Salt glazed stoneware
Salt glazed stoneware first evolved in medieval Europe as potters sought out new ways of making their pottery vitreous. I fire my salt glazed stoneware in a custom designed firebrick kiln. It takes a full day of focused work to load the kiln. The placement of each pot in the kiln must be considered, as it will have a direct influence on the resulting effects. After I load the kiln, I pilot it for at least one day to completely dry the pottery and the kiln. Any moisture could cause cracking and explosions during the firing. Then over about twenty hours, I slowly increase the kiln temperature to 2400°F.
At peak temperature, I gradually introduce 40 pounds of rock salt through ports in the kiln wall. The intense heat vaporizes the salt and allows sodium vapors to react with the silica in the clay and glazes. This interaction forms a salt glaze and creates a glassy textured orange peel surface. I maintain the peak temperature for several hours. Once the firing is complete, the kiln must cool for three days before I disassemble the kiln’s brick door and get my first look at the newly fired pieces.
In salt glazed stoneware, the clay and glaze surfaces melt together more completely than in any other type of pottery, giving the surface aesthetic a cohesive quality. It is a beautiful as well as durable choice for everyday functional use.
The raku firing process originated in Japan with the evolution of Zen Buddhism and the Japanese tea ceremony. A raku kiln is small and usually fires only a few pots at a time. Over a few hours I heat the kiln to 1800°F, when the pots become radiant orange and the glazes molten. At that moment, I remove the pots from the kiln using tongs or insulated mitts.
I have less than a minute to actively influence the surface of the molten glaze. I place the hot pots into a pit or barrel lined with newspaper, which bursts into flames. This produces a thick black smoke that is absorbed into the clay, creating gray and black patterns on the surface of the pots. I seal the barrel, which reduces the oxygen inside and creates a variety of beautiful fluctuations of color in the glaze. After the pots have cooled, I scour away the smoke and ash to reveal vibrant colors and crazing in the glaze surface.
Raku pottery is porous, and has an earthy, soft, organic visual quality.
Earthenware pottery dates back thousands of years. A wide range of glaze materials can be used at earthenware temperature, making this process well-suited for expressing a wide range of color. I have developed my own glazes for earthenware, and I also apply a variety of oxides and stains that tint the clay color and create a broad palate of matte surfaces and textures.
I have developed a unique earthenware firing process. I use my salt glazed stoneware kiln, but I heat it to only 2000°F and do not add salt. However, during the firing, small amounts of residual salt glaze vaporize off the inner walls of the kiln and coat the pots. This causes the raw clay to take on a beautiful blushed, fire-stroked patina, and causes the glazed and tinted surfaces to soften into a subtle and interesting color palate.
Earthenware pottery is lightweight and has a soft, warm appeal.