Pottery and Ceramics
It's All About The Clay
Listed below are articles letting you know about all the different characteristics and kinds of clay and how the different chemicals effect the clay when they are added and the different temperatures that they are fired at. Also if you would like to try digging your own clay the info here will help you be successful.
Tools for Pottery
Tips & Techniques for Pottery and Ceramics
Clay Pottery Craft Projects
Clay Pottery Articles of Interest
Old Time Pottery History
Pottery and Ceramics
Featured Potters Gallery
Pottery and Ceramics Definitions
All About The Clay
All About Pottery Glazes
It was formed when feldspathic rocks disintegrated by the erosive forces of wind, rain, heat, cold, the movement of ice during the ice ages and organic acids acting on the clay particles as vegetation decayed.
Clay is made mostly of alumina, silica and water, along with smaller amounts of other materials.
The most important quality that distinguishes clay from other minerals and soil is plasticity.
Plasticity refers to the ability of the clay to take and hold the form that the potter gives it.
Clays that are easily molded without cracking are considered more plastic than those that will not bend easily.
Clay is plastic because its particles are flat and stick together like a pack of wet playing cards.
The particles slide and support each other when we manipulate the moist clay.
Clay in its moist state is often referred to as plastic.
Clay that is rigid, but not yet dry, is called leather-hard.
Completely dry clay is bone dry and clay objects which have dried are called greenware.
Objects which have been fired to a low temperature 1472˚ F to 1832˚ F are called bisqueware.
There are many different kinds of clays.
Some of the most commonly used are:
Kaolin |
white, relatively non-plastic, vitrifies at very high temperatures. |
Earthenware |
various colors, usually plastic, matures at low temperatures but remains porous. |
Stoneware |
various colors, usually plastic, vitrifies at medium to high temperatures. |
Ball Clay |
buff color, very plastic, vitrifies at high temperature. |
Fire Clay |
buff to gray colors, non-plastic, vitrifies at very high temperatures. |
Bentonite |
buff to white, extremely plastic, meaning unworkable alone. |
Because a particular kind of clay dug straight from the ground may not be plastic enough or may not be the color we want or may not mature at the temperature we want, we usually will combine different kinds of clays or add different materials to our clay.
These man made clays are called clay bodies.
The most commonly used clay bodies fall into one of the following categories:
Earthenware
-wide range of colors from white to dark brown, usually plastic, matures at low temperatures, but remains porous.Stoneware
-various colors, usually plastic, vitrifies at medium to high temperatures.Porcelain
-white, relatively non-plastic, vitrifies at high temperaturesRaku clay
-various colors, plastic, porous at a wide range of temperatures.Raku clay is formulated to withstand thermal shock, which means extreme, abrupt changes in temperature.
| Some people are like blisters...they don't show up until the work is done. |
