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Glazing and Firing. Glaze the process of coating a piece with a thin layer the raw materials which, after being fired in a kiln, will form a hard, glass-like.

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Presentation on theme: "Glazing and Firing. Glaze the process of coating a piece with a thin layer the raw materials which, after being fired in a kiln, will form a hard, glass-like."— Presentation transcript:

1 Glazing and Firing

2 Glaze the process of coating a piece with a thin layer the raw materials which, after being fired in a kiln, will form a hard, glass-like coating. Serves both functional and decorative purposes

3 Glazing Glazes are made up of materials that fuse during the firing process and form a vitreous (glassy) layer that adheres to the ceramic surface. Made up of 3 components: Silica Flux Refractory Material

4 3 Components of Glazes Silica: the vitrifying element (converts to glass) Flux: makes the glaze fuse with the clay Refractory Material: hardens and stabilizes the glaze.

5 Glaze Colorants The color of a glaze is produced by adding a metallic oxide (ex. Cobalt, copper, iron, nickel etc.) Each produces a color that can be modified by the other glaze components, the firing and the atmosphere of the kiln.

6 Types of Glazes Classified according to: How shiny they are (gloss & matt) Maturing temperature (low, medium, high)

7 Our Glaze Chart 123 4 56789 Etc. AA2A3A4A5A6A7A8A9… BB1B3B4B5B6B7B8B9… CC1C2C4C5C6C7C8C9… DD1D2D3D5D6D7D8D9… EE1E2E3E4E6E7E8E9… FF1F2F3F4F5F7F8F9… GG1G2G3G4G5G6G8G9… HH1H2H3H4H5H6H7H9… II1I2I3I4I5I6I7I8… JJ1J2J3J4J5J6J7J8J9 Etc. ……………………… A Wheat B Hazelnut C Sandy Tan D Cola Green (not green) E Sage Matt F etc…

8 Wax Resist Required for every pot/project. Keeps the base of your ware clean of all glaze so it will not melt to the kiln shelf during firing. Must be applied prior to glazing to be effective! May be applied by finger or wax-resist brush. Apply up the side of your project at least 1/8 inch.

9 Applying Glaze Dipping: submerging the ware in a bucket of glaze. Pouring: Pouring the glaze over the wares. Brushing: Painting the glaze on, three layers thick, each coat applied in a different direction. Spraying: Using a booth and a special glazing spray gun

10 Underglaze Colorant applied to the surface of your bisque ware before applying glaze Decorative **Low fire-- fires to the same temperature as a bisque fire (cone 05)

11 Stains Great for bringing out detail in carvings Not meant to be used as a glaze or in large portions. **Fired at any temperature

12 Engobes Applied only to leatherhard ware. Often used with scraffito Painterly effects, blending possible

13 Low Fire Glazes **Fire to the same temperature as a bisque fire (cone 05) Still requires that pieces be bisque fired first Expensive For painting only (3 even coats, applied in different directions)

14 Firing Atmospheres Oxidation -Usually takes place in an electric kiln -Oxygen is present in the kiln atmosphere Reduction -More fuel than oxygen present in kiln environment -Causes flames to seek-out oxygen -Creates color effects that cannot be achieved in oxidation.

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16 Kilns and Firing Techniques Bonfire Pit Fire Wood Fire Raku Gas Electric

17 Bonfire Most ancient method of firing clay Primitive, low firing temperatures

18 Pit Firing Firing in an excavated pit More efficient than bonfire Wares go in unglazed Fire-painted, colored by combustibles and chemicals

19 Wood Firing Fuel source is wood Pots are often glazed beforehand Ash from burning wood melts into glaze

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32 Raku Firing Pieces are super heated in a small kiln, pulled out while glowing hot and placed in a reduction chamber with combustible materials (Western Raku vs Japanese Raku)

33 Gas Firing Most common kiln type used by ceramic artists Temperature easily controlled by the amount of gas and air allowed in the kiln Able to fire in oxidation and reduction

34 Electric Firing Easiest kiln to use. Electric current heats internal elements Often have automatic shut-off Highly computerized

35 Cone Temperature Chart ConeTemperature (°F) 0221115 021…1140 061830 05…1900 012061 12093 2…2106 5…2174 92316 10…2361 122400

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