Clay Notes

Where does clay come from? Clay comes from the ground, usually near areas where there is water. –Topsoil is top layer of ground, clay found below topsoil –Clay found near lakes, rivers, and reservoirs –Can also be found in dry areas in powdered form –Clay is mined in Wisconsin

How does clay get from the ground to PHS? Clay is mined from the ground Raw materials are added to clay and mixed Clay is filtered to remove unwanted material Extra water is removed from clay Air is removed from clay Clay is formed into blocks and shipped to schools, businesses, and artists

Different types of clay Clay gets its color from elements and materials in the ground. Traditionally red, grey, and white. Earthenware – low fire clay, easy to work with, needs glaze to hold water Stoneware – medium fire clay, very hard and durable, holds water without glaze Porcelain – high fire clay, difficult to work with, very strong

Important Clay Terms Wedge – process of blending clay to remove air bubbles Plasticity – how flexible the clay is, depends on the moisture of the clay Porosity – how much water the clay can absorb Shrinkage – how much clay shrinks as it dries, is fired, and is glazed

Important Clay Terms Greenware – clay that has been shaped, but not fired in the kiln, very fragile Leather hard – clay is dry, but not all the way Bone dry – clay is all the way dry, nothing can be added at this point Bisque – clay has been fired once and is hardened, but not glazed or painted

Bisque pottery Greenware, before being fired in a kiln

Clay Processes Pinchpot – Pinching a ball of clay into a functional bowl Coil building – Rolling and stacking coils on top of each other to create a cup, bowl, vase, etc.

Pinch pot Coil building

Clay Processes Slab building – Rolling slabs of clay to usually create boxes or vases Throwing – Using a potters wheel to create perfectly circular cups, bowls, plates, etc.

Slab building Throwing on a wheel

Clay Processes Scratch and slip – Used to attach clay to clay. Placing small scratches on the surface of the clay and using slip (clay glue) to hold clay together.

Scratching clay Clay slip

Clay Decorating Glaze – Used to add color to finished clay pieces. Traditionally painted over bisque fired clay, then fired again to reveal colors and patterns Paint – Acrylic, latex, and watercolor can be added to the surface or bisque fired clay. (Room temperature glaze)

Glaze before kiln Glaze after kiln

Glossy and matte glaze

Clay Decorating Kiln – Clay oven that operates at extremely hot temperatures –Usually around 1400 – 2500 degrees F –Used to turn brittle, dry clay (greenware) into strong, durable clay –Used to alter dry, unattractive glaze into colorful, attractive glaze

Modern electric kiln Man made brick kiln

A. Fettling knife B. Sponges C. Ribbon or Loop tools D. Rib Tool: used to smooth out the surface of clay pots E. Banding wheels: used for hand building, coiling, and decorating Clay Tools A B C D E