Test Flashcards
What is clay?
Hydrous silicates of aluminum.
What is the chemical makeup of clay?
Al2O3 + 2SiO2 + 2H2O
Where does clay come from?
Weathered product of igneous rocks. On or below earths surface.
2 major types of clay?
Primary (residual clay: can be mined from the parent rock) and Secondary (sedimentary: clays that have been deposited in their present location by water, ice, and other weathering).
3 major qualities of clay?
Plasticity: must be easily shaped and hold shape well.
Porosity: must be open in structure to allow the water of plasticity to escape readily on drying.
Vitrification: must become dense, hard, strong, at a temperature suited to the production requirements.
Plastic
Very moist, moldable.
Leather hard
Moves but still holds shape, lost a lot of moisture but still not totally dry, carving done at this stage.
Green ware
Bone dry, no physical H2O, unfired.
Bisque
Unglazed, fired once to remove all moisture from the clay body.
Glazed
Glaze is powdery/dry before second firing.
Glaze fired
Glaze materials melt and form a vitreous coating on the clay surface.
Pinch
Hand building technique where clay is “pinched” by hands
Coil
Clay rolled into coils for building.
Slab
A thin slice/plate of clay. Made by using a roller.
Scoring and slipping
Scratching clay surfaces then adding slip (water and clay). Done to attach two pieces of clay to assure they don’t come apart.
What is decorative slip made of?
Clay and a colorant.
How is decorative clay colored?
With oxide or colorant.
What is joining slip made of?
Water and clay from the clay body that is being used.
Mishima
A design is carved into the clay body, slip is painted on the surface of the clay, then the outer layer is scratched off, leaving an indented colored design.
Scrafitto
Slip is applied to the surface the clay body, then the slip is carved away to make a design.
Slip trailing
A bottle with a smaller opening is used to draw a design.
Painting
Slip is painted on with a brush
Stenciling
A stencil or paper is laid on the clay body, the slip is put over that then the stencil is removed.
What is a glaze?
A layer or coating of a vitreous substance, which has been fire to fuse to a ceramic object to color, decorate, strengthen, or waterproof it.