The topic formats and photos in subsequent months are designed to be an outline for further reading, thought and discussion. It is not meant to be an exhaustive discussion but hopefully will function as a starting point for basic understanding of the ceramic process and history of clay at the University of North Dakota-UND. The viewpoint will be from the perspective of the clay tradition at the University of North Dakota, North Dakota School of Mines-NDSM. The assumption in the topical discussion is that the reader has some background and knowledge of NDSM, the UND Ceramics Department and the Cable era. When possible, additional references and resources will be suggested. Donald Miller is the writer of these ceramic and historical vignettes.
What Goes Into Making a Ceramic Object?
The process of producing a clay form has many parts: forming, drying, bisque firing, glazing and glaze firing. Clay is broken down granite-rock. Ironically the making of a ceramic object is the process of making the soft pliable clay, hard again. Western North Dakota has numerous clay deposits that were laid down millions of years ago.
The three primary methods of making clay forms at UND have been mold making or casting, hand building, and wheel throwing. Each of these techniques will be discussed at subsequent times. Another method, jiggering, which is a production process for making multiples, uses soft clay slabs placed in a turning mold, that is scraped with a steel or composite template. To the best of my knowledge, jiggering was not used during the Cable era for making pottery.
Drying must be done slowly. As the water evaporates from the form, it shrinks in size. If the various parts of the form dry unevenly-side to side/top to bottom-the form is very likely to crack. As clay dries, it passes through a stage called leatherhard, which is when it no longer has any flexibility. Completely dried clay is called greenware.
3. Bisque Firing-Bisque
(sometime spelled busquit) firing removes both the physically and chemically combined water. It is the first of two "firings" in the kiln. The kiln is the "oven" which is used by potters to fire their ware. A typical bisque firing will reach 1700 F over a period of 20 to 48 hours. Once the piece is bisque fired it can not be reclaimed as soft, wet clay. The bisque firing hardens the form, making it much less fragile and easier to handle during the glazing process.
This is the process by which a coating of glass/glaze is applied to the surfaces of a ceramic form. A glaze is a very specific form of glass and the chemicals in a glaze are balanced to help melt at a given temperature. Each temperature range requires a different chemical balance. Water is added to the balanced chemical mixture to facilitate the glaze application process. There are four main methods of applying glaze: painting, pouring, dipping and spraying. The bisque fired form is durable but still porous and absorbs the water from the glaze as it is applied, leaving a coating of the chemical mixture on the surface. The proper thickness of the glaze coating is critical. If it is too thick the glaze will run off the form, and if it is too thin the desired surface quality of the glaze and underglaze designs may be lost.
5. Glaze Firing
During the glaze firing the combined dry glaze chemical mix, which coats the form, melts and fuses into a glaze and onto the surface of the form. During the glaze firing process, there are two types of environments or atmospheres possible inside the kiln, oxidation and reduction. It appears that the historic Ceramic Department used an oxidation atmosphere almost exclusively.
Your local library is likely to have a number of excellent general
reference books on the introduction to clay. Try them before you buy
one of these. Here are three excellent clay books.
The Craft and Art of Clay: A Complete Potter's Handbook, By Susan Peterson
Hands in Clay: An Introduction to Ceramics, By Charlotte F Speight
Ceramics: A Potter's Handbook, By Glenn C. Nelson
The two best reference books on NDSM are:
University of North Dakota Pottery: The Cable Years by Donald Miller, available through this web site.
UND Pottery: A History and Comparative Study by Ken Forester, available through your local bookseller.