of the kiln and reduced in wood shavings, newspaper or a similar combustible material. Raku ware is decorated with low-fire glazes, which usually contain a lot of frit. The clays used for this firing technique contain a high percentage of grog, so the work will be able to withstand the high temperature fluctuations, although this doesn't mean that other clays can't be used.

Raku ware may be sculptural, like some of the work of William K. Turner, handbuilt, or wheel-thrown, like the works of Jack & Cindy Philips.

Raku, with its battle with the elements of fire and smoke is an exciting technique, one that is suited to communal firings, as many dedicated workshops can testify. While it is an age-old tradition from Japan, it has found many devout followers in western ceramic communities.

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