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Welcome to. Ceramics. The Exciting World of Clay awaits you…. A few items to remember:. We share this room with Art classes who do not want their projects dirty! Keep your area clean! There are specific areas for EVERYTHING! Each of you will be a part of a rotating job schedule.
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Welcome to Ceramics
A few items to remember: • We share this room with Art classes who do not want their projects dirty! Keep your area clean! • There are specific areas for EVERYTHING! • Each of you will be a part of a rotating job schedule.
Keep your clay projects in your own space! • Make sure you put all of your projects on your designated shelf each day. • Do not touch anyone else’s shelf space! • Keep track of what is on your shelf space!
Ceramic materials are expensive! • A single box of clay costs around $20. • A single bottle of glaze costs between $10-$20 dollars. • We will use between 35-50 boxes of clay and 50-60 bottles of glaze this year! • Please respect ALL supplies and take care of your materials !
Ceramics Fee: • There is a $25/student fee for Ceramics. This is used to offset the cost of materials. • Money is due by Friday, Sept. 9th.
If you took Ceramics because you think you want to make this:
What is Clay? Clay is a residual of rock erosion. Crystalline rocks, consisting of all sorts of silicates, especially field spars, never completely erode. The remains of the erosion are often soft clays, consisting of very small grains of silicates.
Clay • About 75% of the earth’s surface is either clay or will be clay. • Over 100 million tons are mined in the United States each year.
Clay Mining Mining clay by excavator to mass produce clay tiles for roofing. Mining clay by hand in Africa to use in making pots.
History of Ceramics • Early man had to solve the problem of how to store food. To do this, they looked to what was available to them. The combination of clay and fire solved this problem.
History of Ceramics • When clay is wet, it is easily molded. When it dries, it will hold its shape. However, if it gets wet again, it will get soft again and lose its shape. So by itself it isn't very useful as a storage container. However, being subjected to fire changes all of that.
History of Ceramics • When clay is subjected to fire or high temperatures, chemical changes take place that makes the clay keep its shape even if it gets wet again. It is now useful for storing food because wet weather won't cause it to dissolve. With a good lid or stopper, it can keep out insects and rodents because they can't eat through the fired clay.
History of Ceramics • The impact of creating containers that could withstand the weather and keep out pests gave humans a huge advantage over other animals. • Pottery making is a technology that nearly all cultures mastered, which helped them survive the harsher seasons and periods of little food or game. Without this practical use of chemistry, humans may have gone extinct.
Today, clay is used to create a variety of functional and decorative items, both manufactured and hand-built.
Properties of Clay • How is clay different from dirt? • Plasticity • Porosity • Vitrification
Plasticity • The quality that allows clay to be formed and retain the form until dry. Clay has to have the ability to hold its form while at the same time be pliable enough to be moved by the potter’s hands.
Porosity • A clay, to be usable by the potter, must be porous enough to allow the water to escape evenly. Clay must dry without cracking. These pieces are unfired and porous
Vitrification • The process of becoming glasslike. It is necessary that the clay become hard at a reasonable temperature.
Three types of clay • Earthenware • Stoneware • Porcelain-type
Earthenware • Usually a red clay used to make flower pots, red brick, roofing tile, and similar products. Earthenware is a low-fire clay that is soft and not very strong. It is also porous when fired. Earthenware can be brown or buff-colored naturally. White earthenware clay needs to be manufactured.
Stoneware • Typically light grey or tan in color, stoneware is hard, strong, and non-porous when fired.
Porcelain-type • These clays are white or off white and hard when fired. Porcelain is a non-plastic clay body and difficult to handle. Porcelain is not a natural clay.
How hot do you think a kiln gets? How long does a firing cycle take? From start to completion, how long do you think it takes to make one project?
Bisque fire • A first fire in which the clay is left hard but porous. It is usually about 1800 degrees Fahrenheit.
Bisqueware • Pottery that has been bisque fired.
Bone dry • Unfired pottery that looks and feels completely dry. Pottery must be bone dry before it is fired. • You cannot attach additional pieces at this stage. Bone dry clay is fragile.
Batt • A slab of plaster or wood upon which pottery is formed or constructed.
Dry foot • To clean the glaze (before firing) from the bottom, or foot, of a pot to prevent it from sticking to the kiln shelf.
Fettling • Trimming away excess or unwanted clay using a fettling knife.
Firing cycle • The entire process of firing pottery. The steps are water smoking, dehydration, the quartz inversion, oxidation, vitrification, and cooling.
Foot • The bottom of a pot. foot
Glaze • A thin layer of glass that is melted onto a pot for decorative or utilitarian purposes.
Glaze fire • A second fire in which the quartz inversion takes place and the glazed ware is vitrified.
Greenware • Pottery that has not been fired. Greenware may be wet, leather hard, or bone dry.
Grog • Clay that has been fired and ground into a powder. It is mixed into a clay body to increase porosity, decrease plasticity and shrinkage, or add texture.
Kiln • A box in which the potter fires his/her pottery.
Leather hard • Clay that has dried enough to be damp, but is no longer plastic or malleable. Pottery is best trimmed and carved and handles applied when the clay is leather hard.
Pinch pot • Clay pot made by pinching or working the clay with fingers.
Score • To scratch the surface of the clay for the purpose of attaching clay pieces together.
Shards • Broken pieces of fired pottery.
Slip • A liquid clay body. Used in conjunction with scoring to attach clay pieces together.
Stacking • The procedure of loading pottery into a kiln for firing.
Stilt • A three-pronged star-shaped device used to hold bottom-glazed ware above the kiln shelf.
Wedging • The action of kneading clay into a homogeneous mixture, compressing out air bubbles, and generally preparing the clay for use.
