POT MAKING The art of pottery

What is Clay? Clay is a mix of naturally occurring materials made up primarily of fine-grained minerals. Think of very finely ground up rock. The fine partials of rock are suspended in water. Different colors occur in clay because of impurities in the clay. Red clay is the results of Iron Oxide in the clay, while white clays get their color from Talc in the clay body.

The Stages of Clay The stages of clay refer to the different amounts of water mixed with the minerals that make up the clay. More water makes the the clay softer to the touch, less water makes the clay harder to the touch. Slip Clay Leather Hard Clay Plastic Clay Bone Dry Clay

Stage 1 : Slip Clay Slip clay is clay that has 25% clay to 75% water. Slip clay is used for a couple of different things. The first is as a glue when connecting two pieces of plastic or leather hard clay together. The second is as a decoration, when different colored slips are Glue painted on a pot it will leave a chalky painted design. The final use of slip clay is as a way to castceramic items in a mold. This is usually done in production work, like the plates and mugs that we see where the same form is used over and over again. Casting Painting Designs

Stage 2 : Plastic Clay Plastic clay is used when you are hand-building with clay. Pinch pots,coil pots, and wheel throwing are all done at this stage. Plastic clay is a mix of 50% clay to 50% water. It is easy to mold by hand, and can be connected together by scoring and slipping. You can tell a piece of plastic clay by Impressed texture squeezing it, if it doesn’t crack, and is soft between your fingers it is considered plastic. Plastic clay is the best time to make unique forms in the clay. The plastic stage of clay is also a great time to work in new textures. By pressing items into the clay new surfaces will result, because the clay is receptive to any texture! Creating Forms Wheel Throwing

Stage 3 : Leather Hard Clay Leather hard clay has 75% clay to 25% water in it. Leather hard clay can be connected together by scoring and slipping, but you do need to score aggressively to get the pieces to stay together. Leather hard clay is hard and cold to the touch, if Slab Box Forms you have a slab of clay and lift it up, it will not sag down. In this stage, the clay will crack if you try to bend it. Leather hard clay is a great stage to do carving or subtractive sculpture techniques because it Connecting slabs by scoring and gluing with slip clay retains the carved lines well. Hand Carving Leather Hard Clay Slabs

Stage 4 : Bone Dry Clay Bone dry clay is the final stage before the clay is fired. Bone-dry clay has 100% clay to 0% water. In this stage you cannot do any additive method, but you can do some limited subtractive work. Bone-dry clay will crack and break if pushed too hard, and is very fragile to the touch. When clay reaches this stage, you are usually ready to fire the work, We call this finished “Greenware”. Bone Dry Cups If you are not satisfied with your work, you can reclaim the clay by letting the clay soak it in some water. By letting it sit for a few days the clay will become slip clay and start the process all over again. Reclaiming Clay in a bucket of water Greenware loaded in a Kiln

Firing and Glazing the Clay Clay must be fired in a Kiln to make it permanent. The kiln heats the clay up to 2000 degrees to fusethe minerals in the clay together. When clay comes out of the kiln after it’s first firing, it is called “Bisqueware”. Bisqueware will not melt into slip if placed in water, and is ready to glaze. A view inside a hot kiln Glaze is the shiny, coating we see on most pieces of pottery. Glaze is made mostly of two components: Silicaa finely ground and pure sand, that gives the glaze a shiny surface Minerals thatgive the glazes their colors and textures. Glazed Pots

Some new sculpture terms Additive Sculpture Method: When two or more pieces of clay are pressed together to create a new form. Pieces that are done with the additive method should be scored and slipped to make them stick together. If a piece of clay is not scored and slipped it will most likely fall off in the firing. Subtractive Sculpture Method: When the clay is carved or pressed into it is considered a subtractive sculpture method. If the clay is carved or when clay is removed from the surface we call it a subtractive sculpture method. An Additive Sculpture A Subtractive Pot Often, a work of ceramic art will have both additive and subtractive methods used at the same time Both Additive & Subtractive Vase