Saggar-Firing:
  Blending the Controlled and the Capricious

by Dick Lehman

From the beginning of my involvement with clay, I have been drawn to pots in which two paradoxical qualities are present: 1) pots which are carefully crafted, disciplined and controlled, and 2) pots which are at the same time almost magically affected by the uncontrollable, unrepeatable and capricious qualities of the firing process.

It probably comes as no surprise that these affections let me early to raku firing. And here a brief story warrants retelling:

Several years ago I hosted a visiting Canadian potter to three days of raku firing at my studio. Having limited time we decided to fire on day two, in spite of some very stormy weather. By dashing out to the kiln between cloudbursts we mostly avoided getting soaked. However, at the moment of moving one of my larger pots from the kiln to the post-firing reduction container, a tornado touched down several miles away. Moments later a resulting gust of wind toppled the container, and my prized pot rolled down a dirt embankment into a large clump of wet grasses. Cursing my luck I retrieved the pot, re-covered it, and waited with dismal certainty for it to cool and confirm its almost-certain demise. But to my surprise I discovered a colorful photo-like image of the wet grasses on the side of the pot.

That serendipitous discovery led me to an intentional pursuit of fresh leaf images on raku pots. Over time I was able to coordinate imaging with almost photographic clarity over the otherwise unpredictable copper matt stains.

Eventually I was introduced to low-temperature salt-firing and contemporary saggar-firing. Eighteen months ago I decided to attempt to combine parts of three firing technologies: to link what I had learned from the organic imaging of raku firing with the two firing procedures mentioned above. The results, while slow in developing, have been tremendously exciting.

First, a little background: "saggar" is a term used for any structure which encloses a pot during firing: it could refer to a large lidded pot which houses a smaller pot. Even an enclosure of stacked bricks with a kiln-shelf-lid would qualify as a "saggar."

In times when kilns were fired only with "dirty-firing" wood or coal, saggars were sometimes used to protect the pot from the undesirable residue of the combustion process. With the advent of cleaner-burning fuels, the necessity for saggars diminished.

I usually use a stacked-brick enclosure in my car kiln as a saggar. On the kiln-shelf-bottom I lay down 5-10 cm of fine sawdust. Next I take bisqued pots and press them into the sawdust to create impressions. (To vary effects of the firing I press pots in right-side-up, upside-down, sideways, touching one another, and balanced on top of one another.)

Freshly picked leaves, flowers and grasses are laid into the impressions, and pots are placed on top of the organic material. Rock salt and metallic salts (I use mostly copper sulfate and cobalt sulfate) are sparingly sprinkled adjacent to, and on top of, the pots.* More sawdust and leaves sometimes follow. Often at least one-third of the pot remains uncovered.

Tight-fitting kiln shelves serve as a lid to the saggar. I use guide cones placed atop the saggar for firing. While the temperature inside the saggar is always lower than the guide cone, routine use of cones outside the saggar leads to relative consistency inside the saggar from firing to firing. I have always had pleasing results and repeatable leaf imaging at a wide firing range — from cone 08 to cone 10 — although I prefer the lower end of this range.

I have used natural gas-fired car kilns, propane-fired raku barrel-kilns, and top-loading electric kilns for saggar-firing — all with fine results. (If you use an electric kiln, be sure to have adequate ventilation in and around the kiln; saggar firings have no measurable effect on shortening the life of electric elements.)

Sometimes the effect of the firing and cooling will cause the surface layer of clay to craze (a process called "dunting"). To the extent that it reveals something about the process, I find dunting a tasteful decorative force. And it in no way compromises the structural integrity of the pot.

Within this process the potter who uses saggars creates a setting, an opportunity...an "atmosphere"...where the magic of the firing may do its work. The range of colors, tones, and color-shapes — the deep carbon blacks, the pastel hues, the varying specificity of the leaf-imaged areas — all are determined by the saggar stacking procedure, the materials used, the temperature of the firing, and the amount of oxygen available in the saggar. Each firing is different, but equally exciting.

This procedure allows controlled, carefully crafted pots to be subjected to a process which contains limited controls; a process which, in large part, invites the magic of variables and imprecision to have the final word.

This blend of paradoxical forces leads to, in my way of thinking, both the most enlivening pots, and the most passionate and productive lives. Enjoy!

Dick Lehman, along with 11 other producing artists and craftsmen, maintains his studio in a late-19th-century factory building (called "The Old Bag Factory") in Goshen, Indiana, USA. He recently hosted Australian potter Audry Yoder Heatwole for a 10-week studio exchange.

*As metallic salts are soluble and extremely toxic, careful safety controls must be in place to limit any exposure via respiration or touch. Responsible clean-up and waste disposal is incumbent upon all artists who use toxic materials.

This article has been reprinted from the 1990, Volume 29, Number 3 Issue of Pottery In Australia Magazine.

© Dick Lehman, 1990. All rights reserved.