Making Pitfired Pots

  • My wheel thrown vessels are fired in a primitive manner. At the leather hard stage, they are incised with various tools. When thoroughly dry, they are painted with several coats of terra sigillata, special slips which are made from clays that I have dug in Maui, Hawaii; The Bay of Fundy, Canada; Kiziloren, Turkey; Middleburg, Virginia; and Rhinebeck, New York. The polished surface is the result of burnishing with a smooth stone. To increase durability, the pieces are fired to a low temperature in an electric kiln, then smoked in sawdust.

  • The pitfire kiln is a rectangular box make of hard brick about 2 x 3 x 2 feet. A few pieces of work are placed in this kiln and packed with sawdust from various exotic hardwoods. The sawdust is lit and left to smolder for at least two days. The type of sawdust, atmospheric conditions, and amount and size of ware add to the variations in the final results. The subtle color changes take place as the carbon is absorbed by the porous clay body.

  • After years of carving and etching only geometric designs on my ceramics, my mind and hand revolted. The result was a continuing series of landscape and geologic carvings based on rocks, road cuts, mountains, and underwater vegetation. The work that I did after my sabbatical was called the Alien Series and the newest pieces were from the New Leaf Series.

Terra Sigillata

 

Terra sigillata means "sealed earth". It is made by decanting clay with sodium silicate so that it settles into layers; then one takes the clear liquid and the first layer of colored clay, discarding the rest.

All of the terra sigillata that I used were made from clays found on my travels. Wherever I went, whether I was looking for clay or not, I'd find it. The colors and places varied from a yellow in Rhinecliff, New York (found while excavating to build my kiln shed) to an amazing lilac purple on a volcanic island. My favorite was a vibrant persimmon red that came from Turkey along the Silk Road. I called it Kiziloren because that was the closest village to the site. Other clays that I used came from Cape Cod, Massachusetts; Maui, Hawaii; Middleburg, Virginia and the original brown from the Bay of Fundy, Canada. Some people make terra sigillata by grinding commercial clays and colorants with a ball mill. I never had to do that because I let mother nature do all the work for me. 

'Terra sig' is applied to bone dry pieces and then burnished. Most people are familiar with the stunning Greek Attic pots as well as Blackware from Oaxaca, Mexico and the exquisite work from Santa Clara and San Ildefonso, New Mexico.

Burnishing was the earliest way of sealing the surface of pots before humans figured out how to melt glazes onto the clay. In 1975 I got to use old Indian burnishing stones while taking a workshop with Maria Martinez and her son and daughter-in-law. Until that time I had been using a silver spoon to burnish.

I loved the process of burnishing—seeing the surface change from matt to shiny just by rubbing with a stone. I hated glazing pots because the surface always looked and felt like icing to me. The burnished surface is more like a skin, having a warmth to it that glazes will never have. Over the years I left glazes behind, no longer doing Raku and just pit firing, until the salt kiln debacle (explanation to follow later). None of the pit-fired pieces in this collection hold water.