Salt-glazed ceramics were first created in the Rhine Valley of Germany in the 1500s. Whether by accident or clear intent, salt was introduced into the kiln and the resulting ware was coated with a glossy, pebbly, glazed surface. This is what salt-glaze potters call the telltale "orange peel" effect. German immigrants who settled in the United States brought the technology to this country and used it to create utilitarian vessels for storing food and liquids.
Although much of what we know about ceramics came from Asian cultures, salt-glazed ceramics did not find their way to Japan until the mid-20th century, due mostly to the trials and errors of contemporary potters Shoji Hamada and Bernard Leach. The salt-glazed ceramics that I create reflect more on their work than on the American potters of the 19th century. Like Hamada and Leach, I love the unpredictable effects that salt vapors impart upon both smooth and textured clay surfaces. With this medium, the artist has less control over the finished product and the results can be very unpredictable, yet the end results, when the kiln gods are smiling, can be most spectacular.
The underlying reason for the unpredictability of salt-glazing lies in the firing process. Because salt-vapors are extremely caustic and will eat away at metal and non-refractory brick, a special kiln is needed for firing salt-glazed ware. The kiln that I use was constructed on site using a refractory material of concrete, clay, sawdust, vermiculite and aluminum hydrate. Over the course of many firings, the interior chamber of a salt kiln builds up a layer of residual salt glaze and chemical oxides that can affect each subsequent firing. Fresh salt, in the form of wet halite crystals, is introduced into the hot kiln in the final stages of firing, where it will immediately vaporize and cover the surfaces of everything in the kiln. Each ceramic piece needs to be placed on wads of coated clay to prevent it from fusing to the kiln shelves upon which it is placed. Salt-firing is a labor-intensive process and one that is full of variables. When to add the salt, how much salt to add, the placement of ware inside the kiln, the presence of coloring oxides within the clay body, the temperature to which the kiln is fired, how long the kiln is cooled --- all of these affect the final results and ultimate success or failure of a salt firing.
Because salt-glazed ceramics are fired to stoneware temperatures in the Cone 10 (2381 degrees Fahrenheit) range and have a non-toxic, salt-glazed surface, they are extremely durable and may be used for food and liquids. Decorative pieces may be displayed outdoors but should not be left out in freezing conditions. All salt-glazed piecesare dishwasher safe.