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CLAY DEFINITIONS

1. CLAY:   Mud; moist, sticky dirt. In ceramics, clay is fine-grained, firm earthy material that is plastic when wet, brittle when dry, and very hard when heated.
   
2. The most common types of ceramic clays are:            earthenware            stoneware            porcelain
   
3. EARTHENWARE:   Earthenware is a low-fire clay that is porous and not waterproof.
   
4. WEDGING: A technique to make clay plastic and remove air pockets. The clay is thoroughly kneaded and cut before use in modeling or pottery.
   
5. DRYING STAGES:
   1. PLASTIC: Clay is plastic when it can be easily manipulated - modeled, molded or pressed into a desired shape; malleable.
   2. LEATHER HARD:  In ceramics, leather hard is a state in which clay has lost moisture to evaporation, but has not yet completely hardened. The clay is damp enough to be joined to other pieces with scoring and slip.
   3. BONE DRY:  In ceramics, greenware which is thoroughly room dried is said to be bone dry.
      
6. CLAY BUILDING TECHNIQUES:
   1. PINCH POT - Pinching is a fundamental pottery technique. Making a pinch-pot is pressing the thumb into a ball of clay, and drawing the clay out into a pot by repeatedly squeezing the clay between the thumb and fingers.
   2. COIL - Long, snakelike ropes of clay that are used in making pottery. The coil method of making pottery involves building the walls of a pot with a series of coils into the required shape.
   3. SLAB BUILT - Clay slabs are cut to shape and joined together using scoring and wet clay called slip. Scoring and applying slip to such roughened surfaces creates a bond that holds the pieces together.
   4. RELIEF -  A type of sculpture in which form projects from a background. There are three types of relief: high, low, and sunken.
      1. In high relief, the forms stand far out from the background.
      2. In low relief (best known as bas-relief), they are shallow.
      3. In sunken relief, the backgrounds are cut back and the points in highest relief are level with the original surface of the material being carved.
7. GREENWARE:   Greenware generally refers to unfired pottery.
   
8. BISQUE: Bisque clay has been fired once but has not been glazed. Also called biscuit.
   
9. KILN: A kiln is a special oven or furnace that can reach very high temperatures and is used to bake, or fire clay.
   
10. FIRING:   Firing is the process of baking and hardening pottery. The high temperature fuses the clay particles together, hardening the clay. Temperatures in kilns can reach 2500 degrees.
    
11. SCORING:  Making scratches in pieces of clay to be joined together is called scoring.
    
12. CLAY SLIP:  Slip is made by mixing clay with water.  Slip is a fine, liquid form of clay used with scoring to cement together parts that have been formed separately.
    
13. GLAZE:  Glaze is a thin coating of minerals which produces a glassy transparent or colored coating on bisque ware. Glaze is fixed by firing the bisque ware in a kiln. Two kinds of glaze are:
    1.  Underglaze is liquid clay mixed with minerals to produce a color that is painted on the piece.
    2.  Overglaze is a glassy colored coating or a glassy, transparent coating that is painted on top of underglaze.