Notes: Introduction to Ceramics

Ceramics

I. Vocabulary

• Ceramics = A nonmetallic, inorganic material that is exposed to extreme heat. The most common ceramic material is clay, but glass, plaster, and cement are ceramic materials, too.

I. Vocabulary

Ceramics

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I. Vocabulary

• Pottery = Ware, such as vases, pots, bowls, or plates, shaped from moist clay and hardened by heat.

I. Vocabulary

Pottery

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I. Vocabulary

Clay

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I. Vocabulary

• Clay
• What is it? Clay is the most universal material on earth. About 75% of the earth’s surface is clay or will eventually become clay…

I. Vocabulary

…Clay is used to make more than just pottery. It can be found in many common items such as bricks, roof tiles, curling irons, spark plugs, and even...

I. Vocabulary

• Where does it come from? Clay comes from a rock called feldspar.

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I. Vocabulary

…It takes centuries of geological weathering (being rained on, smashed by glaciers, having plants decay on it, etc.) to turn this rock into dust.

#6 Geological weathering

#6 Geological weathering

I. Vocabulary

After lying around in the bottom of swamps and lakes, the dust picks up water and forms clay.

I. Vocabulary

• The chemistry of clay:

Al2O3 ● 2SiO2 ● 2H2O

I. Vocabulary

SiO2 = Silica

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I. Vocabulary

H2O = Water

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II. Properties of Clay

• Plastic = Plastic is defined as a material that can be molded. Clay is able to hold its form but is also able to be molded by hand. Water is necessary to make clay plastic.

#10 Plastic

II. Properties of Clay

• Porous = Porous means clay is full of small holes so that water can escape as the clay dries. This keeps the clay from cracking as is dries.

#11 Porous

II. Properties of Clay

• Able to Vitrify = Vitrification is the conversion of clay into a hard glasslike substance when it is fired at a high temperature.

III. Working with Clay

• Forming Greenware
• Hand building methods = pinch, coil, slab, and modeling. Clay can also be thrown on a pottery wheel.

III. Working with Clay

• Preparing clay
• Wedging= a large piece of clay is first cut into pieces with a cutting wire, then the pieces are rearranged and slammed together to make it easier for kneading.

#13 Wedging

III. Working with Clay

• Kneading = similar to kneading bread. The clay is rolled over on itself and pressed down several times. After kneading, cut the clay with a wire to check that there are no air pockets or lumps.

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Kneading
Pinch method
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Coil method
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Slab method
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Modeling

III. Working with Clay

• Score and slip = used to join two pieces of clay together. A fork or needle tool can be used to score (or rough up) the surface and then slip (watered down clay) is applied at the joint like glue.

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Score
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Slip

III. Working with Clay

• Leather hard = when the clay has dried enough to be tough (like leather) but still workable. Used when building large forms.

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Leather hard

III. Working with Clay

• Bone dry = when all of the water has evaporated from the clay and it can be fired. It can take several days for a piece to become bone dry.

III. Working with Clay

• Kiln = the equipment that heats up clay like a super-hot oven

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Inside a kiln

III. Working with Clay

• Firing and Glazing
• Bisque firing = the first firing. Our clay is bisque fired at Cone 04, which means the kiln shuts off when it reaches 1915 F. After being bisque fired the ceramic piece is called bisqueware.

III. Working with Clay

• Glazing = Glaze is applied only to bisqueware. There are many different types of glaze. They can be applied by dipping, spraying, or brushing on.

III. Working with Clay

• Glaze Firing = this is the second firing. Our glazes are all Cone 06, which means the kiln heats them to 1798 F. Once the piece has cooled it is finished!