Clay Information
Vocabulary
Score & Slip
Wedging Pinch Slab Coil Glaze Kiln |
Leather Hard
Greenware Bisqueware Glazeware Plasticity Shrinkage Grog |
Clay Construction
Pinch Construction
The simplest and oldest form of clay construction is the PINCH technique. This technique involves wedging some clay, rolling it into a ball, and pinching the clay to create the form that you want. To create a bowl, or container, simply press your thumb into a ball of clay and work around the ball, pinching in a spiral to thin out the walls. The pinch technique lends itself to organic and curvilinear forms.
Slab Construction
SLAB construction involves rolling slabs of clay out with a rolling pin, and connecting the pieces together by scoring and slipping. Slab construction lends itself to mostly geometric forms, such as cylinders, cubes, and cones. This technique, while simple to build, is very fragile in the greenware stage.
Coil Construction
COIL construction is a more intricate and intensive technique. The process involves rolling out coils of clay that are stacked on top of each other. Each layer of coil must be scored and slipped to the layer below. If at anytime the coils are not scored & slipped the project can suffer from separations, or breakage in the unfinished area. Coil construction allows for more elegant forms than either slab or pinch construction. This technique was the precursor to throwing on the wheel. Vase forms are easily achievable with this technique.
Wedging
The most important part of the building process is WEDGING. Wedging is a process of throwing your clay on a flat surface repeatedly. This process performs two things. First, it helps to spread moisture and water through the clay evenly, and second it forces any air bubbles out of the clay. If you didn’t perform this step on every piece of clay you use, you run the chance of turning the project in to a smoldering pile of clay dust.
Scoring & Slipping
The second most important process in constructing your clay project is SCORING & SLIPPING. Scoring & Slipping is a process that must be used to join two pieces of clay together that have not been wedged together. This process acts like a glue that insures that when you piece is fired it does not fall apart after it is out of the kiln.
Glaze
A silica based material with different chemicals mixed in that is fired to a temperature that melts it. Once the glaze has melted it leaves a thin layer of colored glass coating the surface of the clay.
Clay Bodies
Our Clay BodiesWe will be using 2 different clay bodies in this program: Laguna WC-609 #65 and Laguna WC-603 #45. Both bodies are bisque fired to cone 06 (1830° F) and can survive a glaze range of cone 6 to 10 (2232° to 2381°).
Plasticity
The ability of the clay to be manipulated and still maintain shape without cracking or sagging.
Shrinkage
The amount the clay shrinks when fired.
Grog
Hard fired clay that has been ground up and added to new clay. Grog reduces the shrinkage rate of the clay and makes it better for sculptural applications.
Stages of Clay
After you have gone through the building process, your clay must be set out to air dry. At this stage your clay is ready to go through the firing process. There are two stages to the firing process that we are going to work with: GREENWARE and BISQUEWARE. For the clay to be permanent it must complete only the first stage of the firing process.
Leather Hard
Clay that is not completely dry but is still able to be carved and shaped.
Greenware
Clay that has been air-dried but not fired. The clay will dissolve in water and is extremely fragile.
Bisqueware
Clay that has been fired once and is ready for glazing. The clay will not dissolve in water and is not fragile, but it is still breakable. The clay will not hold water.
Glazeware
Clay that has been fired a second (and final) time with glaze applied. The clay is able to hold liquids at this point.
The simplest and oldest form of clay construction is the PINCH technique. This technique involves wedging some clay, rolling it into a ball, and pinching the clay to create the form that you want. To create a bowl, or container, simply press your thumb into a ball of clay and work around the ball, pinching in a spiral to thin out the walls. The pinch technique lends itself to organic and curvilinear forms.
Slab Construction
SLAB construction involves rolling slabs of clay out with a rolling pin, and connecting the pieces together by scoring and slipping. Slab construction lends itself to mostly geometric forms, such as cylinders, cubes, and cones. This technique, while simple to build, is very fragile in the greenware stage.
Coil Construction
COIL construction is a more intricate and intensive technique. The process involves rolling out coils of clay that are stacked on top of each other. Each layer of coil must be scored and slipped to the layer below. If at anytime the coils are not scored & slipped the project can suffer from separations, or breakage in the unfinished area. Coil construction allows for more elegant forms than either slab or pinch construction. This technique was the precursor to throwing on the wheel. Vase forms are easily achievable with this technique.
Wedging
The most important part of the building process is WEDGING. Wedging is a process of throwing your clay on a flat surface repeatedly. This process performs two things. First, it helps to spread moisture and water through the clay evenly, and second it forces any air bubbles out of the clay. If you didn’t perform this step on every piece of clay you use, you run the chance of turning the project in to a smoldering pile of clay dust.
Scoring & Slipping
The second most important process in constructing your clay project is SCORING & SLIPPING. Scoring & Slipping is a process that must be used to join two pieces of clay together that have not been wedged together. This process acts like a glue that insures that when you piece is fired it does not fall apart after it is out of the kiln.
Glaze
A silica based material with different chemicals mixed in that is fired to a temperature that melts it. Once the glaze has melted it leaves a thin layer of colored glass coating the surface of the clay.
Clay Bodies
Our Clay BodiesWe will be using 2 different clay bodies in this program: Laguna WC-609 #65 and Laguna WC-603 #45. Both bodies are bisque fired to cone 06 (1830° F) and can survive a glaze range of cone 6 to 10 (2232° to 2381°).
Plasticity
The ability of the clay to be manipulated and still maintain shape without cracking or sagging.
Shrinkage
The amount the clay shrinks when fired.
Grog
Hard fired clay that has been ground up and added to new clay. Grog reduces the shrinkage rate of the clay and makes it better for sculptural applications.
Stages of Clay
After you have gone through the building process, your clay must be set out to air dry. At this stage your clay is ready to go through the firing process. There are two stages to the firing process that we are going to work with: GREENWARE and BISQUEWARE. For the clay to be permanent it must complete only the first stage of the firing process.
Leather Hard
Clay that is not completely dry but is still able to be carved and shaped.
Greenware
Clay that has been air-dried but not fired. The clay will dissolve in water and is extremely fragile.
Bisqueware
Clay that has been fired once and is ready for glazing. The clay will not dissolve in water and is not fragile, but it is still breakable. The clay will not hold water.
Glazeware
Clay that has been fired a second (and final) time with glaze applied. The clay is able to hold liquids at this point.
Firing Process
Kiln
The kiln is what makes the clay process work. The kiln is nothing more than a large oven, however it can reach temperature up to 2700°. The kiln dries out the clay completely, compressing the clay and making it permanent. It consists of a fireproof brick liner with either gas or electric elements to produce the heat. The following chart lists the cones and their corresponding temperature:
The kiln is what makes the clay process work. The kiln is nothing more than a large oven, however it can reach temperature up to 2700°. The kiln dries out the clay completely, compressing the clay and making it permanent. It consists of a fireproof brick liner with either gas or electric elements to produce the heat. The following chart lists the cones and their corresponding temperature: