Introduction to Clay

Introduction to Clay

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  Introduction to clay Chapter1
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  What is thedifference? What is the difference between mud and clay? Clay is broken down minerals from a volcano
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  Clay has theability to hold together while being shaped because of its PLASTIC qualities. Everything you do with clay interplays with moisture, plasticity, and heat.
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  Dates back towhen people learned to control fire during the stone age. One theory suggest that people would make clay sculptures to help tell a story or for religious ceremonies. Origins of Ceramics
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  Origins of clay Sometimesclay was used for practical purposes like containers to cook in, eat out of, or to store food. They shaped these containers by pinching, coiling, or pressing over round stones. They even pressed clay into woven baskets. They fired their pottery in cooking fires which left the clay fragile and porous because of the low temperature of the fire.
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  Early Techniques As timemarched on and populations grew a need for larger containers grew for storage. These early people used symbols to identify and mark their containers. Scholars believe that this is probably the beginning of writing. Early techniques were developed such as drying work, firing, glazing, purifying clay, ect..
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  Early Techniques Production: Over timepotters began to improve each step and achievement. Sometimes the improvements were so great that other countries tried to copy like the delicate blue and white glaze from China in the 14th century. Some potters failed in their attempt to copy this glaze but their attempts lead to new discoveries.
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  Early Techniques Preparation Dug upraw clay from the ground then... DECANTING: separated impurities by adding water to the clay and them pouring the liquid clay (SLIP) from one container to the other. This process causes the impurities to settle to the bottom. Levigation: The clay is prepared as a slip and allowed to flow slowly down a gentle sloping channel. Finer particles flow over a lip while the courser impurities stay behind the lip.
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  Early Techniques Forming clay: Varietyof methods such as pinching, coiling, slab building, molding. Early potters often combined pinching and coiling to create vessels. Jomon- cord like clay (Coil) used for decoration in early Japan. Large objects such as statues or large containers were built using slabs of clay.
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  Early Techniques Clay shrinksas it dries, if it shrinks too rapidly, it can crack.So keep your work covered! Too much water makes your clay crack! Mist work lightly. Different clay shrinks at different rates so you can not mix different clay bodies.
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  Early Techniques Decorating Incising- carvingor cutting the surface with a sharp tool. Impressing- uses objects to press into the clay like a stamp. Combing- marking the clay surface with uniform lines Burnishing- rubbing leather hard clay with a smooth surface.
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  Early Techniques Glaze a thincoat of glass you give your pot. four main glaze types were alkaline, ash, lead, and salt.
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  Early Techniques Firing first kilnswere open pits or cooking hearths Kiln- and enclosed structure like a furnace designed to withstand very high temperatures. Upward draft downdraft
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  Important Vocabulary Stages ofClay: Leather Hard- Unfired clay that is the consistency of leather or cheese. The clay is still WORKABLE. Bone Dry- The clay is dry but unfired and easily breaks. The clay is NOT workable. Bisque- Your clay has been fired once but is still porous. This is when we glaze. Maturity- The point at which the glaze or ware has become vitreous. Greenware- All unfired stages of clay
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  How to attachclay SLIP AND SCORE!!!!! Score- to rough up or create texture on both pieces of clay to be attached. Slip- liquid clay, its the glue.