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Clay modeling

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ppt of clay hand building terms

Clay modeling

  1. 1. Ceramics
  2. 2. Primary Clay Clay found at the original site where it was formed by decomposing rock Secondary Clay Clay that has been transported from its original site by water, air or ice and deposited in layers elsewhere
  3. 3. Earthenware Clay that hardens at a low temperature but remains porous (able to absorb moisture). Earthenware is a secondary clay. Porosity The capacity of a clay body to absorb moisture
  4. 4. Preparing Clay Before making anything with clay, whether by hand or on the pottery wheel, the clay must be wedged so that it can survive the firing process. Pottery will explode in the kiln if air bubbles or impurities are in the clay or if certain areas are drier than others. In order to remove any air bubbles and evenly distribute water throughout the clay, it must be repetitively kneaded.
  5. 5. Plasticity The quality of clay that allows it to be easily manipulated and still maintain its shape
  6. 6. Leather hard The condition of unfired clay when most of the moisture has evaporated leaving it still soft enough to be carved into or joined to other pieces. Clay should be leather hard when building with slabs of clay
  7. 7. Bone dry The condition of unfired clay when it is as dry as possible prior to firing
  8. 8. Wedging Mixing and de-airing clay by cutting it diagonally and slamming the pieces together.
  9. 9. Kneading Working clay on a surface with the palms of the hands in order to remove air from it and obtain a uniform consistency
  10. 10. Clay Building Techniques Coil building Slab building
  11. 11. Coil A rope-like roll of clay used in hand building
  12. 12. Slurry/Slip A creamy mixture of clay and water often used as a glue to bond two pieces of clay together Viscosity The property of a liquid to resist movement. (Water has a low viscosity while syrup has a high viscosity.) Slurry should have a viscosity similar to that of pudding to be used for gluing pieces of clay together.
  13. 13. Clay Modeling Tools Clockwise from bottom left: wood rib, sponge, ribbon tool, loop tool, needlepoint tool, wood modeling tool, wire clay cutter, steel rib
  14. 14. Rib A hand held tool made of hard material used for shaping ceramic pieces and compressing clay particles
  15. 15. Kiln A furnace, built of refractory (resistant to heat and melting) material, for firing ceramic ware
  16. 16. Firing The heating of clay or glaze to a specific temperature
  17. 17. Greenware Unfired clay pieces
  18. 18. Bisquit or Bisqueware Clay pieces which have been fired once and are unglazed
  19. 19. Kilns and Firing <ul><li>Kilns are used to fire pottery </li></ul><ul><li>Pottery is considered to be in the greenware stage until it is fired </li></ul><ul><li>After its first firing, it is bisqueware </li></ul><ul><li>Bisqueware can be covered with coats of glaze and fired again numerous times </li></ul>
  20. 20. Warping Distortion of a clay shape cause by uneven stresses during shaping, drying or firing
  21. 21. Cone Firing Pyrometric cones are devices that gauge heatwork (the combined effect of both time and temperature) when firing materials inside a kiln. Cones range from 022 (the coolest) to 42 (the hottest). Earthenware clay is fired around 1900 degrees Fahrenheit, or between cone 06 and cone 04.
  22. 22. Cone Small, pyramid-shaped forms of ceramic materials made to bend and melt at specific temperatures and gauge the temperature of the kiln
  23. 23. Pyrometric Cones Guide Cone: One cone number below your goal Fire Cone: The cone number you wish to achieve Guard Cone: One cone higher than your goal
  24. 24. Glaze Techniques Glazes can be applied with any technique imaginable. The most common applications are painting, dipping, or spraying.
  25. 25. Glaze A glass-like coating that is bonded to a surface through heat
  26. 26. Vitreous Glass-like; hard, dense, and non-absorbent
  27. 27. Glaze Firing <ul><li>A second kiln firing after the initial bisque firing in which glaze materials are heated sufficiently to melt and form a glass-like coating over ceramic pieces when cooled </li></ul>
  28. 29. Key Terms pottery that has been fired but not yet glazed ceramic ware made of porous clay fired at low heat pottery that has not been fired stage in the drying process of clay where all shrinkage has occurred clay that has been saturated with water to create a thick liquid process of cutting grooves into a piece of clay where another scored piece will be attached method of de-airing and dispersing moisture uniformly by hand in a piece of clay devices that gauge heatwork (the combined effect of both time and temperature) when firing materials inside a kiln Bisqueware Earthenware Greenware Leather hard Slurry Scoring Kneading Cone

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